Prepared for: Michael Coleman, AICP · 2019. 8. 26. · 1331 Garden Highway, Suite 300 Sacramento, CA 95833 Ph: 916.779.7300 F: 916.770.7371. Final Rinconada Water Treatment Plant

1331 Garden Highway, Suite 300 ● Sacramento, CA 95833 ● Ph: 916.779.7300 ● F: 916.770.7371

Final Rinconada Water Treatment Plant Upgrades Oak Woodland Mitigation Plan

Los Gatos, Santa Clara County, California

Project # 3700-12

Prepared for:

Michael Coleman, AICP Santa Clara Valley Water District

5750 Almaden Expressway San Jose, CA 95118

Prepared by:

H. T. Harvey & Associates

May 2016

Final Rinconada Water Treatment Plant Upgrades Oak Woodland Mitigation Plan i H. T. Harvey & Associates

May 2016

Table of Contents

Section 1. Project Requiring Mitigation .................................................................................................................... 1 1.1 Project Summary ..................................................................................................................................................... 1 1.2 Plan Purpose ............................................................................................................................................................ 1 1.3 Location and Site Description ............................................................................................................................... 1 1.4 Project Impacts ........................................................................................................................................................ 3 1.5 Types, Functions, and Values of Impact Areas .................................................................................................. 4 1.6 Local Plans and Regulations Governing Tree and Oak Woodland Impacts and Mitigation ...................... 6

1.6.1 Santa Clara Valley Habitat Plan ..................................................................................................................... 6 1.6.2 Santa Clara County Planning Office Guide to Evaluating Oak Woodlands Impacts .......................... 6 1.6.3 Town of Los Gatos Tree Protection Ordinance ........................................................................................ 7

Section 2. Revegetation Goal and Approach ........................................................................................................... 8 2.1 Introduction ............................................................................................................................................................. 8 2.2 Habitat Goals ........................................................................................................................................................... 8 2.3 Impact Avoidance and Minimization Measures ................................................................................................. 8

Section 3. Mitigation Design ..................................................................................................................................... 10 3.1 Habitat Revegetation and Mitigation Strategies ................................................................................................ 10

3.1.1 Oak Woodland Revegetation ...................................................................................................................... 10 3.1.2 Payment of Fees to Town of Los Gatos Forestry Fund ......................................................................... 10 3.1.3 Planting of Large Container Trees on Site ................................................................................................ 10

3.2 Tree Replacement Ratios and Mitigation........................................................................................................... 11 3.2.1 Native Tree Replacement Ratios and Mitigation ..................................................................................... 11 3.2.2 Nonnative Tree Replacement Ratios and Mitigation .............................................................................. 12 3.2.3 Tree Mitigation Summary ............................................................................................................................ 14

Section 4. Proposed Revegetation Site .................................................................................................................... 15 4.1 Location of Revegetation ..................................................................................................................................... 15 4.2 Revegetation Site Ownership Status ................................................................................................................... 15 4.3 Existing Functions and Values of Proposed Oak Woodland Revegetation Site ........................................ 15

4.3.1 Soils .................................................................................................................................................................. 15 4.3.2 Topography and Hydrology ........................................................................................................................ 17 4.3.3 Vegetation ....................................................................................................................................................... 17 4.3.4 Wildlife ............................................................................................................................................................ 17

4.4 Timing of Habitat Maturation ............................................................................................................................. 17

Section 5. Implementation Plan ............................................................................................................................... 18 5.1 Implementation Success ....................................................................................................................................... 18 5.2 Responsible Parties................................................................................................................................................ 18 5.3 Revegetation Site Construction Schedule .......................................................................................................... 19 5.4 Soil Amendments .................................................................................................................................................. 20 5.5 Planting Plan .......................................................................................................................................................... 20

5.5.1 Target Vegetation .......................................................................................................................................... 21 5.5.2 Seed Procurement ......................................................................................................................................... 21

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5.5.3 Mycorrhizal Inoculation ............................................................................................................................... 22 5.5.4 Seed Installation ............................................................................................................................................. 22 5.5.5 Plant Protection ............................................................................................................................................. 22 5.5.6 Mulch ............................................................................................................................................................... 23 5.5.7 Irrigation ......................................................................................................................................................... 23 5.5.8 Natural Recruitment ..................................................................................................................................... 24 5.5.9 Coarse Woody Debris Installation ............................................................................................................. 24 5.5.10 Schedule ........................................................................................................................................................ 24

Section 6. Maintenance Plan ..................................................................................................................................... 25 6.1 Dead Plant Replacement ...................................................................................................................................... 25 6.2 Irrigation ................................................................................................................................................................. 25 6.3 Weed Control ......................................................................................................................................................... 26 6.4 Plant Protection ..................................................................................................................................................... 26 6.5 Pruning .................................................................................................................................................................... 27 6.6 Natural Recruitment .............................................................................................................................................. 27 6.7 Schedule .................................................................................................................................................................. 27

Section 7. Monitoring Plan ....................................................................................................................................... 28 7.1 Introduction ........................................................................................................................................................... 28 7.2 Implementation Monitoring ................................................................................................................................ 28 7.3 As-built Plans ......................................................................................................................................................... 28 7.4 Performance and Final Success Criteria............................................................................................................. 28

7.4.1 Tree Survival .................................................................................................................................................. 29 7.4.2 Site Maintenance ............................................................................................................................................ 29

7.5 Monitoring Methods ............................................................................................................................................. 29 7.5.1 Tree Survival .................................................................................................................................................. 30 7.5.2 Health and Vigor ........................................................................................................................................... 30 7.5.3 Photodocumentation .................................................................................................................................... 30

7.6 Monitoring Schedule ............................................................................................................................................. 30 7.7 Adaptive Management .......................................................................................................................................... 31 7.8 Reporting ................................................................................................................................................................ 31 7.9 Completion of Mitigation ..................................................................................................................................... 32 7.10 Contingencies and Remedial Actions ............................................................................................................... 32 7.11 Statement of Financial Commitment ............................................................................................................... 32

Section 8. References ................................................................................................................................................. 33

Figures

Figure 1. Site Vicinity Map ............................................................................................................................................ 2 Figure 2. Tree Impact Areas ......................................................................................................................................... 5 Figure 3. Mitigation Site Overview ............................................................................................................................ 16

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Tables

Table 1. Native Tree Impacts ...................................................................................................................................... 3 Table 2. Nonnative Tree Impacts ............................................................................................................................... 4 Table 3. Summary of Tree Replacement Ratios for Native Tree Impacts ......................................................... 11 Table 4. Native Tree Impacts and Mitigation ......................................................................................................... 12 Table 5. Summary of Tree Replacement Ratios for In-Lieu Fee Mitigation ..................................................... 13 Table 6. Nonnative Tree Impacts and Mitigation .................................................................................................. 13 Table 7. Tree Mitigation Summary ........................................................................................................................... 14 Table 8. Revegetation Site Construction Events and Schedule ........................................................................... 19 Table 9. Target Species Composition for the Rinconada Oak Revegetation Site ............................................. 21 Table 10. Tree Health and Vigor Categories ............................................................................................................. 30 Table 11. Monitoring Schedule for the Rinconada Water Treatment Plant Revegetation Site ........................ 31

Appendices

Appendix A. Soils Information ......................................................................................................................... A-1

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Preparers

Daniel Stephens, B.S., Principal Restoration Ecologist Patrick Reynolds, M.S., Associate Restoration Ecologist Charles McClain, M.S., Restoration Ecologist Cissy Fu, Ph.D., GIS Specialist James Merk, M.A., Technical Editor

Final Rinconada Water Treatment Plant Upgrades Oak Woodland Mitigation Plan v H. T. Harvey & Associates

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Responsible Parties

The Santa Clara Valley Water District is the lead agency for the Rinconada Water Treatment Reliability Improvement Project, and Michael Coleman is the environmental planner assigned to the project and Linda Spahr and Nina Merrill are district biologists assigned to the project. Mike Munson is the RWTP Reliability Improvement Project Manager.

Michael Coleman, AICP Environmental Planner Santa Clara Valley Water District 5750 Almaden Expressway San Jose, CA 95118-3614 Telephone: 408.630.3096 [email protected]

H. T. Harvey & Associates prepared this oak woodland management plan. Patrick Reynolds is the primary contact person.

Patrick Reynolds, M.S. Associate Restoration Ecologist 1331 Garden Highway, Suite 310 Sacramento, CA 95833 Telephone: 916.779.7352 [email protected]

Final Rinconada Water Treatment Plant Upgrades Oak Woodland Mitigation Plan 1 H. T. Harvey & Associates

May 2016

Section 1. Project Requiring Mitigation

1.1 Project Summary

The Santa Clara Valley Water District (District) has construction underway of the Rinconada Water Treatment Plant (RWTP) Reliability Improvement Project (Project) (District Project No. 93294057-RWTP). The RWTP, which is the oldest of the District’s water treatment plants, was constructed in 1968, and numerous components of the plant are nearing the end of their useful lives. In addition, water quality and code requirements for potable water have become more stringent, requiring that the RWTP be upgraded to ensure the reliability of its operation and product water quality. The Project involves the systematic tear-down of much of the water treatment facility structures and the construction of a new, state-of-the-art water treatment facility on the RWTP property, while the plant continues to run at all times. Project construction will require the removal of trees from within the construction footprint.

1.2 Plan Purpose

This plan describes the detailed measures necessary to reduce impacts on trees on the Project site to a less-than-significant level, in accordance with the environmental impact report (EIR) prepared for the Project (Denise Duffy & Associates 2015) and considering the California Department of Fish and Wildlife (CDFW) comment letter on the draft EIR (CDFW 2014). This plan describes a hybrid approach that mitigates impacts on trees by establishing new oak woodland habitat on site using an ecological approach and through the payment of fees, in accordance with the Town of Los Gatos Tree Protection Ordinance. It includes descriptions of applicable policies and regulations governing tree and oak woodland impacts and mitigation and provides recommendations to minimize tree impacts and removal and to protect trees not targeted for removal. This plan includes a planting plan, implementation plan, and a maintenance plan for the revegetation site, and it identifies monitoring protocols and performance standards to ensure revegetation and enhancement success.

1.3 Location and Site Description

The site is located on approximately 39 acres at 400 More Avenue in the town of Los Gatos, California (Figure 1). It lies in a residential area bounded by More Avenue to the west, Granada Way to the north, the La Rinconada Country Club and Smith Creek to the east, residential uses to the southeast, and the Rinconada and San Jose Water Company enclosed reservoirs to the south (Assessor’s Parcel Numbers 407-34-002, 407-34-003, and 407-10-007). Elevations on the site range from approximately 280 feet in the east portion to about 435 feet at the main parking lot. Undeveloped portions of the property contain trees, landscaping, grassland, and oak woodland.

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Rinconada Water Treatment Plant Upgrades Oak Woodland Mitigation Plan (3700-12)

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1.4 Project Impacts

In 2005 and 2006, HortScience (arborist) evaluated all trees on the Project site (1,194 trees) (HortScience 2006). In 2015 and 2016, HortScience evaluated the trees again to reflect current tree conditions and tree impacts associated with the most recent construction plans (HortScience 2015, 2016). The 2015 tree survey indicates that Project construction will result in the removal of approximately 273 trees from the Project site (Figure 2) (HortScience 2016). Plans for fence replacement and the construction of a security pathway are still undergoing design development. As a result, impacts associated with these features are currently unknown. Thus, the 2016 arborist report did not address trees that will be affected by the fence and pathway (HortScience 2016). Impacts and mitigation associated with these project features will be addressed in the future.

