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Response to Comment R5-70The salinity impacts resulting in a shift to a brine fly- and brine shrimp-based ecosystem have already been described. It is not known if thedecreased loads (but selectively increased input concentrations) oftoxic constituents will result in significantly changed surface sedimentconcentrations. Sediment exposure to the food chain (throughinvertebrates to birds) will change, in general, with the changinginvertebrate community. The possibility that more surface sedimentswill be resuspended should not change the sediment exposure routes inthe near-shore littoral regions. In particular, as the sea shifts to a brinefly dominance, the larvae and pupae will aggregate in extremelyshallow shoreline environments which are always wave washed andturbid. Project impacts that may cause enhanced mid-water sedimentconcentrations should have no significant effect on that nearshorecommunity.

Response to Comment R5-71The Draft EIR/EIS has been revised to more specifically address effectsto double-crested cormorants from reductions in the water surfaceelevation of the Salton Sea. These revisions are found in this FinalEIR/EIS in subsection 3.2.4.3 under Section 4.2, Text Revisions.

In addition, the revised Salton Sea Conservation Strategy would avoidaccelerating exposure of nesting/roosting features and changes in fishabundance. See the Master Response for Biology Approach to SaltonSea Habitat Conservation Strategy in Section 3 in this Final EIR/EIS.

Response to Comment R5-72As described in responses to comments R5-67, R5-68, and R5-70, thebest available data do not suggest that a shallower Sea will result inenhanced sediment resuspension (over its already well-mixed state) orthat enhanced mixing (should it occur) will act to enhance toxicity fromsediment-associated chemicals. A future Sea dominated by brineshrimp feeding on midwater algae and brine flies feeding in extremeshoreline algae mats would not be expected to be significantly affectedby sediment-bound toxins in the water column.

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Response to Comment R5-73Areas currently used by snowy plovers for nesting will become farther removed from the water as the water surface elevation of the Salton Sea declines. A decline in the water surfaceelevation is projected to occur under both the Proposed Project and the No Project alternative. Thus, to the extent that distance to water influences suitability of breeding sites for snowyplovers, existing nesting areas will become unsuitable under both the Proposed Project and the No Project alternative and therefore is not an impact attributable to the ProposedProject.The commenter suggests that at a reduced sea elevation, near shore areas will be too steep to be suitable for snowy plover nesting. Bathymetric data show a general pattern ofincreasing acreage of shallow sloped areas with declining surface elevation (see response to comment G25-82). At most of the lower elevations, the amount of shallow sloped areas (asindicated by acreage less than 1 foot) is greater than at the current elevation. This information suggests that suitably sloped areas would be available for snowy plovers at lowerelevations.

Impacts of the Proposed Project are assessed relative to the No Project alternative. As described under the No Project alternative, snags in the Salton Sea that are currently surroundedby water would no longer be surrounded by water as the water surface elevation declines. Herons and egrets could abandon use of snags as nesting and roosting sites when they areno longer surrounded by water. This effect could occur under both the No Project and the Proposed Project, the only difference being that it could happen 3 years earlier under theProposed Project. Thus, the potential for abandonment of snags as nesting and roosting sites is not a consequence of the Proposed Project and therefore is not considered a significantimpact of the Proposed Project. Further, herons and egrets are known to nest in snags and trees that are not surrounded by water (Kaufman 1996; Shuford et al. 2000), suggesting thatbirds may continue to use snags at the Salton Sea when they are no longer surrounded by water. Finally, with implementation of the Salton Sea Conservation Strategy, the accelerationof exposure of nesting/roosting sites would be avoided. See the Master Response on Biology Approach to Salton Sea Habitat Conservation Strategy in Section 3 in this Final EIR/EIS.

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Response to Comment R5-74There is no reason to expect that basic processes of uptake andprecipitation that serve to limit water-borne selenium concentrations inthe Sea will be significantly altered by the projected increase in salinity.Selenium that enters the Sea is quickly reduced to selenite andincorporated into fine sediments and settled biomass (Setmire andSchoeder 1998). Such bacterial reduction processes will not beeliminated by projected increases in selenium. In fact, selenium loss insaline evaporation ponds has been specifically attributed to saline-tolerant algae populations (Fan and Higashi 1998).

