The Cedar River is a

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...

. About long, it originates in the

Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...

and flows generally west and northwest, emptying into the southern end of

Lake Washington Lake Washington is a large freshwater lake adjacent to the city of Seattle. It is the largest lake in King County and the second largest natural lake in the state of Washington, after Lake Chelan. It borders the cities of Seattle on the west, ...

. Its upper

watershed Watershed is a hydrological term, which has been adopted in other fields in a more or less figurative sense. It may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins * Drainage basin, called a "watershe ...

is a protected area called the Cedar River Watershed, which provides

drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, a ...

for the greater

Seattle Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest regio ...

area. The Cedar River drains into

Puget Sound Puget Sound ( ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected ma ...

via Lake Washington and the

Lake Washington Ship Canal The Lake Washington Ship Canal, which runs through the city of Seattle, connects the fresh water body of Lake Washington with the salt water inland sea of Puget Sound. The Hiram M. Chittenden Locks accommodate the approximately difference in w ...

Course

The Cedar River originates in the

near

Abiel Peak Abiel Peak is a mountain summit located in eastern King County of Washington state. It is set 1,000 feet west of the crest of the Cascade Range, on land managed by Mount Baker-Snoqualmie National Forest. Abiel Peak is situated six miles sout ...

, Meadow Mountain, and Yakima Pass, along the King and Kittitas countyline. Several headwater streams join in the high mountains fed from glacial run-off, then the Cedar River flows generally west. It is impounded in Chester Morse Lake, a natural lake that was dammed in 1900 for use as a water storage

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

. The Rex River joins the Cedar in Chester Morse Lake, as do the two forks of the Cedar River, the north and south forks.Cedar River Watershed Environmental Overview
HistoryLink Essay. Below Chester Morse Lake, the Cedar River flows through a smaller lake called Masonry Pool. Below Masonry Pool, the Cedar River flows by two former railroad sites, Bagley Junction and Trude. The river then exits the Cedar River Watershed at Landsburg where pipelines route water to the Seattle area. Below the Cedar River Watershed area, the river flows west and north, past the cities of Maple Valley and Renton. At Renton, the Cedar River empties into the southern end of

. Its waters eventually enter

via the Lake Washington Ship Canal.

River modifications and management

The upper Cedar River

is a protected area called the Cedar River Municipal Watershed. About 90,000 acres (364 km²) in size, it is owned by the

City of Seattle Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest region of ...

. The Cedar River Watershed provides drinking water for 1.4 million people in the greater Seattle area. About two-thirds of

King County King County is located in the U.S. state of Washington. The population was 2,269,675 in the 2020 census, making it the most populous county in Washington, and the 13th-most populous in the United States. The county seat is Seattle, also the st ...

uses water from the Cedar River Watershed, over per day. The reservoirs and pipeline infrastructure is owned and operated by

Seattle Public Utilities Seattle Public Utilities (SPU) is a public utility agency of the city of Seattle, Washington, which provides water, sewer, drainage and garbage services for 1.3 million people in King County, Washington. The agency was established in 1997, co ...

. Public access is restricted and the area is managed as a

wilderness Wilderness or wildlands (usually in the plural), are natural environments on Earth that have not been significantly modified by human activity or any nonurbanized land not under extensive agricultural cultivation. The term has traditionally re ...

in order to protect water quality. Chester Morse Lake is the main storage reservoir of the Cedar River Watershed system. Pipelines route water to the Seattle area from Landsburg, at the western edge of the protected watershed area. Before 1912 the Cedar River did not empty into Lake Washington but rather into the Black River. The Black River drained the southern end of Lake Washington, flowing south then west to join the

Green River Green River may refer to: Rivers Canada * Green River (British Columbia), a tributary of the Lillooet River *Green River, a tributary of the Saint John River, also known by its French name of Rivière Verte *Green River (Ontario), a tributary of ...

. The Black-Green confluence created the

Duwamish River