Based on the 2016 arborist report and proposed mitigation, 232 of the 273 trees that will be removed will require mitigation. These included all native tree species with a 4-inch or greater diameter and all nonnative tree species with a 12-inch or greater diameter measured at a height of 54 inches (per the Town of Los Gatos Tree Protection Ordinance and agreement with the Town Arborist). The impacted trees for which mitigation is planned include 185 native trees (Table 1) and 47 nonnative trees (Table 2).

Table 1. Native Tree Impacts

Common Name Scientific Name Number of Trees Removed

Blue oak Quercus douglasii 15

Coast live oak Quercus agrifolia 101

Valley oak Quercus lobata 68

Willow Salix sp. 1

Total 185

Note: Impacts based on 2016 Arborists Report (HortScience 2016)


May 2016

Table 2. Nonnative Tree Impacts

Common Name Scientific Name Number of Trees Affected

Bushy yate Eucalyptus conferruminata 6

California pepper Schinus molle 4

Camphor Cinnamomum camphora 1

Coast redwood Sequoia sempervirens 1

Compact blue gum Eucalyptus globulus ‘Compacta’ 1

Corkscrew willow Salix matsudana 'Torulosa' 1

Monterey Pine Pinus radiata 2

Red flowering gum Corymbia ficifolia 2

Red iron bark Eucalyptus sideroxylon 26

River red gum Eucalyptus camaldulensis 3

Total 47

Note: Impacts based on 2016 Arborists Report (HortScience 2016)

1.5 Types, Functions, and Values of Impact Areas

The impact areas support a mix of mostly nonnative trees, including several species of eucalyptus (Eucalyptus sp.) and acacia (Acacia sp.), and several species of native trees and shrubs, including blue oak (Quercus douglasii), coast live oak (Quercus agrifolia), valley oak (Quercus lobata), California buckeye (Aesculus californica), and toyon (Heteromeles arbutifolia). Wildlife species expected to or known to occur in the woodland habitat include western gray squirrel (Sciurus griseus), acorn woodpecker (Melanerpes formicivorus), dark-eyed junco (Junco hyemalis), and red-tailed hawk (Buteo jamaicensis). Suitable nesting habitat for several protected migratory bird species is present in the woodland habitat. San Francisco dusky-footed woodrat (Neotoma fuscipes annectens) (SFDFW), a California species of special concern, is also known to occur in this habitat type. Several SFDFW nests were observed during Project site visits (Denise Duffy & Associates 2015). No special-status plant species were identified on the site, and none are expected to occur there (Denise Duffy & Associates 2015).

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LegendApproximate Rinconada Water TreatmentPlant BoundaryApproximate Tree Impact LocationsOak Woodland Revegetation Site


May 2016

1.6 Local Plans and Regulations Governing Tree and Oak Woodland Impacts and Mitigation

At the request of the District, H. T. Harvey & Associates (HTH) reviewed some local plans and regulations that guide the evaluation of impacts on native trees and oak woodland habitat and the development of oak woodland mitigation and avoidance and minimization measures to reduce impacts on trees. Because of the location of the Project site, as explained below, none of these plans and regulations apply to the Project. Nonetheless, some of them provide background information useful in developing an ecological approach toward mitigating the Project’s impacts on native oak species. The following text briefly describes the relevant plans and regulations.

1.6.1 Santa Clara Valley Habitat Plan

The Project site is not located within the boundaries of the Santa Clara Valley Habitat Plan (SCVHP) and is therefore not subject to its requirements. Nonetheless, as requested by the District, HTH evaluated Condition 14 of the SCVHP, which includes practices to avoid or minimize impacts on oak woodland during project planning and construction (ICF International 2012). (The SCVHP does not prescribe mitigation ratios for planting replacement oak trees.) Many of these recommendations were included in the arborist report and incorporated into the Project, including:

• Construct temporary project access points as close as possible to the work area to minimize tree removal.

• Align roads and pathways outside of tree root protection zones whenever possible.

• Grade road and pathways beneath or within 25 feet of the drip line of oak trees using hand-held equipment and use permeable surfacing to allow water infiltration.

• Minimize alteration of the natural grade through fill or other means within the root protection zone of oak trees.

• Minimize trenching for utility lines and other purposes within root protection zones.

• If pruning of oak trees is necessary, conduct pruning during the winter dormant period under the supervision of an arborist certified to International Society of Arboriculture or similar standards.

1.6.2 Santa Clara County Planning Office Guide to Evaluating Oak Woodlands Impacts

The Santa Clara County Planning Office Guide to Evaluating Oak Woodlands Impacts does not cover the Project because it is a project located within a City and therefore not subject to a county ordinance. Nonetheless, the guide identifies the following possible mitigation measures for impacts on oak woodlands:

• Plant replacement oak trees at a ratio of 2:1 or 3:1 based on the condition of the oak woodland habitat.

• Protect existing native oak trees on or off the project site from future development through a conservation easement at a ratio of 2:1 or 3:1 based on the condition of the oak woodland habitat.


May 2016

• Pay in-lieu fees to a natural resource agency or nonprofit organization for planting of oak trees to create oak woodland habitat in Santa Clara County.

This plan mitigates for impacts on native trees by planting native oaks and ornamental trees on site and by paying in-lieu fees to the Town of Los Gatos for the purchase of replacement oak trees at ratios that exceed those provided in the guide. Tree replacement ratios and mitigation are presented below in Section 3.2. Mitigation is per commitment made in District adopted final EIR and agreements between the District and Town of Los Gatos.

1.6.3 Town of Los Gatos Tree Protection Ordinance

The Town of Los Gatos Tree Protection Ordinance (Ordinance 2240) defines “protected” trees by criteria of trunk diameter and location. Protected trees include all trees located on developed industrial property having a 4-inch or greater diameter of any trunk at a height of 54 inches above the natural grade. The ordinance also specifies that protected trees removed on development projects must be replaced. The number of replacement trees is calculated by tree canopy size class. For example, trees with a canopy measuring 10 feet across or less are to be replaced with two 24-inch box-size trees, whereas trees with a canopy measuring more than 10 feet to 25 feet across are to be replaced with three 24-inch box-size trees.

This plan reflects the tree ordinance’s (2240 as updated in 2015) provision that protected trees removed be replaced at ratios prescribed in the ordinance with slight modifications based on the project-specific requirements imposed by the Town arborist. It also identifies measures to avoid and minimize impacts on trees. Section 3.2 in this document describes mitigation ratios that will be applied to the Project and as committed to by the Districts final EIR adopted in 2015.

The tree canopy replacement standards in the Town’s ordinance were slightly modified in 2015. For example, prior to 2015, trees with canopy measuring 4–9 feet across (instead of the new 10 feet across or less) were to be replaced with two 24-inch box-size trees, and trees with a canopy measuring 10–27 feet across (instead of the new 10–25 feet across) were to be replaced with three 24-inch box-size trees. This plan uses the tree canopy replacement standards that were in place prior to the 2015 amendment of the Town’s ordinance, as the tree canopy data were collected before the new ordinance was in effect.


May 2016

Section 2. Revegetation Goal and Approach

2.1 Introduction

The goal of this plan is to compensate for impacts on trees resulting from immediate Project construction. This plan takes a hybrid approach that mitigates impacts on trees by establishing new oak woodland habitat on site using an ecological approach toward revegetation, through payment of fees and planting of ornamental trees on site in accordance with the Town of Los Gatos Tree Protection Ordinance. The ecological approach toward revegetation will involve planting oak tree acorns in nonnative annual grassland habitat and protecting existing oak seedling and saplings from deer browse and competition from weeds. Soils within planting holes will be amended with organic compost and native mycorrhizal fungi to improve soil conditions and facilitate seedling establishment. Woodchip mulch will be spread around each planting to conserve soil moisture, regulate soil temperatures, and increase microbial activity (Zink and Allen 1998). Additionally, coarse woody debris piles will be installed to augment wildlife habitat and foraging opportunities in patches in and adjacent to the oak woodland site.

2.2 Habitat Goals

Implementing the proposed mitigation will result in the establishment of approximately 2.6 acres of high-quality oak woodland habitat through the planting of approximately 375 native trees, protection of 11 existing oak seedlings/saplings, and installation of coarse woody debris piles. The revegetation site will develop into mature oak woodland habitat and will be preserved in perpetuity.

2.3 Impact Avoidance and Minimization Measures

A number of impact avoidance and minimization measures have been incorporated into the Project. In addition, HortScience reviewed the latest design plans and provided additional protection recommendations. These measures largely follow what is described in Section 14 of the SCVHP (ICF International 2012) and in the past arborist reports (HortScience 2006, 2015, 2016). The goal of these measures is to decrease the number of trees that are removed or otherwise affected by grading and fill associated with the proposed construction area layout. The following measures have been incorporated into the Project:

• Preserve oak woodland communities that are adjacent to existing stands of protected oak woodlands to avoid habitat fragmentation and degradation of wildlife linkages.

• Maintain large and healthy trees whenever feasible.

• Establish buffer zones between preserved oak trees and development at a distance equal to or greater than the root protection zone.

• Construct temporary project access points as close as possible to the work area to minimize tree removal.


May 2016

• Align roads and pathways outside of tree root protection zones whenever possible.

• Grade road and pathways beneath or within 25 feet of the drip line of oak trees using hand-held equipment, and use permeable surfacing to allow water infiltration.

• Minimize alteration of the natural grade through fill or other means within the root protection zone of oak trees.

• Minimize trenching for utility lines and other purposes within root protection zones.

• If pruning of oak trees is necessary, conduct pruning during the winter dormant period under the supervision of an arborist certified to International Society of Arboriculture or similar standards.

Additional tree protection measures recommended by CDFW will be implemented during Project construction, including the use of stem wrap as needed to minimize damage to tree trunks, avoidance of stockpiling materials within the tree critical root zones, and the use of high-visibility fencing around the critical tree root zones to minimize root compaction by equipment.


May 2016

Section 3. Mitigation Design

3.1 Habitat Revegetation and Mitigation Strategies

Tree impacts will be mitigated by implementing a hybrid approach that mitigates impacts on trees by establishing new oak woodland habitat on site using an ecological approach, payment of in lieu fees to the Town of Los Gatos, and planting of ornamental trees on site in accordance with the Town of Los Gatos Tree Protection Ordinance 2240. These approaches are summarized below.

3.1.1 Oak Woodland Revegetation

Direct impacts on native trees will be mitigated through oak woodland revegetation and payment of fees to the Town of Los Gatos. Oak woodland plantings totaling 375 native oak trees will be installed on site and protected from deer and rodent browse and competition from weeds. An additional approximately 11 existing oak seedlings and saplings that have been identified in the proposed revegetation area will be protected from deer browse and weed competition. All planting propagules will originate from adjacent oak woodland, to the extent feasible, and be installed as acorns to reduce the risk of introducing sudden oak death and other diseases caused by plant pathogens such as Phytophthora spp. to the revegetation site via nursery container stock.

Habitat in the proposed revegetation site will be enhanced through the salvage and redistribution of coarse woody debris recovered from dead and living trees removed during Project construction or recovered from trees off site. The larger woody elements from these trees (branches and trunks 8 inches in diameter or larger) will be selectively placed in open areas of the oak woodland revegetation site to augment lower-tier canopy structure and to provide greater transitional cover for wildlife species in the largest gaps in the canopy. Other coarse woody debris can be piled to produce cover for small mammals, establish habitat for insects, and enhance cycling of nutrients in the soil.

3.1.2 Payment of Fees to Town of Los Gatos Forestry Fund

For trees not mitigated through oak woodland revegetation and planting of large container stock trees on site, in lieu fees will be paid to the Town Forestry Fund according to replacement ratios described below in Section 3.2.2. The fee per replacement tree is $250 per tree.

