Tahkenitch Lake

Tahkenitch Lake
Tahkenitch Lake from near a boat launch along U.S. Route 101
Location	Near Pacific Ocean coast in Douglas County, Oregon
Coordinates	43°48′26″N 124°09′01″W / 43.80722°N 124.15028°W / 43.80722; -124.15028Coordinates: 43°48′26″N 124°09′01″W / 43.80722°N 124.15028°W / 43.80722; -124.15028
Type	Natural, permanent, mesotrophic
Primary inflows	Fivemile and Leitel creeks
Primary outflows	Tahkenitch Creek
Catchment area	34 square miles (88 km2)
Basin countries	United States
Surface area	2,118 acres (857 ha)
Average depth	11 feet (3.4 m)
Max. depth	23 feet (7.0 m)
Water volume	18,200 acre feet (22,400,000 m3)
Residence time	2 months
Shore length1	29 miles (47 km)
Surface elevation	20 feet (6 m)
Islands	Weed, Jewitt
References
1 Shore length is not a well-defined measure.

Tahkenitch Lake (tak' ə nich), at 2,118 acres (857 ha), is one of the larger lakes along the coast of the U.S. state of Oregon. Fed by runoff from a basin of about 34 square miles (88 km²), it lies east of U.S. Route 101 in Douglas County between Florence and Reedsport. Its name comes from a Lower Umpqua (Siuslaw) placename meaning "having arms running out like a crab".

Tahkenitch Lake, like its immediate neighbor to the north, Siltcoos Lake, was formed during and after the when melting glaciers caused a rise in sea level that drowned the lower reaches of Oregon's coastal rivers. Big rivers like the Umpqua, south of Tahkenitch Lake, formed large estuaries. The mouths of smaller streams filled with sand and sediment, which eventually created dunes. Tahkenitch, Siltcoos, Woahink, and other nearby lakes formed behind these dunes. Many centuries later, the lakes remain at elevations somewhat above the lower sea of the early 21st-century. The surface of Tahkenitch is about 20 feet (6 m) above sea level.

Fed mainly by Fivemile and Leitel creeks and several smaller streams, including Elbow Lake, Mallard, and John Sims creeks, the lake is mostly shallow. The average depth is about 11 feet (3.4 m), and the maximum depth is 23 feet (7.0 m). Water leaves the lake at its west end via Tahkenitch Creek. The creek passes under Route 101 into the Oregon Dunes National Recreation Area west of the lake and meanders less than a mile into the Pacific. Of the creeks that enter the lake, only Fivemile Creek has named tributaries: Perkins, Harry, and Bell creeks.

A low dam at the west end of the lake was originally built to maintain a dependable supply of fresh water for a pulp mill in Gardiner. The lake's shape is dendritic, and several of its branches have names. Starting at the dam, the named branches in a clockwise progression around the lake are Shag Arm, Deer Arm, Big Arm, Catfish Cove, North Arm, Bear Trap Arm, Spike Arm, Fivemile Arm, Dismal Swamp, Cleves Cove, Cherry Arm, Mallard Arm, Bombard Bay, Bedolf Arm, and Bass Arms. The lake's two named islands are Weed and Jewitt, both toward the west end of the lake. Toward the east end, Leitel Marsh extends about 2 miles (3 km) beyond the lake, and Fivemile Marsh extends about twice as far.