News Release
| Release Number: | 97-115 |
| Dated: | 10/23/1997 |
| Contact: | Public Affairs Office, 503-808-4510 |
Portland, Ore. -- The Portland District, U.S. Army Corps of Engineers, is scoping a study of two options for lowering the reservoir behind John Day Dam, 215 miles upstream from the Pacific Ocean on the Columbia River.
Congress has given the District a 90-day assignment: develop a scope of work for studying the impacts of drawdown of the John Day reservoir. Congress will use this document to decide whether the Corps should be asked to evaluate drawdown of the 77-mile-long reservoir.
Lowering reservoirs behind the dams to levels that are substantially below the normal operating range is called drawdown. Lowering the water level would decrease the width and depth of the reservoir (cross-section), which would increase water velocity. Increased water velocity could move juvenile fish through the reservoir more quickly, thus mimicking their historic journey downriver. This may increase survival rates.
Congress has directed that the Corps limit this potential study of drawdown to two options: "spillway crest" and "natural river level." During the initial 90-day-period, the Corps will discuss drawdown impacts and ask for input from various regional interest groups, state and federal agencies.
Some of the material that will be used to develop the scope of work was gathered in 1994, when the Corps was asked to study drawdown of the John Day reservoir to Minimum Operating Pool (MOP). Normally, the reservoir is held at elevation 265 (normal pool). MOP would lower the reservoir to elevation 257, spillway crest to elevation 210 and natural river to about elevation 165.
The scope currently directed by Congress will detail the requirements for identifying economic and social impacts of the spillway crest and natural river options. Congress could use this scope of work to decide whether or not the Corps should further study spillway crest and natural river drawdown options, or whether one or both concepts should be shelved at this time.
The Study, if approved by Congress, would be divided into two phases. In the first phase, the Corps would begin to identify the impacts - economic and social - including the estimated costs of each. During the first phase, which could start sometime in 1998, workshops would be held to gather information from the public.
The second phase would examine how the two alternatives would be implemented, including potential physical modifications to the dam. It would likely include an Environmental Impact Statement (EIS), related National Environmental Policy Act (NEPA) coordination, and public comments.
The scope of work will identify the social and economic impacts of both drawdown options, and estimate the extent of work required to fully assess each area of impact and associated costs. In the study, the Corps would detail impacts on irrigation, fisheries, wildlife, flood damage reduction, hydropower production, navigation, transportation, cultural resources, recreational activities and water supply, as well as hydraulics and hydrology affects, and associated structural changes at John Day Dam. The Corps would identify a preferred alternative for congressional consideration.
At spillway crest drawdown, project fish passage systems would have to be modified and there would be affects on other users of the river. At natural river, the river could be rerouted to bypass the dam completely. There would be dramatic effects on navigation, transportation, irrigation, recreation, hydropower production, cultural resources and water supplies.
Neither this scope of work nor any potential study will include actual physical modifications at the John Day Dam or study of lowering the reservoir to Minimum Operating Pool (MOP).