3.1.3 Planting of Large Container Trees on Site

In addition to oak woodland revegetation and payment for replacement trees, a total of 107 15-gallon, 24-inch box and 36-inch box trees will be planted on-site outside of the oak woodland mitigation area. These trees will be credited toward replacement trees described in Sections 3.1.2 and 3.2.2.


May 2016

3.2 Tree Replacement Ratios and Mitigation

Tree replacement ratios will be based on the size of the affected trees and will vary by mitigation approach. Native tree replacement ratios will be based on trunk diameter at breast height (dbh) for oak woodland revegetation mitigation and on tree canopy size for in-lieu fee mitigation. Nonnative tree replacement ratios will be based on tree canopy size for in-lieu fee mitigation.

3.2.1 Native Tree Replacement Ratios and Mitigation

The recommended mitigation ratios proposed for oak woodland revegetation range from 3:1 for trees less than 6 inches dbh, 4:1 for trees 6 inches to 18 inches dbh to 6:1 for trees greater than 18 inches dbh (Table 3) (Denise Duffy & Associates 2015). This oak woodland revegetation plan is based on the ratios recommended by CDFW with modifications proposed by the District environmental and biological staff. Using these mitigation ratios, a total of 685 mitigation trees will be required for native trees (Table 4). These trees will be mitigated by planting 375 native trees on site and paying in lieu fees to the town of Los Gatos for the balance of the remaining mitigation trees required.

Table 3. Summary of Tree Replacement Ratios for Native Tree Impacts

Size of Tree Removed (dbh, in inches)1

Replacement Ratio (number of trees replaced to number of trees removed)

<6 3:1

6–18 4:1

>18 6:1

1 Diameter at breast height (dbh) is defined as the diameter of the tree at breast height, or the diameter of the tree at 54 inches above existing grade. The dbh of multitrunk trees was calculated as the square root of the sum of all squared trunk stem dbhs.


May 2016

Table 4. Native Tree Impacts and Mitigation

Common Name Size Class (dbh, in inches) Number of Trees Affected Number of Mitigation Trees

Blue oak <6 9 27

Blue oak 6–18 6 24

Subtotal blue oak 15 51

Coast live oak <6 35 105

Coast live oak 6–18 62 248

Coast live oak >18 4 24

Subtotal coast live oak 101 377

Valley oak <6 19 57

Valley oak 6–18 49 196

Subtotal valley oak 68 253

Willow 6–18 1 4

Subtotal willow 1 4

Total 185 685

Note: dbh = diameter at breast height.

If minor impact deviations occur during construction or as design details are added, the number of mitigation plantings will be adjusted to accommodate the resulting increase or decrease in impacts using the same mitigation ratios and design parameters described in this plan. In-kind species replacement is not a requirement. If certain species exhibit higher rates of mortality at the revegetation sites, they may be replaced with species that demonstrate higher growth rates and survival.

3.2.2 Nonnative Tree Replacement Ratios and Mitigation

As described in the Town of Los Gatos Tree Protection Ordinance (Ordinance 2240), nonnative tree replacement ratios will be based on tree canopy size measured as the maximum distance across the canopy (Table 5). Mitigation ratios for in-lieu fee mitigation include all nonnative trees which have a 12-inch or greater diameter. The mitigation ratios are based on tree canopy size measured as the maximum distance across the canopy. The mitigation ratios range from 3:1 to 6:1. Using these ratios, the mitigation trees required for non-native tree removal total 179 (Table 6).


May 2016

Table 5. Summary of Tree Replacement Ratios for In-Lieu Fee Mitigation

Size of Tree Canopy Removed¹ Replacement Ratio2

10–27 feet 3:1

28–40 feet 4:1

40–56 feet 6:1

1 Maximum distance across the canopy. A more recent version of the tree protection ordinance that was adopted in 2015 uses slightly different tree canopy size classes than the ones that were presented in a previous version of the ordinance (more than 10 feet to 25 feet, more than 25 feet to 40 feet, and more than 40 feet to 55 feet). The ranges presented in Table 5 were from the most current version of the tree protection ordinance at the time tree canopy size data were collected.

2 Number of 24-inch box-size trees replaced or purchased to number of trees removed.

Table 6. Nonnative Tree Impacts and Mitigation

Common Name Canopy Class Number of Trees

Removed Number of Replacement Trees

(24-inch Box Size)

Bushy yate 10–27 feet 2 6

Bushy yate 28–40 feet 4 16

Subtotal bushy yate 6 22

California pepper 10–27 feet 2 6

California pepper 28–40 feet 2 8

Subtotal California pepper 4 14

Camphor 28–40 feet 1 4

Subtotal camphor 1 4

Coast redwood 28–40 feet 1 4

Subtotal coast redwood 1 4

Compact blue gum 28–40 feet 1 4

Subtotal compact blue gum 1 4

Corkscrew willow 10–27 feet 1 3

Subtotal corkscrew willow 1 3

Monterey pine 10–27 feet 2 6

Subtotal Monterey pine 2 6

Red flowering gum 10–27 feet 2 6

Subtotal red flowering gum 2 6

Red iron bark 10–27 feet 10 30


May 2016

Common Name Canopy Class Number of Trees

Removed Number of Replacement Trees

(24-inch Box Size)



Subtotal red iron bark 26 102

River red gum 28–40 feet 2 8

River red gum 40–56 feet 1 6

Subtotal river red gum 3 14

Total 47 179

3.2.3 Tree Mitigation Summary

The overall tree mitigation requirements and the breakdown of how the trees will be mitigated is provided in Table 7. The total number of mitigation trees required is 864. These 864 trees will be mitigation via planting 375 native oaks at the oak woodland revegetation area on-site and planting 107 large container trees on-site outside of the oak woodland revegetation area. The remaining 382 trees will mitigated via payment of $95,500 (382 trees × $250/tree) to the Town of Los Gatos forestry fund.

Table 7. Tree Mitigation Summary

Mitigation Required Tree Numbers

Native tree requirements 685

Nonnative tree requirements 179

Total tree mitigation requirements 864

Mitigation Breakdown Tree Numbers

Native oaks planted at oak woodland revegetation site 375

Large container trees planted on-site 107

Town forestry fee payments 382

Total tree mitigation provided 864


May 2016

Section 4. Proposed Revegetation Site

4.1 Location of Revegetation

Oak woodland revegetation will be concentrated in the eastern portion of the RWTP property that does not currently support tree cover (Figures 2 and 3). The revegetation site occupies 2.6 acres and is located east of the RWTP facilities and west of the drying beds. The site was selected because revegetation was judged to be appropriate and feasible at this location and because the site provides a large continuous planting area. The revegetation site will be planted with oak species to expand oak woodland habitat and connect existing oak woodland patches, enhancing movement corridors for wildlife.

4.2 Revegetation Site Ownership Status

The District owns the proposed revegetation site and intends for the area to remain open space in perpetuity.

4.3 Existing Functions and Values of Proposed Oak Woodland Revegetation Site

4.3.1 Soils

Soils on the Project site are mapped as Urban Land-Montavista-Togasara complex, 9–15% slopes (Natural Resources Conservation Service [NRCS] 2014). The Montavista and Togasara series consist of very deep, well-drained soils that formed in alluvium from mixed rock sources. They occur on hills of remnant terraces. Montavista soil is clay loam on southeast-facing 25% slopes under a cover of annual grasses and oaks (NRCS 2014). Togasara soil is gravelly sandy loam on northeast-facing 16% slopes under a cover of annual grasses and forbs (NRCS 2014).

On 13 November 2014, HTH assessed the suitability of soils for revegetation of oak woodland. The horticultural soil parameters of soils in the proposed revegetation area (nonnative annual grassland) were compared with those of adjacent reference soils supporting the target habitat. This assessment involved excavating soil pits to review the physical characteristics of the soils and sending soils samples to a soils laboratory to evaluate soil chemistry and physical properties. The results of our investigation indicate that the physical and chemical characteristics of the soils at the proposed oak woodland mitigation site (currently nonnative annual grassland) are similar to those of the soils at the reference site supporting the target habitat; therefore, the soils are suitable for establishing new oak woodland habitat. Results of the soils investigation are presented in Appendix A.

As mentioned above, the soils in the revegetation site are similar to the soils in the adjacent woodland and the site’s slope gradient and aspect are similar to that of the adjacent oak woodland habitat. Thus, soils, slope and aspect do not appear to be a limiting factor for establishing oak woodland. Oaks may have occurred at the site

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May 2016

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LegendOak Saplings to be ProtectedOak Plantings to Receive New FoliageProtection CagesApproximate Rinconada Water TreatmentPlant BoundaryOak Woodland Revegetation Site (2.63 ac)Topographic Contours with 5-foot Intervals


May 2016

historically and could have been subsequently removed. Grazing and rodent herbivory may have prevented the natural recruitment of oaks following removal. Active planting and control of herbivory will help ensure successful establishment of the target habitat.

4.3.2 Topography and Hydrology

Topography on the revegetation site consists of a generally east-facing slope of approximately 14–45%. An incised drainage channel runs west to east through the middle of the site and conveys minimal flows toward the RWTP drying beds. Average annual precipitation in the region is approximately 21 inches (PRISM Climate Group 2014). Elevations range from approximately 274 to 450 feet North American Datum of 1927.

4.3.3 Vegetation

The vegetation is dominated by nonnative annual grasses. Grass and ruderal species common throughout the site include nonnative ripgut brome (Bromus diandrus), wild oats (Avena barbata), filaree (Erodium sp.), and sheep sorrel (Rumex acetosella). Patches of invasive weeds on the site include Italian thistle (Carduus pycnocephalus), yellow star-thistle (Centaurea solstitialis), bull thistle (Cirsium vulgare), and stinkwort (Dittrichia graveolens). Native plants, including soap root (Chlorogalum pomeridianum), blue-eyed-grass (Sisyrinchium bellum), and oak saplings, are widely scattered on the hillside. No special-status plants were identified in this habitat type, and none are expected to occur there (Denise Duffy & Associates 2015).

4.3.4 Wildlife

The nonnative grassland at the revegetation site provides habitat to a number of common wildlife species, including California ground squirrel (Otospermophilus beecheyi), striped skunk (Mephitis mephitis), California vole (Microtus californicus), and western fence lizard (Sceloporus occidentalis). Nonnative grasslands also provide important foraging habitat for several bird species, including white-tailed kite (Elanus leucurus) and prairie falcon (Falco mexicanus). No special-status wildlife species were observed within the nonnative grassland during field visits (Denise Duffy & Associates 2015); however, special-status bird species, including Cooper’s hawk (Accipiter cooperii) and white-tailed kite, may forage in this habitat type.

4.4 Timing of Habitat Maturation

The revegetation site will begin providing wildlife habitat functions and values during the first few growing seasons. The oak woodland habitat plantings are expected to make progress toward long-term establishment and reproduction within 5 and 10 years of installation. However, the oak woodland habitat will not begin to fully mature until 25 or more years after installation.


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Section 5. Implementation Plan

5.1 Implementation Success

Previous efforts in 1999–2000 to informally enhance the revegetation site (not required by permit) with oak plantings met several challenges. Most notable was intense predation by small mammals and deer, the presence of dry soils, and a lack of resources to implement the level of maintenance needed to facilitate oak tree establishment (Ingols pers. comm.). All of these challenges will be met by use of substantially greater revegetation management actions, including root and foliage protection, irrigation, weed control and intensive maintenance.

