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NW Fishletter #384, August 1, 2018

[8] Corps Responds To Detroit Reservoir Drawdown Concerns In Scoping Responses

A proposal by the U.S. Army Corps of Engineers to build a fish collection facility and a temperature control tower on Detroit Dam near Salem drew nearly 200 comments with a full spectrum of concerns, now summarized in a report, released July 16.

The 40-page analysis of comments, and the Corps' responses to them, complete the scoping process for the Detroit Downstream Passage Project. The agency will now use those comments to help prepare a draft Environmental Impact Statement (EIS), which the agency expects to release next year.

The proposed facilities on the North Santiam River address some of the requirements in a 2008 Biological Opinion for the Willamette Valley Project, which includes 13 multipurpose dams. All are used for flood control, and eight are hydroelectric projects with a combined capacity of 409 MW and an average combined generation of 167 MWh annually, which is sold by the Bonneville Power Administration.

Corps spokesman Jeffrey Henon said in an email that since they are still evaluating different alternatives, it's too early to know what the impacts on power generation will be. But if an alternative with a deep drawdown is chosen, Detroit Dam, with a generating capacity of 100 MW, would not be able to produce power at all during construction; and Big Cliff Dam, with a generating capacity of 18 MW, may also be impacted due to reduced flow rates. Other reservoirs may also need to be drafted faster than normal through the summer, in order to meet minimum flow targets throughout the Willamette River.

The Biological Opinion found that Detroit Dam, with a generating capacity of 100 MW, is jeopardizing Endangered Species Act-listed upper Willamette River spring Chinook salmon and steelhead. It requires the Corps to provide downstream passage for juvenile fish and control the river's temperature to more closely reflect pre-dam conditions. The dam has caused cooler downstream temperatures in the spring and summer, and warmer temperatures in the fall and winter.

To build the fish collection facility and temperature control tower, the Corps is considering five alternatives, including its "No Action" alternative. One alternative involves building the project under regular reservoir levels, and three require a "deep" drawdown of the reservoir for up to two years.

In a March news release, Corps environmental resource specialist Kelly Janes said that the safest, easiest and highest-quality construction method for the temperature control tower would be to draw down the reservoir for the entire construction period. "However, due to the concerns we are hearing, we are looking at ways we can construct this to minimize impacts, which could include no drawdown--a job that would be the most dangerous, difficult and expensive."

A deep drawdown would impact an estimated 250,000 people, including businesses, farmers and the City of Salem, which relies on the reservoir as its primary supply of drinking water for 190,000 customers. Farmers in the area estimated the financial loss of crops at more than $2.45 million, the Corps' news release said.

Many of the scoping comments focused on impacts from alternatives that would draw down the reservoir for as long as two years. Impacts to summer tourism, Salem's water supply and farmers who need the water to irrigate crops were just some of the concerns outlined in 198 comments, which were summarized under 33 different code headings and provided with a brief response. The responses are considered preliminary, and concerns will be fully addressed in the draft EIS, the report says.

The Detroit Dam is a barrier to ESA-listed salmon and steelhead. Photo by Karim Delgado, courtesy of U.S. Army Corps of Engineers.

"Per NEPA (National Policy Act) requirements, the EIS effects analysis will assess the direct, indirect, and cumulative effects of the alternatives on a variety of resources including, but not limited to socioeconomic conditions, recreation, water supply, water quality, public safety, biological communities, air quality, traffic, cultural resources, aesthetics etc. within the affected area," one of the Corps' responses says.

Most of the comments--159 of them--came from unaffiliated individuals, and the rest from businesses, organizations, city and county governments, state and federal agencies and a few elected officials.

According to the Corps' analysis, 164 of the comments had to do with the proposed alternatives. Socioeconomic impacts were high on the list and included 49 comments concerned with water supply, 40 with recreation, 29 with agriculture, and 10 or fewer concerned with reservoir fisheries, the downstream biological community, boater safety, fire safety, flood risk, hydropower, traffic and aesthetics.

The report said that 42 of the comments indicated support for the project, while 29 were in opposition. Further, 69 of the comments supported a specific alternative while 43 opposed a specific alternative.

Several of the comments quoted in the report recommended alternatives that could reduce the length of time a drawdown would be necessary. Many asked about constructing the project only in the winter; but, the Corps responded in the report, that alternative was assessed and screened out due largely to winter flooding.

There were also concerns about impacts of the project itself, and the potential for water quality issues similar to those experienced at PGE's Pelton Round Butte Facility, currently under litigation.

Twelve of the summarized comments were from WildEarth Guardians, Native Fish Society and Northwest Environmental Defense Council--three groups that filed a lawsuit against the Corps and National Marine Fisheries Service in March, claiming the Corps has failed to meet many of the deadlines in the Willamette Valley Project's 2008 Biological Opinion, and that the agencies should redo it. -K.C. Mehaffey

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Publisher/Editor-in-Chief: Mark Ohrenschall, Editor: K.C. Mehaffey
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