Bull trout Salvelinus confluentus are native to the McKenzie Basin


	*Minimizing Risks and Mitigation of Impacts to Bull Trout Salvelinus confluentus* from Construction of Temperature Control Facilities at Cougar Reservoir, Oregon.**	Please download Java(tm).
Mark Wade, Project Leader : m.g.wade@worldnet.att.net Vince Tranquilli, Asst. Project Leader: mailto:v_tranquilli@hotmail.com *Chad Helms, Experimental Biology Aide*

Bull trout, Salvelinus confluentus, are native to the McKenzie Basin and inhabit Cougar Reservoir and the South Fork McKenzie above the reservoir. The Columbia River distinct population segment, which includes McKenzie River bull trout, was listed as threatened under the ESA in June of 1998. Construction of the temperature control facilities required lowering the reservoir below minimum pool, reducing the area from 1260 acres to approximately 106 acres from April 2002 through December 2004. Because drafting the reservoir could adversely affect the bull trout population, the Corps funded this study to minimize impacts of construction on bull trout. To protect this population, we needed to understand the movement and habitat use of bull trout in the South Fork McKenzie watershed, and to develop an emergency plan should environmental conditions become detrimental to the overall health of the population.


During spring and summer, the sun warms the surface water of Cougar Reservoir, but water near the bottom remains cold. Because the intakes for the powerhouse and regulating outlet are deep, the South Fork of the McKenzie River below the dam was unnaturally cold druing the summer, blocking salmon migration and reducing productivity in the river below the dam.
During the fall and early winter as the reservoir level dropped, warm surface water reached the intakes. Water released from the dam was unnaturally warm causing chinook salmon eggs to hatch several months early decreasing their survival.
The USACE modified the intake tower by building a 302 foot tall wet well. There are three slots in the wet well, each equipped with three overlapping gates. The gates slide up and down allowing selective withdrawal of water from various levels of the reservoir. The water is mixed to the desired temperature and discharged through the existing penstock and regulating outlet. This enables the Corps to control the temperature of the water discharged below the dam, and reduce impacts in South Fork McKenzie River and McKenzie River downstream of the project.

Turbidity Pictures

Cougar Reservoir drawdown pictures

Cougar Dam Tunnel Tap (Feb 23, 2002)

Other Information:

23 mm, half duplex, PIT tag systems (ODFW)

Upper Willamette bull trout (ODFW Springfield)

Cougar Temperature Control Project (USACE)

Cougar Reservoir flow and pool elevation (NOAA-NWRFC)

Cougar Reservoir elevation graphic (USACE)

Turbidity levels on the South Fork McKenzie below Cougar Dam (USGS)

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*Progress Reports*
*FY 2001*	*FY 2002*	*FY 2003*	*FY 2004*
	Oct. - Dec. Quarterly	Oct. - Dec. Quarterly	Oct. - Dec. Quarterly
Jan. - Mar. Quarterly	Jan. - Mar. Quarterly	Jan. - Mar. Quarterly	Jan. - Mar. Quarterly
Apr. - June Quarterly	Apr. - June Quarterly	Apr. - June Quarterly	Apr. - June Quarterly
July - Sept. Quarterly	July - Sept. Quarterly	July - Sept. Quarterly	July - Sept. Quarterly
Annual Report	Annual Report	Annual Report	Annual Report

Other Reports

Monitoring of Downtream Fish Passsage - Taylor 2000