The proposed mitigation strategy has a high probability of success. The following factors contribute to the likelihood of success at the revegetation site:

• Installation of large foliage and root protection cages to reduce browse

• Installation of a robust irrigation system adaptively managed to deliver adequate yet minimal water

• Addition of organic soil amendments and mycorrhizal fungi to improve soil conditions within planting holes

• Implementation of weed control measures to reduce plant competition and discourage small mammals from occupying the site

• Compliance with District protocols, best management practices, and other phytosanitary measures to prevent the introduction of plant pathogens (e.g., Phytophthora spp.) to the site1

• Commitment to long-term monitoring and maintenance by the District (5 years)

• The mitigation designers’ experience in the field of habitat revegetation. HTH has designed many successful oak woodland revegetation projects. Furthermore, the construction, maintenance, and monitoring of the revegetation site will be supervised by a qualified biologist.

5.2 Responsible Parties

The Santa Clara Valley Water District is the lead agency for the Rinconada Water Treatment Reliability Improvement Project, and Michael Coleman is the environmental planner assigned to the project and Linda Spahr and Nina Merrill are district biologists assigned to the project. Mike Munson is the District Engineer assigned to the project.

1 On 26 February 2015, plant pathologists sampled roots of two blue oak plantings that were installed at the

revegetation site in 1999–2000 and found no evidence of Phytophthora (Spahr pers. comm. 2015).


May 2016

Michael Coleman, AICP Environmental Planner Santa Clara Valley Water District 5750 Almaden Expressway San Jose, CA 95118-3614 Telephone: 408.630.3096 [email protected]

5.3 Revegetation Site Construction Schedule

The District will prepare detailed revegetation plans and specifications for the Project and will ensure that the acorns are collected in time for installation in fall 2017.

The order of events and approximate schedule for revegetation site construction/installation is provided in Table 8. This schedule is subject to change pending construction coordination with the water treatment plant upgrades.

Table 8. Revegetation Site Construction Events and Schedule

Event Approximate Timing

1. Updated HortScience tree survey/report

2. H. T. Harvey & Associates updates Oak Woodland Report incorporating new HortScience Report data

April 2016

May 2016

3. District issues RFP for plans and specifications of oak woodland planting in mitigation area

4. District Hires Oak Woodland Revegetation Consultant to prepare plans and specifications suitable for public bid process.

5. Consultant working with District input and review prepares revegetation plans and specifications in accordance with this plan and Woodrat Plan

June 2016

November 2016

December 2016–May 2017

6. District prepares Bid Work for Landscape Contraction work June 2017

7. District Receives Bids and selects Contractor for Landscape Construction

July 2017

8. District issues Contractor Notice to Proceed with work August 2017

9. Excavate planting holes and install root protection cages August 2017

10. Install irrigation system August–September 2017

11. Amend planting basin soil with native mycorrhizal fungi August–September 2017

12. Collect and plant acorns as described in the planting plan presented in Section 5.5

September–December 2017


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Event Approximate Timing

13. Mulch planting sites and existing oak seedlings October–December 2017

14. Install foliage protection cages and tree shelters on plantings and existing oak seedlings and saplings

October–December 2017

Coarse woody debris should be placed around the oak woodland restoration and conservation areas at the time of tree removal, if feasible.

5.4 Soil Amendments

The results of a soils investigation indicate that the oak woodland revegetation area soils have low calcium-to-magnesium (Ca:Mg) ratios (less than 1; Appendix A), which are characteristic of serpentine soils. Serpentine soils tend to be low in nutrients, be high in toxic heavy metals, and have a low water-holding capacity compared with nonserpentine soils (Kruckeberg 2006). The adjacent oak woodland soils have similar Ca:Mg ratios (Appendix A). Thus, this low ratio should not be a limiting factor in the establishment of oak woodland within the existing grasslands. However, supplementing the soil with Ca, potassium, and mycorrhizal fungi has been linked to improved plant establishment (Chaudhary and Griswold 2001; Tiedemann and Lopez 2004). To improve tree establishment, an organic amendment, such as composted green waste (approximately 10% by volume, or 2 cubic yards per 1000 square feet) and approximately 1 cup of soil/duff from the adjacent oak woodlands will be added in each planting basin to a depth of 6 inches. The soil/duff harvested from the adjacent oak woodlands should contain fine roots to help ensure inoculation.

5.5 Planting Plan

The success of this revegetation project will rely in part on appropriate species placement. Planting guidelines described below will be adhered to, and a restoration ecologist will inspect/monitor plant installation to maximize revegetation planting success. Species composition, spacing details, and propagule types can be found in Table 9. To help avoid the introduction and spread of Phytophthora ramorum, the plant pathogen that causes sudden oak death, coast live oak should not be planted within 65 feet of any bay laurel (Umbellularia californica) trees located on or adjacent to the revegetation site.


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Table 9. Target Species Composition for the Rinconada Oak Revegetation Site

Common Name Scientific Name On-center

Spacing (feet) Minimum Quantity

Propagule Type

Blue oak Quercus douglasii 19 38 Acorn

Coast live oak Quercus agrifolia 19 113 Acorn

Valley oak Quercus lobata 19 224 Acorn

Total 375

The planting plan is designed to restore a high-quality native oak woodland community as mitigation for Project impacts on native trees. The proposed revegetation includes planting approximately 2.6 acres to accommodate the mitigation replacement trees (Figure 3). The revegetation of oak woodland will expand the existing oak canopy and increase the wildlife habitat value at the site by increasing the contiguous area of oak woodland canopy.

5.5.1 Target Vegetation

The tree species selected for planting at the revegetation site were selected to best reflect the surrounding oak woodland habitat and soil and hydrologic conditions. Valley oak is the dominate tree with approximately 60% of the planting followed by coast live oak at approximately 30% and blue oak at approximately 10%. Valley oak and coast live oak are faster growing species than blue oak and better suited to the relatively deep soils present. Coast live oak represents a relatively small proportion of the trees planted (approximately 30%) as it is susceptible to sudden oak death, which is a plant disease that is of concern in the region.

Trees will be planted in groups by species to encourage development of monospecific stands, as exists in mature stands adjacent to the revegetation site. This will also promote future production of acorns in the planted oak species, which are pollinated by wind and will benefit from pollen sources close to each other. Specific locations for individual plants will be field fit depending on site conditions present.

Conversion of nonnative annual grassland to oak woodland represents a substantial improvement in the overall habitat values of the revegetation site for a variety of wildlife species. It is likely that at least some portion of the proposed oak woodland revegetation site once supported oak woodland. Many thousands of acres of oak woodland habitat have been converted to grasslands as a result of firewood cutting, agricultural practices, and subsequent lack of oak regeneration, and there is no substantial difference between the soils or aspects in areas that support oak woodland habitat and those in adjacent areas that support grasslands (Appendix A).

5.5.2 Seed Procurement

Given the similar physical and chemical characteristics of the soils, HTH recommends that revegetation plants originate from acorns collected from the adjacent oak woodland. Selecting propagules from these plants will help ensure successful establishment and maintain the local genetic diversity and integrity. If adequate propagules cannot be obtained from the adjacent oak woodland, a concerted effort should be made to identify


May 2016

adequate seed sources from a broader area in Santa Clara County with similar soils. Acorns will be harvested from trees during the year in which the site will be planted. Generally, acorns mature in fall between late September and late October. Following collection, damaged acorns will be culled by first placing acorns in a bucket of water. Those acorns that float will be discarded. The remaining acorns will then be visually examined, and the acorns showing any evidence of insect damage or fungal infestation will be discarded. The remaining acorns, especially those collected from off the ground will then be surface sterilized in a bath of cold water and bleach solution and then placed in plastic zip lock bags in a 3:1 mixture of perlite and vermiculite with about 50% acorns and 50% perlite-vermiculite mixture. These acorns will then be stored in a refrigerator until they are ready for planting. If the planting year is not a good acorn year, the planting may be delayed for a year.

5.5.3 Mycorrhizal Inoculation

The soils will be inoculated with native mycorrhizal fungi by incorporating native duff and soil from the adjacent oak woodlands into the top 6 inches of each planting hole at the time of planting.

5.5.4 Seed Installation

Acorns will be installed between late October and December, when rainfall has saturated the soils at the revegetation site. The planting holes should be at least 2 feet in diameter and 3 feet deep. All stones greater than 4 inches in diameter will be removed from the excavated soils. The sides and bottom of each hole should be scarified, and each planting hole should be irrigated before planting and again immediately following planting. Augering must be completed before fall rains wet the soil to field capacity; barely moist soil is preferred.

Temporary, bottomless root protection cages will be installed in half of the planting holes (see Section 5.5.5, “Plant Protection”). Acorns will be installed 1.5 inches below the ground. Acorns will be placed parallel to the soil surface. Two or three acorns will be installed in each planting hole.

A 4-foot-diameter irrigation basin with a 4-inch-high, 4-inch-wide lip will be constructed around each planting site. The basins will be kept weed free to reduce competition for moisture and deter small mammals and mulched to reduce evaporation. The acorns will be irrigated immediately following installation.

5.5.5 Plant Protection

The revegetation site is riddled with small-mammal burrows, and mammal browse from previous oak woodland planting efforts has been severe (Ingols pers. comm.). Browse damage to the oak woodland plantings from deer, rodents, and other wildlife could be severe if protective measures are not taken. Therefore, root protection cages, tree shelters, and foliage protection cages will be installed around the plantings to protect them from predation.

Root Protection Cages. Underground root protection greatly reduces seedling mortality in sites that are heavily infested with gophers (Adams and Weitkamp 1992). Probably the most effective way of protecting young saplings from gophers and other fossorial mammals is to use exclusion cages. Properly installed root


May 2016

protection cages do not negatively affect root development (Adams and McDougald 1995; HTH 2011). Root protection cages will be installed in half (approximately 188) of the planting basins to help determine the effectiveness of root protection cages at the revegetation site. Cages should be large and should extend above the ground (24 inches wide, 18 inches below ground, and at least 6 inches above ground). Cage material should not be heavy galvanized hardware cloth because it requires too much time to rust through. The general idea is for the cage to provide protection while the tree is vulnerable but to rust through before roots become girdled by the cage. To speed up the decomposition process, the root protection cages will be scarified by the contractor before installation to nick/stress the galvanized coating. Additional research will be conducted as part of developing the final root protection design for the project.

Tree Shelters. Because of the past issue with damage by small mammals, additional protection will be provided through the installation of short (12-inch) tree shelters. The shelters will be buried approximately 3 inches deep and will provide additional protection from small-mammal browse near the root crown and lower trunk area of the trees. These short tubes are not expected to cause the plantings to develop the “leggy” form that can be associated with taller shelters.

Foliage Protection Cages. Deer browse is expected to be heavy and has been observed on oak saplings growing on the revegetation site. Therefore, foliage protection cages will be installed on all plantings and naturally recruited oak saplings. The cylindrical cages will be 4 feet in diameter by 5 feet tall. The foliage protection cages will be constructed with welded wire or chicken wire fencing, which will be supported by metal T-posts and will be installed flush to the ground. Protective cages will be installed immediately following planting and will remain around each sapling at least until the vertical stem at the top of the trunk (leader) is above deer browse. The foliage protection cages will be raised as the trees’ leader approaches the top of the cage up until individual trees reach a height of 6–7 feet.

5.5.6 Mulch

Woodchip mulch will be spread at each irrigation basin and at each oak sapling to a minimum depth of 3 inches and at a diameter of 4 feet around the base of each tree. The mulch will serve to control weeds, reduce loss of soil moisture, help to condition the soils, and potentially deter voles. The mulch should be kept a minimum of 2 inches from the stem of the acorns and buckeye seeds. If placed directly up against the woody tissue of a plant, mulch can trap excess moisture and encourage decay organisms that can damage or kill the plant.