In addition, the biomagnification that occurs in current Salton Sea biota(Setmire and Schroeder 1998) would be reduced in a future, morelimited ecosystem by the elimination of a fish-based food chain. Birdexposures should be reduced by the shift to an all-invertebrate diet oflowered average tissue selenium concentrations (as compared topredatory fish tissues).

Response to Comment R5-75The bathymetric data are not accurate enough to precisely predict theamount of shallow water habitat in the 4-15 cm depth range. However,they do reasonably predict changes in the amount of habitat of lessthan 1 foot depth, some of which would be in the 4-15 cm rangepreferred by shorebirds. The area less than 1 foot deep provided anindex of the possible dynamics of shallow water habitat and constitutedthe best available quantitative information.

The amount of shallow water habitat (< 1 foot deep) would increaseunder the Baseline from 1,143 acres at an elevation of -227 ft msl toabout 3,600 acres at -235 ft msl. The Proposed Project would show asimilar pattern. Although the perimeter of the Sea would decrease to 83miles, the amount of shallow water habitat would increase to about3,200 acres at -246 ft msl. The bathymetry analysis indicates that boththe Baseline and Proposed Project would increase the amount ofshallow water/mudflat habitat to a similar degree relative to existingconditions. There is no indication that there will be a net loss of shallowwater/mudflat area under either the Baseline or Proposed Projectconditions.

Existing shallow water/mudflat habitat could be lost or reduced incertain areas as the Sea recedes. These existing areas would be lost at

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Response to Comment R5-75 (continued)the same rate under the Proposed Project and No Project alternative. Also, under both alternatives, new areas of shallow water/mudflat habitat would also be created at lowerelevations. As the shallow impounded areas at the southern and southeast side of the Sea are lost due to elevation declines, new shallow impounded areas will likely be created eitherin the vicinity or in other areas of the Sea. Conversion of drains into gravity-flow systems will allow water from the drains to flow naturally to the Sea. The drains likely would create "mini-deltas" at each outlet as the water spreads out and meanders to the Sea. Foraging habitat for shorebirds could improve under this situation by (1) an increase in the amount of shallowwater/mudflat habitat, and (2) creation and maintenance of lower salinity areas where a greater diversity of invertebrates can persist. As shorebirds are mobile and able to utilizedifferent areas as habitat conditions become suitable, it is unlikely that negative impacts to shorebirds will occur as shallow water/mudflat areas shift locations.

In areas along the southern portion of the Sea, barnacle bars and other topographic variations back up drainwater and create small, shallow impoundments where shorebirds forage. Tothe degree that water from the Sea also contributes to determining the extent and depth of these impoundments (i.e., creates a backwater effect), the extent of inundation andcharacteristics of these areas could change as the Sea recedes. These potential changes would occur under both the Proposed Project and Baseline.

At the north end of the Sea, there could be a net reduction in the amount of shallow water/mudflat habitat. The topography of the seabed is much steeper than at the south end of theSea. Thus, as the Sea recedes and the total length of shoreline becomes smaller, the amount of mudflat/shallow water habitat would decline. This effect would be greater under theProposed Project than the Baseline. However, the Whitewater River could create a more extensive delta with greater amounts of shallow water/mudflat habitat as its discharge spreadsout as the Sea pulls away from the river mouth. Increased flow from the CVWD Service Area could enhance this effect.

Under both the Proposed Project and Baseline, shallow water/mudflat habitat could be lost or reduced as the Sea recedes, but under both alternatives, new areas of shallowwater/mudflat habitat also would be created as the Sea recedes. Because the magnitude and likelihood of changes in amount and characteristics of shallow water/mudflat habitat, eitherpositively or negatively, does not differ between the Proposed Project and Baseline, the Proposed Project would not significantly affect the availability of this habitat type. All of thesepotential impacts to shallow water/mudflat habitat are described under Impact BR - 49. The analysis was based on the best available information on the bathymetry of the Sea and thepotential changes in Sea elevation under the Proposed Project.

Response to Comment R5-76It is not clear that a shallower Sea will be more productive. Total nutrient loading will be reduced with the conservation program and possible enhanced resuspension of surfacesediments could contribute nutrients to stimulate more algae growth. Alternatively, suspended sediments may reduce average light exposure to the algae community and thus reduceproductivity (light reduction to algae is a likely result of enhanced mixing of the water column, and is exacerbated by entrained sediment). In addition, the change in productivity of theSea in relation to decreased average depth is likely to be insignificant as the Sea is now and has always been highly eutrophic. Regardless, as discussed in the text, there is no knownquantitative link between Sea productivity and avian disease that would allow us to predict changes in incidence of disease (even if we could predict changes in the Sea's productivity).

