The William L. Jess Dam and intake structure is a 327-foot-high rockfill embankment structure. Construction began in 1967 and the lake began filling in February 1977. Runoff from a drainage area of 674 square miles pools into Lost Creek Lake. The lake provides 465,000 acre-feet of total storage and has an area of 3,430 acres when full.
A regulating outlet tunnel, power penstock, and intake tower with multi-level intakes are located in the dam's right abutment; a gate-controlled concrete chute spillway is located in the left abutment. The powerhouse's generating capacity of 49,200 kilowatts comes from two 24.6-megawatt generators.
Environmental concerns prompted the Corps to construct an innovative multi-port intake tower, allowing operators regulate the temperatures of water released from the lake. Lost Creek’s intake structure combines lake water from different depths in a mixing chamber before releasing it downstream, regulating the water temperature and improving conditions for fish migration and survival in the Applegate and Rogue rivers.
The returning fish are collected just below the dam and transported to the Cole M. Rivers Fish Hatchery, located just downstream of William L. Jess Dam on the Rogue River, for spawning. Later, juveniles are released into the Applegate River to maintain the runs.
For the reservoir elevation, flow and temperature report, call 800-472-2434.