News Release
| Release Number: | 03-128 |
| Dated: | 8/4/2003 |
| Contact: | Heidi Y. Helwig, 503-808-4510 |
Portland, Ore.-The public now can view documents on the web explaining how the U.S. Army Corps of Engineers will operate Cougar Reservoir during ongoing construction.
The final Supplemental Information Report (SIR) and environmental assessment (EA) amendment are complete and available on the Corps' website at www.nwp.usace.army.mil/issues/wrtcp. The documents describe planned reservoir operations during temperature control tower construction at Cougar Reservoir on the South Fork of the McKenzie River and their respective environmental impacts.
The Corps distributed a draft copy of the SIR and EA amendment in January after it completed a thorough technical review of its operating practices at Cougar Reservoir. The draft copy explained how the Corps would modify the way it regulates water releases from Cougar Reservoir during construction to lessen impacts on recreation and tourism caused by turbid water, said Corps project manager George Miller. Six written comments were received on the Corps' proposal; these comments, including three from the public, and the Corps' response to them, are incorporated in the final documents. The Corps also held a public meeting to discuss the documents on Feb. 12, 2003.
Primarily, the draft documents explained how modified operations-such as drawing the pool down to about elevation 1,400 feet rather than elevation 1,375 feet-would prevent a repeat of the high levels of turbidity that occurred in 2002. Additional operating requirements also are included in the documents.
Shortly after the draft documents were released, a rainstorm-related slope failure occurred. To manage the failure and subsequent turbidity, the Corps raised the pool elevation to 1,450 feet and has maintained that elevation. The final documents address this change.
The increased turbidity in 2002 did not cause any long-term negative impacts to fish or aquatic insects below the dam. The Corps also found that no levels of contaminants above EPA levels of concern were detected in waters below the dam, though low levels of DDT were detected in the sediment within the reservoir.
The WTCP includes construction of a multi-level intake tower at the dam. The tower will allow the Corps to draw water from differing depths in the reservoir, mixing it to the optimum water temperature for release below the dam to more closely match natural conditions needed by fish. The changes will improve river conditions for salmon and resident fish in the McKenzie and South Fork McKenzie rivers.