Response to Comment R5-77Please refer to the Master Response on Biology Approach to the Salton Sea Habitat Conservation Strategy.

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Response to Comment R5-78Approach 1, which included stocking tilapia in the Salton Sea andconstructed ponds, has been eliminated from consideration. SeeMaster Response for Biology—Approach to Salton Sea HabitatConservation Strategy in Section 3 of this Final EIR/EIS.

Response to Comment R5-79Please refer to the Master Response on Biology Approach to theSalton Sea Habitat Conservation Strategy.

Response to Comment R5-80See Master Response on Biology Approach to Salton Sea HabitatConservation Strategy in Section 3 of this Final EIR/EIS.

Native tree habitat likely would not be created in the seabed exposedby the receding Salton Sea because, as the commenter notes, the soilsare not likely to be suitable. (If soils and water quality are suitable, theHCP Implementation Team [IT] could locate native tree habitat in areasof exposed seabed). Rather, native tree habitat most likely would becreated in natural riparian systems such as along San Felipe Creek orin conjunction with managed marsh habitat created in the ImperialValley. IID would work with the HCP IT to identify the location forcreating native tree habitat and the specific design characteristics withapproval required from the USFWS and CDFG for implementation. TheHCP includes a monitoring and adaptive management program toensure that created native tree habitat is developing and functioning asdesired, or to identify whether management actions are necessary.

If there is a net loss in the amount of tamarisk scrub habitat, IID couldcreate native tree habitat (see Salton Sea - 3 in Chapter 3 of the HCP).IID could elect to create native tree habitat prior to or after a loss oftamarisk scrub habitat. As explained in Salton Sea - 2, if IID createsnative tree habitat prior to a loss of tamarisk scrub, there would be noshort-term reduction in habitat value. Alternatively, IID could createnative tree habitat after documenting a net loss of tamarisk scrub. Inthis case, IID would create three times the acreage that would berequired if IID created the habitat prior to documenting a loss. If IIDcreates habitat after documenting a decline, there would be a short-term reduction in the availability of tamarisk scrub habitat. A short-termreduction could have significant impacts if tamarisk scrub habitat is a

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Response to Comment R5-80 (continued)limiting factor for a species. Tamarisk scrub is an invasive, non-native plant that provides poor habitat quality for wildlife. Given its abundance in the Project Area (more than 7,000 acresquantified) and poor quality, it is not likely to be a limiting factor for any wildlife species, and a short-term reduction would not be expected to result in population-level effects.

Response to Comment R5-81With the implementation of the Salton Sea Habitat Conservation Strategy as described in the Master Response on Biology Approach to Salton Sea Habitat Conservation Strategy (inSection 3 of this Final EIR/EIS), the elevation of the Salton Sea will not begin to decline until at least the Year 2030, and the ultimate elevation under the Proposed Project would beapproximately -240 ft msl, reducing the surface area of the Salton Sea by approximately 16,000 acres (or 25 square miles). This is one-quarter of the reduction that was projected underHCP Approach 1. As the commenter states, primary recreation use of the Sea is associated with the fishery. The Salton Sea Habitat Conservation Strategy mitigates Project impacts tofish. Since it can be assumed that recreation use would decline under the Baseline once fish are no longer able to reproduce, the Project impacts associated with the decline in surfacearea are still not considered to be significant.

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Response to Comment R5-82With implementation of the Salton Sea Habitat Conservation Strategy,no additional area of the seabed would be exposed beyond thatprojected for the Baseline until the year 2035. After 2035, the additionalexposed area of seabed would be reduced by approximately 16,000acres or 25 square miles. Mitigation measures included in the DraftEIR/EIS recommend relocation of camping and boating facilities toassure continued opportunities for those recreation activities. Thegreatest additional width of exposed area would be along the southernportion of the Sea, where slopes are gentlest.

