Detroit Lake, Reservoir in Marion County and Linn County, United States.

Detroit Lake is a 9-mile (14 km) reservoir on the North Santiam River in the North Santiam Canyon, impounded by Detroit Dam and bordered by Oregon Route 22 near the city of Detroit. When full it has 32 miles (51 km) of shoreline and holds 455,000 acre-feet of water.

Detroit Lake was created in 1953 when the Detroit Dam was completed on the North Santiam River, part of the Willamette Valley Projects intended mainly for flood control and power generation. The reservoir flooded a road bed of the former Oregon Pacific Railroad, built by Colonel T. Egenton Hogg as a proposed transcontinental line that ran out of funding and ended at Idanha; that town kept rail service until the 1950s, when the track was removed for the Detroit and Big Cliff reservoirs.

The reservoir takes its name from the town of Detroit, which was relocated when the dam was completed in 1953. The former Oregon Pacific Railroad roadbed, built by Colonel T. Egenton Hogg, lies beneath the water; the line had ended at Idanha, southeast of the lake, until its track was removed in the 1950s for the Detroit and Big Cliff reservoirs.

Detroit Lake lies along Oregon Route 22 near the town of Detroit, 46 miles (74 km) southeast of Salem. Swimming is available at the Mongold Day-Use Area, an Oregon State Park. A winter boat ramp built in 2009 allows launching when other ramps sit on dry ground. Full pool usually runs from May 1 to September 1, when the surface rises as much as 119 feet (36 m) above the low-pool elevation of 1,450 feet (440 m).

The lake lies over the roadbed of the never-finished Oregon Pacific Railroad, built by Colonel T. Egenton Hogg as a proposed transcontinental line. Funding ran out and the track ended at Idanha; the rails were pulled up in the 1950s to make way for the Detroit and Big Cliff reservoirs.