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Norman BuccolaHolly Bellringer

March 21, 2018Willamette Basin Mercury TMDLAdvisory Committee MeetingTangent, Oregon

PORTLAND DISTRICT WATER MANAGEMENTWILLAMETTE BASIN, OREGONCOTTAGE GROVE AND DORENA DAMS

OVERVIEW

–History of Dams and Flooding

–Locations & Missions

–Annual Regulation: Flood Management & Conservation Storage

–Daily Regulation

–Regional Coordination

–Cottage Grove and Dorena

FLOOD CONTROL ACTS HISTORY

Oregon Flood of Jan 1853

The Great Flood of Dec 1861 – Jan 1862 (WA, OR, CA, ID, NV, NM, AZ, UT)

Willamette Flood of June 1894

1936 – Congress passed Flood Control Act authorizing Corps to survey the Willamette Basin

1938 – Flood Control Act authorized five storage reservoirs

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1894 flood, downtown Portland, Willamette River

1861 Great Flood, downtown Sacramento, CA

HISTORY (CONTINUED)

1940 – Corps began construction of Fern Ridge and Cottage Grove dams

1950 and 1962 Flood Control Acts authorized additional structures

Willamette Flood of Feb 1964 (*FDP ~ $514M)

1969 – Hills Creek constructed (last of the authorized dams in the Willamette)

Willamette Flood of Jan – Feb 1996, (*FDP ~ $1.1B)

*FDP = Flood Damages Prevented

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Construction of Dexter Dam 1954

Construction of Foster Dam 1968

1943 WILLAMETTE VALLEY FLOOD

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Oregon State Archives, Oregon Water Resources Department, OWR0085

WILLAMETTE FLOOD OF 1996

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WILLAMETTE VALLEY, SUB-BASIN SIZE AND LOCATION

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Santiam SubbasinDetroit/Big CliffGreen Peter/Foster

McKenzie SubbasinCougarBlue River

Middle Fork Willamette SubbasinHills CreekLookout Point/DexterFall Creek

AUTHORIZED PURPOSES

–Flood Control–Fish & Wildlife–Irrigation–Hydropower–Recreation–Water Quality–Navigation–Municipal & Industrial Water Supply

* Not all projects are authorized for hydropower

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WATER CONTROL DIAGRAM

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FLOOD RISK MANAGEMENT

Willamette Valley Dams have prevented $26 billion in flood damages

Total project controls 27% of the runoff area in the Basin

Flood reduction occurs annually, typically each winter

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Spilling at Lookout Point Dam – Jan 2006

FLOOD SEASON GOALS

Major flood control season (Nov – Feb)Flood Risk Mitigation

–When a storm hits, keep downstream control points below bank full if possible by storing water.

–After the storm is over, safely evacuate the water stored behind the dams in order to get ready for the next storm.

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FLOOD CONTROL STORAGE

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0

50

100

150

200

250

300

350

400

Hills Creek

Lookout Point

Dexter Fall Creek

Cottage Grove

Dorena Cougar Blue River

Fern Ridge

Green Peter

Foster Detroit Big CliffAvai

labl

e St

orag

e (t

hous

ands

of a

cre-

feet

)

Available Flood Control Storage by Project

Total Flood Control Storage is 1.8 Million Acre FeetCottage Grove + Dorena is 0.1 Million Acre Feet

Cottage Grove Dorena

ENVIRONMENTAL STEWARDSHIP

Stewardship for critical habitat and ESA – listed species including:

–Winter steelhead–Spring Chinook salmon–Bull trout–Fender’s blue butterflies–Kincaid’s lupine–Western pond turtles–Red-legged frogs–Migratory songbirds–Oregon Chub

(delisted May 2015 first fish delisting in the nation)

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FISHERIES GOALS

Minimize stranding–Daily and hourly ramping rates

Prevent dewatering of eggsOperate to provide downstream juvenile passageOperate to control downstream water temperaturesProvide spawning, incubation and rearing flowsMeet Biological Opinion requirements

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RECREATION

–Over 3.5 million annual visitors

–$100 million in economic benefits annually

–3 campgrounds, 23 day-use areas, and 7 boat ramps managed by the Corps

–19 campgrounds, 32 day-use areas, 27 boat ramps, and 8 marinas managed through lease agreements

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Detroit Lake

Cottage Grove Lake

CONSERVATION SEASON GOALS

Balance the needs of the multiple purposes–Refill so there is sufficient water to meet authorized purposes–Provide stored water through the release season for fisheries enhancement and water supply

while minimizing impacts to recreation and other authorized purposes–Meet or exceed downstream flow targets–Achieve downstream temperature targets below Cougar, Detroit and Lookout Point

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CHALLENGES RELATED TO METHYLATED MERCURY

–Cottage Grove and Dorena Lakes

–Flood season and conservation season limit flexibility in lake levels

–Seasonal wetting and drying of bank sediments led to more methylation of mercury at Cottage Grove Lake (Eckley, et.al., 2017)

–Management/infrastructure changes at these lakes involves discussion of trade-offs

Eckley, C., T. Luxton, J. Goetz AND J.McKeman, 2017. Water-level fluctuations influence sediment porewater chemistry and methylmercury production in a flood-control reservoir. David Carpenter, and Eddy Zeng (ed.), ENVIRONMENTAL POLLUTION Elsevier Science Ltd, New York, NY, 222:32-41, (2017).

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SUMMARY

–Dams in the Willamette Valley provide many services to Oregon

–Regulation of these dams is interesting, important work

–Regional coordination occurs daily/seasonally

–People benefit from the results – recreation, power, water supply, flood level reduction

–We’ve adjusted operations and infrastructure for better environmental stewardship

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FOR MORE INFORMATION:

–Reservoir ops during drought: http://www.nwp.usace.army.mil/Missions/Water/Drought.aspx

–River Levels: (Northwest River Forecast Center) http://www.nwrfc.noaa.gov/

–About the Corps: (Portland District web site)www.nwp.usace.army.mil

–Portland District Public Affairs Office:503-808-4510

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