5.5.7 Irrigation

An irrigation system will be installed and adaptively managed to provide minimal water to each planting basin to ensure successful establishment of the mitigation plantings. Seasonal irrigation has been shown to improve survivorship, growth rate, and root growth of oak seeds and seedlings (Bernhardt and Swiecki 1991; Young and Evans 2005; Devine et al. 2007). Additionally, water availability under drought conditions may be a limiting factor in establishing oak woodland habitat at the Project site. Considering the large quantity of plants to be installed, it is recommended that the irrigation system be connected to a regular water supply, such as a main water line if possible. A gravity-fed system supplied by a water tank above the planting areas could potentially


May 2016

be used, but it would not be nearly as effective as a mainline-supported system. If sufficient water pressure is available (as in the case using a main water line), it is recommended that the plants be irrigated with a bubbler irrigation system. Bubbler systems are generally more water tight than drip irrigation systems and will attract fewer rodents that can chew on and damage irrigation tubing. In addition, most of the material that makes up a bubbler system is PVC pipe, which is generally resistant to damage by small mammals. Fixed tubing can be placed above ground across the hill slope. Using above-grade irrigation tubing will also minimize disturbance caused by trenching. Flexible hosing can extend from the fixed PVC pipe tubing to the individual planting basins. Flow should be monitored at planting basins at the top of the slopes. Irrigation emitters should be fully adjustable to zero to support varying plant needs.

5.5.8 Natural Recruitment

Approximately 11 naturally recruited oak saplings growing in the revegetation area (Figure 3) will be protected from deer browse and weed competition to encourage growth and canopy development. Foliage protection cages and coarse woodchip mulch will be placed around each sapling according to the methods described above in Sections 5.5.5 and 5.5.6.

5.5.9 Coarse Woody Debris Installation

To increase the structural diversity of the revegetation site and adjoining conservation areas, large limbs and trunks (8 inches in diameter or greater) from trees will be harvested from the impact site, or from an off-site source, and scattered on the revegetation site as both individual pieces and piles. Salvage and placement of the coarse woody debris will provide a complex structure to the revegetation site, which will improve wildlife value. Portions of the coarse woody debris will be partially buried (4–6 inches) to help anchor them in place and provide additional contact with the soil. A restoration ecologist will direct the installation of all coarse woody debris.

5.5.10 Schedule

Acorns will be collected in fall when they are ripe and installed between October and December.


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Section 6. Maintenance Plan

The trees installed in the revegetation area will require maintenance during the first 3–5 years (plant establishment period) to establish and become self-sustaining. Maintenance may include replacement of dead plant material, irrigation, weed control, and plant protection.

Monitoring data collected by the Project’s monitoring biologist will be used to evaluate the success of the revegetation site (see Section 7.0). Information from this monitoring program will provide feedback to direct necessary maintenance and to help ensure the success of the revegetation site.

6.1 Dead Plant Replacement

Some or all dead trees in the fall/winter following the first 3 years of maintenance will be replaced, if requested by the District project manager. The vigor, growth, and survival rates of the species installed will be assessed to inform the selection of replacement plants. Those species that are well adapted to the site and have high health and vigor will be used to replace dead plants only if there is room and the increase in cover is not trending towards meeting the final performance criteria.

6.2 Irrigation

The revegetation plantings will require irrigation during the 3- to 5-year plant establishment period. The irrigation frequency will be reduced gradually during this period to facilitate plant acclimation to the site’s natural moisture regime. In Year 1, the plantings will be irrigated approximately two to four times per month from March through October. Each irrigation period will provide an amount of water sufficient to encourage the development of a deep root system. The irrigation schedule in Year 2 will be based on the water requirements of the plants and is anticipated to be substantially less (approximately one to two times per month), whereas in Years 3–5, little or no irrigation (zero to one time per month) will be required. The irrigation schedule may be modified based on climatic conditions to ensure vigorous plant growth during the summer months and/or times of drought.

The irrigation system should be maintained regularly during the plant establishment period (i.e., through Year 5). Any component of the system not functioning properly will be subsequently repaired as part of regular site maintenance. The maintenance will include a provision that the irrigation system will be continuously checked and kept in good working order. Hand irrigation may also be used to irrigate trees in need of water without delivering irrigation to trees that do not need irrigation. Alternatively, bubblers may be capped for trees that no longer need irrigation.


May 2016

6.3 Weed Control

Competition from nonnative herbaceous vegetation can inhibit establishment of oaks (Adams and McDougald 1995, McCreary and Tecklin 1997). General control of this vegetation can reduce plant competition and discourage small mammals from occupying the site. During the 3- to 5-year plant establishment period, the presence of undesirable plant species will be assessed, and the Contractor will be responsible for removing species that could affect site performance. The irrigation basin around each installed tree and shrub will be kept weed free by maintaining the mulch layer and manually removing (i.e., hand pulling) the weeds that become established in the mulch. Care will be taken to avoid the removal or damage of naturally recruiting woody native vegetation. The maximum height of all weeds within the 4-foot-diameter planting basins will be 6 inches at any time. The basins will be kept weed free for most of the year. The maximum height for all weeds on the site, at any time, will be 18 inches and will be below 12 inches during the growing season (March through October).

Weed control will be accomplished by manual removal and/or the use of herbicide. Consideration should be given to the herbicide’s potential effect on the surrounding vegetation, habitats, and wildlife. Herbicides must always be applied in accordance with all applicable federal, State of California, and local directives and regulations, including the District Pesticide Policy. An overview of California’s licensing requirements for herbicide use may be found online (<http://www.cdpr.ca.gov/docs/license/liccert.htm>).

6.4 Plant Protection

Foliage protection cages and tree shelters will be regularly maintained during the 3- to 5-year plant establishment period. If a plant outgrows its cage before the end of the establishment period, the plant protection will be removed as soon as possible to ensure that the tree grows unhindered. At a minimum, the tree shelters will be removed and disposed of when they start to photodegrade (approximately Year 5). HTH does not anticipate the need to remove the root protection cages because the cages are expected to disintegrate/oxidize within 5–10 years after installation. If it is determined that plant mortality is high in locations where root protection cages were not installed (half the sites) and that mortality resulted from root herbivory, root protection cages will be installed as part of dead plant replacement. If, on the other hand, it is determined that plant mortality is high in locations where root protection cages were installed and that mortality resulted from root girdling caused by the root protection cages, then root protection cages will be removed during dead plant replacement.


May 2016

In January 2011, HTH conducted a field investigation at a riparian habitat revegetation site along Coyote Creek in Santa Clara County to examine potential negative effects of root protection cages on root development 5 years after plant installation (HTH 2011). Two Fremont cottonwood (Populus fremontii) trees fitted with contractor-constructed root protection cages were unearthed. Results of the investigation showed that the root protection cages were effectively protecting against burrowing animals and that they did not damage or restrict the plants’ roots. Both cages were almost completely disintegrated/oxidized (Photograph 1). The cage placed in a location with greater soil moisture oxidized and broke down more rapidly compared to a cage placed in a drier location. Thus, HTH expects the root protection cages installed at the oak woodland revegetation site to sufficiently begin to disintegrate/oxidize within 5–10 years after installation.

6.5 Pruning

Revegetation plants will not be pruned unless specifically required to maintain the health and vigor of the plants. Structural defects in scaffold branches which will lead to later branch break outs and death of the tree will be addressed in years 1–5 as they appear, so resulting pruning wounds can be kept as small and wound closure is speedy. Plants with a substantial insect or disease infestation may require pruning.

6.6 Natural Recruitment

Care will be taken to avoid damaging naturally recruiting native tree seedlings during maintenance and nonnative species removal activities. Maintenance personnel will be trained to differentiate between native and nonnative species. Fostering natural recruitment will aid in rapid habitat development and varied canopy architecture.

6.7 Schedule

The revegetation site will be maintained regularly during the 3- to 5-year plant establishment period. Maintenance activities will occur approximately three times per month during the growing season (March through October) and approximately once per month from November through February. The plant establishment period and associated site maintenance will be extended if significant plant replacement is required because of low plant survivorship.

Photograph 1. A large, deep root system of a five-year-old Fremont cottonwood (Populus fremontii). The contractor-constructed cage is mostly disintegrated.


May 2016

Section 7. Monitoring Plan

7.1 Introduction

Monitoring data will be collected and used to evaluate the success of the revegetation site. Information from this monitoring program will provide feedback to direct necessary maintenance and adjustments to the planting area or techniques to ensure the success of the revegetation site.

The revegetation site will be monitored annually over a five-year period. Performance and final success criteria will be based on tree survival in Years 1–3 and overall site conditions in Years 4 and 5. If the final success criterion in Year 5 is not met, monitoring will continue until it has been met.

7.2 Implementation Monitoring

A qualified restoration ecologist (staff or consultant) will monitor the Project site during construction to ensure that Project impacts are consistent with those outlined in this document and that the revegetation site is installed as described in this plan.

7.3 As-built Plans

Within 8 weeks of the completion of revegetation site construction, a very basic as-built plans will be prepared and submitted to the District. These plans will primarily be used to record the total number of trees originally installed and to establish the photodocumentation points for long-term monitoring. Future analysis of the site will be based on these plans.

7.4 Performance and Final Success Criteria

Site monitoring measurements will be compared to the performance criteria below to evaluate the extent to which the revegetation site is incrementally developing high-quality oak woodland habitat. Performance criteria include tree survival and plant health and vigor in Years 1–3. The overall health of the site will be based on an annual qualitative assessment by an arborist or consultant experienced in oak woodland development in Years 3–5. The goal of this woodland revegetation is not timber production, but habitat expansion. Therefore, emphasis will not be placed on creating high density tree plantings in a grid pattern. Tree cover is desirable but so is overall site health. Sun gaps will allow vegetative complexity which will support wildlife. With that in mind, we propose not to force production from the site by using extraordinary agricultural methods (e.g., deep ripping) or an extensive period of human intervention (e.g., long-term artificial irrigation). The oak woodland development will be guided by the woodland manager/consultant according to the site’s varied physical and biotic character. The carrying capacity in one sector may be quite different than in another. Ultimately, the final success criteria for the site are that by Year 5, the oak density and species selection will be stable, irrigation will be eliminated, and the site will be self-sustaining and healthy.


May 2016

Monitoring to assess performance criteria provides an early indication of site performance but does not necessarily mean the project is a failure nor does it extend the long-term monitoring period if they have not been met. Instead, it serves as an indicator that management practices need to be revaluated and potentially modified to ensure long-term success. Failure to meet final success criteria will result in extension of the overall five-year monitoring period until they are achieved and will require implementation of remedial action measures. If the final success criteria are achieved, the site will be considered a success and monitoring can cease.

7.4.1 Tree Survival

Tree survival will be monitored in Years 1–3. The results of this monitoring will be carefully considered by the District and a plant replacement approach will be developed based on professional judgement which will take into consideration factors such as percent survival, distribution of alive and dead plants, and the causes of mortality.

7.4.2 Site Maintenance

Site maintenance is included in the performance criteria because of the critical importance of proper maintenance during the plant establishment period. Site maintenance monitoring will assess plant replacement, weed control, irrigation, and maintenance of foliage and root protection measures. Site maintenance will be monitored during the plant establishment period. The following are the performance criteria for site maintenance.

Plant Replacement. Dead plants will be replaced between 15 October and 15 January. The acorns will originate from the adjacent oak woodland, or if adequate acorns cannot be obtained from the adjacent oak woodland, a concerted effort will be made to identify adequate seed sources from a broader area in Santa Clara County with similar soils. A written summary of replanting dates, locations, species, and numbers will be included in each monitoring report.

Weed Control. The maximum height of all weeds within the 4-foot-diameter planting basins will be 6 inches at any time. The basins will be kept weed free for most of the year. The maximum height for all weeds on the site, at any time, will be 18 inches and will be below 12 inches during the growing season (March through October).

Irrigation. Irrigation of the revegetation plants will be assessed to determine whether they are being irrigated with regularity sufficient to achieve the plant survival performance and success criteria.

