Trail Bridge Reservoir (Linn)
Reachcode: 17090004007106 | Area: 55.0 acres | Shoreline: 3.0 mi | View on Interactive Map
(From Atlas of Oregon Lakes, Johnson et al. 1985) Trail Bridge Reservoir, adjacent to U.S. Highway 126 along the Upper McKenzie River, was built in 1963 by the Eugene Water and Electric Board as one of three area reservoirs in the Carmen-Smith Hydroelectric Development. The entire system supplies 113,000 kilowatts of peak power to the Eugene area, 70 miles to the west. The unique feature of power production at Trail Bridge Reservoir is the diversion of part of the McKenzie River through a tunnel into Smith Reservoir, and then back into the McKenzie River at Trail Bridge through a power tunnel and penstock. A small power plant is also located at the 98-foot high rockfill dam that forms the reservoir.
The drainage basin of the reservoir straddles the geologic border between the older, deeply eroded western Cascades, and the younger High Cascades, which are characterized by relatively fresh volcanic terrain. The steep, forested slopes of the Smith River sub-basin contrast sharply with the relatively young, unvegetated lava block fields in the northwest region of the basin. Recreation was a planned feature of Trail Bridge Reservoir, and the Willamette National Forest operates a 33-unit campground on the north shore. Rainbow trout are stocked annually, and the Eugene Water and Electric Board has cooperated with state and federal agencies in developing an artificial spawning facility for chinook salmon immediately downstream. A 10 mph speed limit for boats is in effect on the reservoir.
The major ion chemistry, alkalinity and conductivity of the water are typical of reservoirs in the Willamette drainage basins. Phosphorus concentrations are somewhat above average, but chlorophyl concentrations and water transparency indicate that the reservoir is oligotrophic.