Fall Creek Dam, Fall Creek, Oregon
United States. Army. Corps of Engineers. Portland District.
General: Fall Creek Dam, completed in 1965, is a rock-fill structure located on Fall Creek, a tributary of the Middle Fork Willamette River about 20 miles southeast of Eugene, Oregon. The project is intended mainly for flood control, but has other benefits, including recreation and release of stored water for conservation and power. A vicinity map and dam and lake plans are shown in plate 1. The dam has a crest length of 5050 ft, a crown width of 24 ft, a maximum height above foundation of 205 ft, and a total fill volume of 5,180,848 cu yd. Additional pertinent data are presented in tables 1 and 2, and a general plan with typical sections is shown in plate 2. The regulating outlet works is located on the right bank of the old river channel. The intake structure was built to el 733.0. The outlet is a cut-and-cover, twin-box conduit beneath the embankment. The control gates are located in a concrete domed structure within the embankment and are connected by a passageway to the adit building at the downstream toe of the dam. The stilling basin is 35 ft deep. Maximum discharge with the reservoir at minimum pool elevation is 4790 cfs. Minimum flows are obtained by use of the fish-passing facilities discussed in paragraph 4. The outlet facilities are shown in plate 1. The spillway consists of a two-bay, gated, overflow gravity section located near the left abutment. Design discharge is 82,400 cfs at maximum pool el 834. The approach channel is 90 ft wide with concrete gravity retaining walls on each side. A 90-ft-wide paved spillway channel with counterfort walls extends downstream beyond the embankment toe. The spillway section is shown in plate 1. Fish migrating upstream are led by a short fish ladder to a holding trap. The trapped fish are then trucked upstream of the reservoir for spawning in Fall Creek. The young salmon and steelhead trout returning to sea are passed through the downstream migration facilities, which comprise three sets of fish horns at different elevations. These horns are designed to attract downstream migrating fish and to operate with a minimum loss of water from the system when storage is required. Pipes embedded above and below the regulating outlet conduits carry the migrants to a collector system at the downstream toe of the dam. The downstream migration facilities are shown in plate 1.
Earth Dam Criteria Report
U.S. Army Engineer Waterways Experiment Station
Earth dams; Flood dams and reservoirs--Oregon
Earth Dam Criteria Report;57
Approved for public release; distribution is unlimited.