7.5 Monitoring Methods

This section provides details about the methodology that will be used during annual site monitoring.


May 2016

7.5.1 Tree Survival

The survival of plantings will be determined by field counts of all of the original tree planting locations in Years 1–3. An attempt will be made to determine the cause of mortality of all dead trees and that determination will be used to develop a replanting approach.

7.5.2 Health and Vigor

Health and vigor will be assessed in Years 1–3 on all trees. Tree health and vigor will be measured using the numerical and qualitative scale shown in Table 10 by considering such factors as plant color, bud development, new growth, herbivory, drought stress, fungal/insect infestation, and physical damage. Health and vigor for each tree species will be ascertained by averaging the numerical values for each species. In addition, a qualitative measure of the overall health and vigor of the site will be made in Years 1–5, which will include a general assessment of insects, disease, rodent pressure, structural defects requiring corrective pruning, and canopy productivity.

Table 10. Tree Health and Vigor Categories

Qualitative Values Numerical Values Observations

High health and vigor 1–3 67–100% healthy foliage

Medium health and vigor 4–6 34–66% healthy foliage

Low health and vigor 7–9 0–33% healthy foliage

7.5.3 Photodocumentation

Photodocumentation of the revegetation site will be conducted from a number of fixed locations in Years 1–5. Photographs will also be taken to record any event that may significantly affect the success of the revegetation, such as flood, fire, or vandalism. The locations of photodocumentation points will be selected when the as-built plans are developed for the site.

7.6 Monitoring Schedule

The monitoring schedule is presented in Table 11. Monitoring will be conducted at the revegetation site between August and October of Years 1–5.


May 2016

Table 11. Monitoring Schedule for the Rinconada Water Treatment Plant Revegetation Site

Monitoring Task 8 Weeks After Project Installation Ye

ar 1

Year

2

Year

3

Year

4

Year

5

As-built plans no as built X

Tree survival X X X

Tree health and vigor X X X

Overall site health and vigor X X X X X

Photodocumentation X X X X X X

7.7 Adaptive Management

An adaptive management approach will be employed to allow adjustments to maintenance and management practices based on data collected and observations made during annual monitoring and site maintenance. These management modifications, based on hands-on, project-specific experience, will guide revegetation efforts to maximize habitat development and to ensure revegetation site success. Potential remedial actions could include culling trees where density is too high, supplemental watering, additional invasive plant control, additional planting, corrective pruning of structural defects in young scaffold branches, and additional pest control.

7.8 Reporting

Annual data collection will take place from August through October of each monitoring year. Annual monitoring reports will be submitted to the District by 31 December of each monitoring year. Maps showing monitoring locations and copies of photodocumentation will be provided along with the reports. Field data sheets will be available for review upon request.

Reports will be prepared in the following format:

1. Report Summary 2. Introduction 3. Methods 4. Results 5. Discussion 6. Management Recommendations 7. Literature Cited 8. Appendices


May 2016

7.9 Completion of Mitigation

Monitoring will be conducted for at least 5 years at the revegetation site. At the end of the monitoring period, a final monitoring report will be prepared to establish whether the revegetation site has achieved the final success criteria. If the revegetation site has met the final success criteria, a letter will be sent to the District acknowledging the condition of the site and requesting the District’s concurrence that the revegetation obligations have been met. The project will be considered a success by the District and “signed off” when the final success criteria are met in Year 5 at the revegetation site.

7.10 Contingencies and Remedial Actions

If annual performance criteria or final success criteria are not met, the District will prepare an analysis of the cause(s) of failure and implement appropriate remedial actions.

7.11 Statement of Financial Commitment

The District is financially responsible for the successful mitigation of impacts on trees from the construction of the Project, including long-term monitoring and any remedial actions. The District will be responsible for all Project tree mitigation, permitting, oversight, monitoring, and funding (including meeting required success criteria). Shifting of this financial responsibility would require approval by District.


May 2016

Section 8. References

Adams, T. E. and N. K. McDougald. 1995. Planted blue oaks may need help to survive in southern Sierras. California Agriculture 49:13–17.

Adams, T. E. and W. H. Weitkamp. 1992. Gophers love oak––to death. California Agriculture 46:27–29

Bernhardt, E. A. and T. J. Swiecki. 1991. Minimal input techniques for valley oak restocking. U.S. Department of Agriculture Forest Service General Technical Report PSW-126.

[CDFW] California Department of Fish and Wildlife. 2014. Comments on the Draft Environmental Impact Report. Subject: Rinconada Water Treatment Plant Reliability Improvement Project, Draft Environmental Impact Report, SCH #2014012012, Santa Clara County. 7 November 2014.

Chaudhary, B. and M. Griswold. 2001. Mycorrhizal fungi—a restoration practitioner’s point of view. Ecesis 11:6–7.

Denise Duffy & Associates. 2015. Final Environmental Impact Report: Rinconada Water Treatment Plant Reliability Improvement Project. September. SCH# 2014012012. Project# 993294057. San Jose, California. Prepared for Santa Clara Valley Water District, San Jose, California.

Devine, W. D., C. A. Harrington, and L. P. Leonard. 2007. Post-planting treatments increase growth of Oregon white oak (Quercus garryana Dougl. ex Hook.) seedlings. Restoration Ecology 15:212–222.

HortScience. 2006. Tree Report: Rinconada Water Treatment Plant 1st & 2nd Utility Alignment Alternatives. 19 September. Los Gatos, California. Prepared for Santa Clara Valley Water District, San Jose, California.

HortScience. 2015. Draft Arborist Report: Rinconada Water Treatment Plant Rehabilitation, Los Gatos, California. Pleasanton, California. Prepared for H. T. Harvey & Associates, Sacramento, California.

HortScience. 2016. Arborist Report: Rinconada Water Treatment Plant Rehabilitation, Los Gatos, California. Pleasanton, California. Prepared for H. T. Harvey & Associates, Sacramento, California.

[HTH] H. T. Harvey & Associates. 2011. U.S. 101/Baily Avenue Interchange Riparian Mitigation Project 2010 (Year-5) Annual Monitoring Report. 25 January. Los Gatos, California. Project No. 1668-09. Prepared for City of San José Department of Public Works, San Jose, California.

ICF International. 2012. Final Santa Clara Valley Habitat Plan, Santa Clara County, California. August. San Jose, California. Prepared for City of Gilroy, City of Morgan Hill, City of San Jose, County of Santa Clara, Santa Clara Valley Transportation Authority, and Santa Clara Valley Water District.


May 2016

Ingols, Judy. Revegetation Supervisor. Santa Clara Valley Water District. 30 October 2014—e-mail correspondence with Tara Pozzi of Santa Clara Valley Water District regarding why the blue oaks planted as enhancement at the restoration site did not grow well.

Kruckeberg, A. R. 2006. Introduction to California Soils and Plants: Serpentine, Vernal Pools, and Other Geobotanical Wonders. California Natural History Guides. University of California Press, Berkeley, California.

McCreary, D. and J. Tecklin. 1997. Effects of seedling protectors and weed control on blue oak growth and survival. Pages 243–250 in N. Pillsbury, J. Verner, and W. Tietje (Technical Coordinators), Proceedings of a Symposium of Oak Woodlands: Ecology, Management, and Urban Interface Issues. March 19–22, 1996. San Luis Obispo, California. U.S. Department of Agriculture Forest Service General Technical Report PSW-GTR-160.

[NRCS] Natural Resources Conservation Service. 2014. Web Soil Survey. [online]: http://websoilsurvey.nrcs.usda.gov/. Accessed 17 October 2014.

PRISM Climate Group. 2014. PRISM Climate Data. [online]: http://prism.oregonstate.edu. Accessed 5 December 2014.

Spahr, Linda. Santa Clara Valley Water District. 17 March 2015––e-mail correspondence with Mike Coleman, Mike Muson, and Tara Pozzi regarding the results of Phytophthora monitoring at the Rinconada Water Treatment Plant oak mitigation plant.

Tiedemann, A. R. and C. F. Lopez. 2004. Assessing soil factors in wildland improvement programs. Restoration Western Ranges and Wildlands 1:39–56.

Young, T. P. and R. Y. Evans. 2005. Initial mortality and root and shoot growth of oak seedlings planted as seeds and as container stock under different irrigation regimes. Native Plants Journal 6:89–90.

Zink, T. A. and M. F. Allen. 1998. The effects of organic amendments on the restoration of a disturbed coastal sage scrub habitat. Restoration Ecology 6:52–58.

Final Rinconada Water Treatment Plant Upgrades Oak Woodland Mitigation Plan A-1 H. T. Harvey & Associates

May 2016

Appendix A. Soils Information

1331 Garden Highway, Suite 310- Sacramento, CA 95833 Ph: 916.779.7350 F: 916.779.7371

Memorandum

Project# 3270-45

4 December 2014 To: Michael Coleman, Santa Clara Valley Water District From: Patrick Reynolds, H. T. Harvey & Associates Subject: Rinconada Water Treatment Plant Oak Mitigation Project—Suitability of Soils for Oak

Woodland Restoration

Overview

H. T. Harvey & Associates (HTH) assessed the suitability of soils for restoration of oak woodland at the Rinconada Water Treatment Plant Oak Mitigation Project (Project) site in Los Gatos, California (Figure 1). The horticultural soil parameters of soils in the proposed restoration area (nonnative annual grassland) were compared with those of adjacent reference soils supporting the target habitat. This assessment involved excavating soil pits to review the physical characteristics of the soils and conducting a detailed soil laboratory analysis to evaluate soil chemistry and physical properties.

Soils on the Project site are mapped as Urban Land-Montavista-Togasara complex, 9–15% slopes (Natural Resources Conservation Service [NRCS] 2014a). The Montavista and Togasara series consist of very deep, well-drained soils that formed in alluvium from mixed rock sources. They occur on hills of remnant terraces. Montavista soil is clay loam on southeast-facing 25% slopes under a cover of annual grasses and oaks (NRCS 2014a). Togasara soil is gravelly sandy loam on northeast-facing 16% slopes under a cover of annual grasses and forbs (NRCS 2014a).

Soil Sampling Methods

On 13 November 2014, HTH restoration ecologists Patrick Reynolds, M.S., Matt Quinn, M.S., and Charles McClain, M.S., excavated 12 soil pits at the Project site: 5 in oak woodlands and 7 in the proposed oak woodland planting area (Figure 2). The soil pits were excavated to a depth of 18–34 inches. At each soil pit, HTH recorded slope, aspect, dominant plant species, rooting depth, soil texture and color, and percent rock content. Data forms and representative photographs are presented in Appendices A and B.

Sources: Esri, HERE, DeLorme, USGS, Intermap, increment P Corp.,NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand),TomTom, MapmyIndia, © OpenStreetMap contributors, and the GIS UserCommunity

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Rinconada Water Treatment Plant Upgrades OakWoodland Management Plan Soil Assessment(3270-45)

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Rinconada Water Treatment Plant Upgrades OakWoodland Management Plan Soil Assessment(3270-45)

LegendProposed Restoration Area

Soil Pits by HabitatOak WoodlandGrassland

4 H. T. HARVEY & ASSOCIATES

Soil samples for laboratory analysis were obtained from the top 18 inches of each soil profile. Soils from each habitat types were combined into two composite samples. Fruit Growers Laboratory in Santa Paula, California, then conducted comprehensive analytical analyses of each samples. The analyses included the following physical and chemical metrics important for tree growth and establishment: soil texture, pH, salinity, calcium-to-magnesium (Ca:Mg) ratio, and sodium absorption ratio (SAR). Each of these metrics is described in greater detail below. Results of the analyses were evaluated by Talus Soil Consulting, in Santa Cruz, California (Appendix C).

