Cougar Reservoir (Lane)
Reachcode: 17090004007144 | Area: 1129.3 acres | Shoreline: 17.4 mi | View on Interactive Map
(From Atlas of Oregon Lakes, Johnson et al. 1985). Cougar Lake is a long, narrow multi-purpose reservoir, built by the Corps of Engineers in 1963 by damming the South Fork of the McKenzie River about three miles south of Rainbow. The lake was named Cougar because of its proximity to Cougar Creek, a small stream used to designate the dam site on preliminary surveys. At the time the rockfill dam was constructed it was the largest in Oregon. This reservoir is one of 13 multi-purpose water projects built and operated by the Corps in the Willamette Valley. Operation is primarily for flood control and hydroelectric power generation. Recreational use is, of course, important and the lake is used all year, although maximum use occurs during the early summer months. Boating and fishing pressure is heavy; the lake contains coho salmon, rainbow, cutthroat and Dolly Varden trout. Overnight camping is available at three Forest Service parks around the lake. Public use is probably less than might otherwise be the case because the steep slopes that surround the lake leave little flat land adjacent to the water. Also, as with any flood control reservoir, the late summer draw-down exposes steep mud banks which further restrict access.
The drainage basin is entirely within the Willamette National Forest and is an area of rugged topography and diverse forest types, typically Douglas fir and western hemlock. The shoreline is also entirely within federal ownership. Bank stabilization at Cougar Lake has been a concern for years and has been partially improved by continued application of fertilizer to the above-water areas to encourage vegetation growth. In addition, the Forest Service and Soil Conservation Service have worked together to establish vegetative cover within the drawn-down portion of the lake.
Major ion chemistry in Cougar Lake is typical of other Willamette Valley reservoirs. Sodium and chloride concentrations, alkalinity and conductivity are all fairly low, as are phosphorus and chlorophyl concentrations. Very few, if any, macrophytes have been observed in this deep lake. Water transparency is high relative to other water quality characteristics (Secchi disk depth = 25.3 feet; 7.7 meters), indicating lower trophic conditions. However, phytoplankton species are more typical of a higher trophic state. Overall, Cougar Lake is classified as mesotrophic.