Response to Comment R5-83Mitigation Measure R-7 specifies that if the elevation of the Seadeclines, boat launching facilities and access to them must be relocatedas the Sea declines to provide ongoing boat launching opportunities.The relocation of these facilities may be temporary and ongoing untilthe Sea reaches its minimum and stable elevation, at which pointpermanent facilities must be provided. When the Project is approved,IID must adopt a Mitigation and Monitoring Plan which will specify whois responsible for implementation of mitigation measures. Therelocation of boat launching facilities is the responsibility of IID.

With implementation of the Salton Sea Habitat Conservation Strategy,the elevation of the Salton Sea would remain stable until the year 2030,at which point the Sea would begin to decline below the Baselineelevation until it reaches approximately -240 ft msl. As stated above, IIDwould be responsible for maintaining ongoing boat launchingopportunities as the Sea declines.

Mitigation Measure R-7, has been revised to reflect that elevationchanges would also occur with the HCP Approach 2 (Salton SeaHabitat Conservation Strategy). See subsection 3.6 under Section 4.2,Revised Text in this Final EIR/EIS.

Response to Comment R5-84Mitigation Measure R-10 specifies that if elevation of the Sea declines,camping facilities and access to them must be relocated as the Seadeclines to provide ongoing boat launching opportunities. Therelocation of these facilities may be temporary and ongoing until theSea reaches its minimum and stable elevation, at which point

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Response to Comment R5-84 (continued)permanent facilities must be provided. When the Project is approved, IID must adopt a Mitigation and Monitoring Plan which will specify who is responsible for implementation ofmitigation measures. The relocation of camping facilities is the responsibility of IID.

With implementation of HCP Approach 2 (now referred to as Salton Sea Habitat Conservation Strategy), the elevation of the Salton Sea would remain stable until the year 2030, atwhich point the Sea would begin to decline below the Baseline elevation until it reaches approximately -240 ft msl. As stated above, IID would be responsible for maintaining ongoingcamping opportunities as the Sea declines.

Mitigation Measure R-10 has been revised to reflect that elevation changes would also occur with implementation of the Salton Sea Habitat Conservation Strategy. See subsection 3.6under Section 4.2, Revised Text, in this Final EIR/EIS.

Response to Comment R5-85Please refer to the Master Response on Air Quality Salton Sea Air Quality Monitoring and Mitigation Plan in Section 3 of this Final EIR/EIS.

Response to Comment R5-86Comment noted.

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Response to Comment R5-87Please refer to the Master Response on Air Quality Applicability ofGeneral Conformity Requirements to the Proposed Project orAlternatives in Section 3 of this Final EIR/EIS.

Response to Comment R5-88Please refer to the Master Response on Air Quality Wind Conditionsat the Salton Sea in Section 3 of this Final EIR/EIS.

Response to Comment R5-89Please refer to the Master Response on Air Quality Wind Conditionsat the Salton Sea in Section 3 of this Final EIR/EIS.

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Response to Comment R5-90Please refer to the Master Response on Air Quality Wind Conditionsat the Salton Sea in Section 3 of this Final EIR/EIS.

Response to Comment R5-91Please refer to the Master Response on Air Quality Wind Conditionsat the Salton Sea in Section 3 of this Final EIR/EIS.

Response to Comment R5-92Commenter notes that Figures 3.7-1 through 3.7-3 illustrate thelocations of monitoring stations in the Project region, rather thanFigure 3.7-4 as noted in the Draft EIR/EIS. The previous Draft EIR/EIShas been revised to reflect this concern. This change is indicated in thisFinal EIR/EIS in subsection 3.7 under Section 4.2, Text Revisions.

Response to Comment R5-93Please refer to the Master Response on Air Quality Applicability ofGeneral Conformity Requirements to the Proposed Project orAlternatives in Section 3 of this Final EIR/EIS.

Response to Comment R5-94Please refer to the Master Response on Air Quality Applicability ofGeneral Conformity Requirements to the Proposed Project orAlternatives in Section 3 of this Final EIR/EIS.

Response to Comment R5-95Please refer to the Master Responses on Air Quality−−Applicability ofGeneral Conformity Requirements to the Proposed Project orAlternatives and Air Quality−−Consistency with the StateImplementation Plan for PM10 in Section 3 of this Final EIR/EIS.

Response to Comment R5-96Please refer to the Master Response on Air Quality Emissions fromConstruction of Conservation Measures in Section 3 of this FinalEIR/EIS.