Soil Texture

Soil texture (i.e., percent sand, silt, and clay content) affects permeability, water-holding capacity, and plant rooting potential, among other factors (Brady and Weil 2002). Coarse soils high in sand content are more permeable and have a lower water-holding capacity than fine-textured soils high in clay. For this reason, soil texture directly influences plant growth and establishment.

pH

Soil pH is a measure of soil acidity/alkalinity. Soil pH values between approximately 5 and 7 are most amenable for establishing the target oak woodland habitat (NRCS 2014b).

Salinity

Soil electrical conductivity (ECe) is an indirect measurement of soil salinity. As such, ECe is useful for determining whether soil is too saline to support plant growth and establishment. Soil ECe is tightly coupled with soil pH, but in a general sense, most nonhalophytic plants are tolerant of ECe values ranging from 0 deciSiemens per meter (dS/m) to approximately 8 dS/m.

Ca:Mg Ratio

Soil Ca:Mg ratio is also an important soil parameter. There is, however, indecision as to the direct role of soil Ca:Mg ratio on plant growth and establishment (Simon et al. 1979; Carran 1991). It is more generally accepted that the Ca:Mg ratio affects plant growth and establishment indirectly through its influence on soil structure (Emerson 1983). Generally speaking, high levels of Ca are not problematic to plant health, although excessive levels of Ca can negatively affect the uptake and use of other essential elements (e.g., phosphorous). Ca:Mg ratios on lands supporting robust vegetative growth vary considerably, and it is not possible to identify a most appropriate Ca:Mg ratio for revegetation purposes. In this case, it is more appropriate to compare ratios in the proposed restoration area (currently nonnative annual grassland) with adjacent reference soils supporting the target habitat.


Sodium Absorption Ratio

SAR takes into account the fact that the adverse effect of soil sodium is moderated by the presence of Ca and Mg ions. As a result, a low SAR value (i.e., ≤40) is generally agreeable for nonhalophytic plant growth and establishment (Brady and Weil 2002). For this reason, species with greater salinity tolerance often perform better in soils with higher SAR values.

Results

Oak woodland locations were dominated by blue oak (Quercus douglasii), coast live oak (Quercus agrifolia), valley oak (Quercus lobata), toyon (Heteromeles arbutifolia), and a sparse understory of nonnative annual grasses, primarily wild oat (Avena barbata) and ripgut grass (Bromus diandrus) (Appendix B, Photo 1). Slopes ranged from 2:1 (rise over run) to 5:1, and aspect ranged from east-southeast to south-southeast. The texture of the oak woodland soil was gravelly sandy clay loam (Appendix B, Photo 2). Soil pH was slightly acidic, and salinity and SAR were low. The Ca:Mg ratio was less than 1, which is characteristic of serpentine soil (Table 1).

Table 1. Physical and Chemical Soil Properties

Habitat Texture pH ECe

(dS/m) SAR Ca:Mg Ratio

Oak woodland Gravelly sandy clay loam

6.6 0.5 0.6 0.76

Grassland (proposed oak woodland planting area)

Gravelly clay loam 6.2 0.3 0.6 0.62

Notes: ECe = soil electrical conductivity; dS/m = deciSiemens per meter; SAR = sodium absorption ratio; Ca:Mg = calcium to magnesium.

Nonnative annual grassland locations were dominated by wild oat and ripgut grass (Appendix B, Photo 3). Slopes ranged from 3.5:1 to 5:1, and aspect ranged from northeast to southeast. The texture of the grassland soil was gravelly clay loam (Appendix B, Photo 4). Soil pH was slightly more acidic in the grassland soil than in the oak woodland soil (Table 1). Soil salinity and SAR were low and similar to levels measured in the oak woodland. The Ca:Mg ratio was slightly lower in the grassland than in the oak woodland.

Horticultural Suitability Conclusions

The results of our investigation indicate that the physical and chemical characteristics of the soils at the proposed oak woodland mitigation site (currently nonnative annual grassland) are similar to those of the soils at the reference site supporting the target habitat; therefore the soils are suitable for establishing new oak woodland habitat. Both areas are located on similar slopes with similar aspects. The grassland soil has less sand and more silt and clay (finer particles) than the soil supporting the target oak woodland habitat, indicating higher water- and nutrient-holding capacities, which could be helpful for oak seedling establishment. Although


the grassland soil is slightly more acidic than the oak woodland soil, both values fall within the range preferred by oaks (NRCS 2014b). Salinity levels are safely low and similar in both areas, and the SARs are the same in both habitat types. The grassland and oak woodland soils have low Ca:Mg ratio (less than 1) which are characteristic of serpentine soils. Serpentine soils tend to be low in nutrients, be high in toxic heavy metals, and have a low water-holding capacity compared with nonserpentine soils (Kruckeberg 2006). However, the oak woodland and grassland soils having similar Ca:Mg ratios. Thus, this low ratio should not be a limiting factor in the establishment of oak woodland within the existing grasslands.

Recommendations

HTH recommends that restoration plants originate from propagules (seeds, acorns) collected from the adjacent oak woodland given the soil chemistry results. The trees and shrubs that make up the adjacent oak woodland are adapted to the similar soils present in the proposed restoration area. Selecting propagules from these plants will help ensure successful establishment and maintain the local genetic diversity and integrity. If adequate propagules cannot be obtained from the adjacent oak woodland, a concerted effort should be made to identify adequate seed sources from a broader area in Santa Clara County with similar soils.

Most plants that grow in serpentine soil are adapted to low soil fertility; however, supplementing the soil with Ca and potassium has been linked to improved plant establishment (Tiedemann and Lopez 2004). Oak tree establishment in the proposed restoration area would be improved by adding an organic amendment, such as composted green waste, at planting. Talus Soil Consulting recommends adding approximately 10% by volume, or 2 cubic yards per 1000 square feet, of compost in each planting basin to a depth of 6 inches (Appendix C). The slight increase in nutrients from the compost would improve establishment of oak woodland at the proposed oak woodland restoration area.

Finally, periodic irrigation for 2–3 years or more is recommended to ensure adequate establishment. Several different irrigation methods could be used to irrigate the plantings. The preferred method would be a bubbler system which is relatively easy to maintain and resistant to damage by small mammals which are present in large numbers on site.


References

Brady, N. C., and R. R. Weil. 2002. The Nature and Properties of Soil. 13th edition. Prentice Hall, Upper Saddle River, New Jersey.

Carran, R. A. 1991. Calcium magnesium imbalance in clovers: a cause of negative yield response to liming. Plant and Soil 134:107–114.

Emerson, W. W. 1983. Inter-particle Bonding in Soil: An Australia Viewpoint. CSIRO Division of Soils. CSIRO Publishing, Melbourne, Victoria, Australia.

Kruckeberg, A. R. 2006. Introduction to California Soils and Plants: Serpentine, Vernal Pools, and Other Geobotanical Wonders. California Natural History Guides. University of California Press, Berkeley, California.

[NRCS] Natural Resources Conservation Service. 2014a. Web Soil Survey. [online]: http://websoilsurvey.nrcs.usda.gov/. Accessed 17 October 2014.

[NRCS] National Resources Conservation Service. 2014b. The Plants Database. [online]: http://plants.usda.gov/. Accessed 2 December 2014.

Simon, C. R., R. B. Corey, and M. E. Sumner. 1979. Effect of varying Ca:Mg ratios on yield and composition of corn (Zea mays) and alfalfa (Medicago sativa). Communications in Soil Science and Plant Analysis 10:152–162.

Tiedemann, A. R., and C. F. Lopez. 2004. Assessing soil factors in wildland improvement programs. Restoration Western Ranges and Wildlands 1:39–56.

A-1 H. T. HARVEY & ASSOCIATES

Appendix A. Data Forms

B-1 H. T. HARVEY & ASSOCIATES

Appendix B. Representative Photographs of the Study Area


Photo 1. Oak woodland habitat at soil pit 2.

Photo 2. Gravelly sandy clay loam soil in

oak woodland habitat at soil pit 2.


Photo 3. Nonnative annual grassland in the proposed oak

woodland planting area at soil pit 7.

Photo 4. Gravelly clay loam soil in the

proposed oak woodland planting area in soil pit 7.

C-1 H. T. HARVEY & ASSOCIATES

Appendix C. Soil Report by Talus Soil Consulting

www.talussoil.com • PO Box 8004 Santa Cruz, California 95061 • 408-859-9726

December 1, 2014

HT Harvey & Associates

1331 Garden Highway

Sacramento, CA 95833

Attn: Patrick Reynolds

Re: Rinconda Water Treatment Plant/Oak Mitigation Project Data from soil report SP 1413407-001 analyzed by Fruit Growers Laboratory, Inc. was evaluated. The Oak Woodland sample is established oak and grassland areas. The Grassland sample is an area where oak woodland restoration has been proposed and is need of recommendations for seedling installation. Data is attached. Data Comparison and Recommendations

The established Oak Woodland and potential area for oak mitigation (Grassland) are fairly similar in many

respects. In regard to chemistry, the Grassland area is slightly more acidic in pH than the Oak Woodland area (pH

6.2 versus 6.6, respectively), but both values fall within the range preferred by oaks. Salinity (ECe) is safely low for

both areas and similar at 0.3 dS/m for the Grassland and 0.5 dS/m for the Oak Woodland. The SAR’s (sodium

adsorption ratios) are equal at 0.6 suggesting the same sodium to calcium and magnesium content in each. Of

interest is the calcium to magnesium ratios in the soils. The Grassland has a Ca:Mg of 0.62 and the Oak Woodland

has a Ca:Mg of 0.76. When this ratio falls below 1, soils are considered serpentine. The Grassland is slightly more

serpentine than the Oak Woodland, but this difference is not likely to greatly influence establishment. It is

recommended that the oak seedlings selected for planting originate from an area with similar serpentine

properties. The best option would be those from the site itself. Plants selected for the site should have tolerance

to serpentine soils. A plant list of those can be found at this site: http://www.laspilitas.com/advanced/serpentine-

plants.html.

The fertility data demonstrates similar levels of most nutrients. Phosphorus and boron is slightly lower in the

Grassland than Oak Woodland sample, but it is not recommended to adjust these nutrients at this time. Most

serpentine plants are adapted to lower fertility in the soil. However, improvements in calcium and potassium

availability have been linked to improved plant establishment. These slight increases in nutrient availability have

been the result of adding an organic amendment such as composted greenwaste at planting. Approximately 10%

by volume or 2 cubic yards per 1000 square feet to a depth of 6 inches been shown to be beneficial in restoration

plantings. The slight increase in nutrients from the compost has not been problematic for weed introduction as

the Ca:Mg ratio is not favorable for many weeds. Compost suitability could be evaluated once a material is

selected.

In regard to the physical properties, the textures are slightly different between the Oak Woodland and Grassland

sample. This is evident in the small difference in CEC’s as well where the Oak Woodland sample has a CEC of 19.7

meq/100g and the Grassland sample measured 22.4 meq/100g. The Oak Woodland sample is an extremely

gravelly sandy clay loam while the Grassland sample is an extremely gravelly clay loam. The gravel content is

similar, which is beneficial. The Grassland has less sand and more silt and clay (finer particles), which could be

helpful for establishment of the seedlings. Having more fine particles allows for a higher water and nutrient

holding capacities. The soil available water is important especially during establishment.

Due to the three year drought that California has endured, the amount of water in the subsoil has been drastically

depleted. Oaks rely on this deep water storage during the year, as the Mediterranean climate does not provide

much precipitation from May until November. To assist with establishment, it is recommended to provide periodic

www.talussoil.com • PO Box 8004 Santa Cruz, California 95061 • 408-859-9726

supplemental irrigation for the first two to three years. This additional soil moisture is especially important as

drought conditions continue to persist despite recent precipitation events.

If I can be of any additional assistance, please feel free to contact me.

Best regards,

Meagan Hynes, PhD, CPSS

[email protected]

Corporate Offices & Laboratory853 Corporation StreetSanta Paula, CA 93060TEL: (805)392-2000Env FAX: (805)525-4172 / Ag FAX: (805)392-2063CA ELAP Certification No. 1573

Office & Laboratory2500 Stagecoach RoadStockton, CA 95215TEL: (209)942-0182FAX: (209)942-0423CA ELAP Certification No. 1563

Office & Laboratory563 E. Lindo AvenueChico, CA 95926TEL: (530)343-5818FAX: (530)343-3807CA ELAP Certification No. 2670

Office & Laboratory9415 W. Goshen AvenueVisalia, CA 93291TEL: (559)734-9473FAX: (559)734-8435CA ELAP Certification No. 2810

Office & Laboratory3442 Empresa Drive, Suite DSan Luis Obispo, CA 93401TEL: (805)783-2940FAX: (805)783-2912CA ELAP Certification No. 2775

ENVIRONMENTAL AGRICULTURALAnalytical Chemists

Lab ID : SP 1413407-001November 26, 2014

Customer ID : 2-24904Talus Soil Consulting, LLCAttn: Meagan M. HynesP.O. Box 8004Santa Cruz, CA 95061

Sampled On : November 14, 2014Sampled By : Patrick ReynoldsReceived On : November 17, 2014Depth : N/A

Description :Oak WoodlandProject :Rinconda Water Treatment/Oak Mitigation Project

GENERAL SOIL ANALYSIS

Test Description Result Units Optimum Range Graphical Results Presentation

Primary NutrientsVeryLow

ModeratelyLow

Optimum ModeratelyHigh

VeryHigh

Nitrate-Nitrogen 2.9 PPM 13 - 33

Phosphorus-P2O5 11.5 PPM 59 - 82

Potassium-K2O (Exch) 217 PPM 93 - 560

Potassium-K2O (Sol) 9.6 PPM 40 - 130

Secondary NutrientsCalcium (Exch) 1660 PPM 2400 - 3200

Calcium (Sol) 32 PPM 53 - 190

Magnesium (Exch) 1310 PPM 240 - 480

Magnesium (Sol) 42.7 PPM 7.5 - 48

Sodium (Exch) 40 PPM 0.0 - 230

Sodium (Sol) 20 PPM 0.0 - 200

Sulfate 34.0 PPM 59 - 1000

Micro NutrientsZinc 3.5 PPM 1.2 - 40

Manganese 23.0 PPM 2.4 - 60

Iron 59.5 PPM 10 - 70

Copper 14.0 PPM 0.27 - 40

Boron 0.16 PPM 0.33 - 1.5

Chloride 20.2 PPM 4.8 - 210

CEC 19.7 meq/100g 14 - 35

% Base SaturationCEC - Calcium 42.1 % 60 - 80

CEC - Magnesium 54.8 % 10 - 20

CEC - Potassium 2.30 % 1.0 - 6.0

CEC - Sodium 0.868 % 0.0 - 5.0

CEC - Hydrogen < 1.00 % 0.0 - 3.0StronglyAcidic

ModeratelyAcidic

NearNeutral

ModeratelyAlkaline

StronglyAlkaline

pH 6.58 --- 6.5 - 7.5

3%

25%

57%

14%

Good Problem Indicates physical conditions and/or phenological and amendment requirements.

November 26, 2014 Lab ID : SP 1413407-001Customer ID : 2-24904

Talus Soil Consulting, LLC Description : Oak Woodland



OthersSatisfactory Possible

ProblemModerateProblem

IncreasingProblem

Soil Salinity 0.47 dS/m 0.0 - 2.0

SAR 0.6 0.0 - 6.0

Limestone < 0.10 % 0.0 - 0.500 1 2 3 4 5 6

Lime Requirement 0 Tons/AF ---

Gypsum Requirement < 0.50 Tons/AF ---VeryLow

ModeratelyLow


VeryHigh

Moisture 6.4 % 3.7 - 26LoamySand

SandyLoam

Loam SiltLoam

ClayLoam

Clay Organic

Saturation 36.8 % 40 - 50


Note: Soils with gypsum requirements over 10 tons should be applied incrementally at a maximum of 10 tons per acre per year and reanalyzedyearly after each application.

Soil pH & Limestone levels are important to consider when making plant selections. Soil pH levels above 7.0 are notsuitable for acid loving plants. Soils containing limestone are not suitable for plants sensitive to Limestone.

FRUIT GROWERS LABORATORY, INC.

SB1:JRJScott Bucy, Director of Ag. Services







Lab ID : SP 1413407-002November 26, 2014

Customer ID : 2-24904Talus Soil Consulting, LLCAttn: Meagan M. HynesP.O. Box 8004Santa Cruz, CA 95061

Sampled On : November 14, 2014Sampled By : Patrick ReynoldsReceived On : November 17, 2014Depth : N/A

Description :Grass LandProject :Rinconda Water Treatment/Oak Mitigation Project



Primary NutrientsVeryLow

ModeratelyLow


VeryHigh

Nitrate-Nitrogen 4.3 PPM 16 - 36

Phosphorus-P2O5 < 4.6 PPM 60 - 82

Potassium-K2O (Exch) 193 PPM 100 - 630

Potassium-K2O (Sol) 4.8 PPM 43 - 140

Secondary NutrientsCalcium (Exch) 1680 PPM 2700 - 3600

Calcium (Sol) 17 PPM 63 - 210

Magnesium (Exch) 1630 PPM 270 - 540

Magnesium (Sol) 25.5 PPM 10 - 54

Sodium (Exch) 40 PPM 0.0 - 260

Sodium (Sol) 16 PPM 0.0 - 160

Sulfate 20.0 PPM 66 - 1000

Micro NutrientsZinc 2.2 PPM 1.4 - 40

Manganese 22.8 PPM 2.7 - 61

Iron 52.9 PPM 12 - 72

Copper 10.2 PPM 0.31 - 40

Boron 0.05 PPM 0.36 - 1.6

Chloride 14.2 PPM 5.5 - 220

CEC 22.4 meq/100g 14 - 35

% Base SaturationCEC - Calcium 37.5 % 60 - 80

CEC - Magnesium 59.8 % 10 - 20

CEC - Potassium 1.88 % 1.0 - 6.0

CEC - Sodium 0.826 % 0.0 - 5.0

CEC - Hydrogen < 1.00 % 0.0 - 3.0StronglyAcidic

ModeratelyAcidic

NearNeutral

ModeratelyAlkaline

StronglyAlkaline

pH 6.20 --- 6.5 - 7.5

3%

23%

56%

19%


November 26, 2014 Lab ID : SP 1413407-002Customer ID : 2-24904

Talus Soil Consulting, LLC Description : Grass Land



OthersSatisfactory Possible

ProblemModerateProblem

IncreasingProblem

Soil Salinity 0.30 dS/m 0.0 - 2.0

SAR 0.6 0.0 - 6.0

Limestone < 0.10 % 0.0 - 0.500 1 2 3 4 5 6

Lime Requirement 0 Tons/AF ---

Gypsum Requirement < 0.50 Tons/AF ---VeryLow

ModeratelyLow


VeryHigh

Moisture 6.0 % 4.1 - 29LoamySand

SandyLoam

Loam SiltLoam

ClayLoam

Clay Organic

Saturation 41.1 % 40 - 50


Note: Soils with gypsum requirements over 10 tons should be applied incrementally at a maximum of 10 tons per acre per year and reanalyzedyearly after each application.

Soil pH & Limestone levels are important to consider when making plant selections. Soil pH levels above 7.0 are notsuitable for acid loving plants. Soils containing limestone are not suitable for plants sensitive to Limestone.

FRUIT GROWERS LABORATORY, INC.

SB1:JRJScott Bucy, Director of Ag. Services







Reviewed andApproved By Scott Bucy

Digitally signed by Scott BucyTitle: Director of Agricultural ServiDate: 2014-11-21

Lab ID : SP 1413407-001November 21, 2014Customer ID : 2-24904

Talus Soil Consulting, LLCAttn: Meagan M. HynesP.O. Box 8004Santa Cruz, CA 95061

Sampled On : November 14, 2014-:Sampled By : Patrick ReynoldsReceived On : November 17, 2014-14:00Matrix : Soil

Description :Oak WoodlandProject :Rinconda Water Treatment/Oak Mitigation Project

Sample Results - Ag

Constituent Result PQL Units NoteSample PreparationMethod Date/ID

Sample AnalysisMethod Date/ID

Physical Char.BPa

% Sand 50.0 0.5 % CSSS47.3 11/20/14:213744 CSSS47.3 11/21/14:217759

% Silt 20.5 0.5 % CSSS47.3 11/20/14:213744 CSSS47.3 11/21/14:217759

% Clay 29.5 0.5 % CSSS47.3 11/20/14:213744 CSSS47.3 11/21/14:217759

Soil Texture Sandy Clay Loam

Sieve # 1 9.5 mm 24.6 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 2 6.3 mm 11.9 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 4 4.75 mm 7.7 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 10 2.0 mm 19.3 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 14 1.4 mm 5.7 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 20 849 um 0.1 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 35 500 um 10.6 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 40 425 um 1.8 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 60 250 um 4.4 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 100 150 um 4.0 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 140 106 um 2.3 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 200 75 um 1.7 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 325 45 um 2.2 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Receiving Pan 3.8 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

ND=Non-Detected. PQL=Practical Quantitation Limit. Containers: (BPa) Bag - Paper Preservatives: N/A







Reviewed andApproved By Scott Bucy

Digitally signed by Scott BucyTitle: Director of Agricultural ServiDate: 2014-11-21

Lab ID : SP 1413407-002November 21, 2014Customer ID : 2-24904

Talus Soil Consulting, LLCAttn: Meagan M. HynesP.O. Box 8004Santa Cruz, CA 95061

Sampled On : November 14, 2014-:Sampled By : Patrick ReynoldsReceived On : November 17, 2014-14:00Matrix : Soil

Description :Grass LandProject :Rinconda Water Treatment/Oak Mitigation Project

Sample Results - Ag

Constituent Result PQL Units NoteSample PreparationMethod Date/ID

Sample AnalysisMethod Date/ID

Physical Char.BPa

% Sand 35.0 0.5 % CSSS47.3 11/20/14:213744 CSSS47.3 11/21/14:217759

% Silt 30.5 0.5 % CSSS47.3 11/20/14:213744 CSSS47.3 11/21/14:217759

% Clay 34.5 0.5 % CSSS47.3 11/20/14:213744 CSSS47.3 11/21/14:217759

Soil Texture Clay Loam

Sieve # 1 9.5 mm 15.2 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 2 6.3 mm 13.5 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 4 4.75 mm 8.0 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 10 2.0 mm 23.2 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 14 1.4 mm 7.3 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 20 849 um 0.2 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 35 500 um 13.4 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 40 425 um 1.9 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 60 250 um 4.3 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 100 150 um 3.5 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 140 106 um 1.9 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 200 75 um 1.4 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Sieve # 325 45 um 2.0 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

Receiving Pan 4.3 0.1 % D422 63 11/20/14:213745 SA1:7-2 11/20/14:217761

ND=Non-Detected. PQL=Practical Quantitation Limit. Containers: (BPa) Bag - Paper Preservatives: N/A

Documents

Prepared for: Michael Coleman, AICP · 2019. 8. 26. · 1331 Garden Highway, Suite 300 Sacramento, CA 95833 Ph: 916.779.7300 F: 916.770.7371. Final Rinconada Water Treatment Plant