The Cowlitz River is a river in the state of Washington in the United States, a tributary of the

Columbia River The Columbia River (Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, C ...

. Its tributaries drain a large region including the slopes of

Mount Rainier Mount Rainier (), indigenously known as Tahoma, Tacoma, Tacobet, or təqʷubəʔ, is a large active stratovolcano in the Cascade Range of the Pacific Northwest, located in Mount Rainier National Park about south-southeast of Seattle. With a s ...

, Mount Adams, and Mount St. Helens. The Cowlitz has a drainage basin, located between 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, ...

in eastern Lewis County, Washington and the cities of Kelso and Longview. The river is roughly long, not counting tributaries. Major tributaries of the Cowlitz River include the Cispus River and the Toutle River, which was overtaken by volcanic mudflows (

lahar A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley. Lahars are extreme ...

s) during the May 1980 eruption of Mount St. Helens. When the smelt spawn in the Cowlitz River, the gulls go into a feeding frenzy that lasts for weeks. Kelso, Washington is known as the "Smelt Capital of the World".

Dams

The Cowlitz River has three major hydroelectric dams, with several small-scale hydropower and sediment retention structures within the Cowlitz Basin. The Cowlitz Falls Project is a 70 megawatt

hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...

dam built in the early 1990s and completed in 1994. The dam is high and wide. The Cowlitz Falls Project produces on average 260

GWh A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy: one kilowatt of power for one hour. In terms of SI derived units with special names, it equals 3.6 megajoules (MJ). Kilowatt-hours are a common bil ...

annually for Lewis County PUD. Its reservoir,

Lake Scanewa Cowlitz Falls Dam is a 70 megawatt hydroelectric dam in Lewis County, Washington. It was constructed in the early 1990s and completed in 1994. The dam is high and wide. Its reservoir, Lake Scanewa, is located at the confluence of the Cowlitz Riv ...

, is located at the confluence of the Cowlitz and Cispus Rivers downstream of

Randle Randle, as a surname or a given name, may refer to: Surname: * Betsy Randle (born 1955), American actress * Bill Randle (1923–2004), American disc jockey, lawyer and university professor * Brian Randle (born 1985), American NBA coach and basketba ...

. Mossyrock Dam began generating power for

Tacoma City Light Tacoma Power is a public utility providing electrical power to Tacoma, Washington and the surrounding areas. Tacoma Power serves the cities of Tacoma, University Place, Fircrest, and Fife, and also provides service to parts of Steilacoom, La ...

in 1968. It rises from bedrock and created the long

Riffe Lake Riffe Lake is a long reservoir on the Cowlitz River in the U.S. state of Washington. It was created in with the construction of Mossyrock Dam by Tacoma City Light (now Tacoma Power). Originally named Mossyrock Lake, then later as Davisson Lake a ...

(previously Davisson Reservoir). It is the highest dam in the Pacific Northwest.Cowlitz River Project
, Tacoma Power The dam is named for the nearby city of Mossyrock, and the lake for the town of Riffe, which, along with Kosmos, was destroyed by the flooding of the Cowlitz River valley above the dam. The Mayfield Dam is long and high. An tunnel connects the reservoir to the powerhouse. The dam began producing electricity in 1963. Mayfield Lake offers many recreational opportunities: there are several county and state parks and the lake is below the Mossyrock Dam. The modulated inflow from the Mossyrock Dam allows Mayfield Lake to maintain a water level that rarely fluctuates more than a few feet. It is located several miles downstream of Mossyrock. Packwood Lake was dammed in 1964 by the Washington Public Power Supply System (now called Energy Northwest). The dam holds back the lake (previously held back by an ancient landslide), redirecting streamflow to a 27 megawatt hydroelectric generator in the Cowlitz River valley floor 2,000 feet (600 m) below just outside the town of Packwood. When designing and building the dam, care was taken so as not to affect the abundant wildlife of the lake and surrounding area: the dam raised the water level by only a few feet. A serious side effect of the Mount St. Helens 1980 eruption has been the downstream movement of enormous amounts of sediment through the North Fork Toutle River. After the eruption, river-borne sediment increased over five thousand-fold, making the Toutle River one of the most sediment-laden rivers in the world. The

Toutle River Sediment Retention Structure The Sediment Retention Structure is an earthen dam, long and high, on the North Fork Toutle River in the U.S. state of Washington. Completed by the United States Army Corps of Engineers in 1989, it is meant to prevent sediment from the 1980 erupt ...

was constructed to trap this sediment before it was carried farther downstream, where it could clog the river channel, exacerbate floods along the lower Toutle and Cowlitz Rivers, and fill the

shipping channel, which still requires periodic dredging. An overflow channel has been added to divert

s around the dam.

Bridges

Numerous road and rail bridges span the Cowlitz. Just upstream from its mouth at the Columbia river, a railroad bridge connecting the Port of Longview to the BNSF rail line crosses the Cowlitz, with a road bridge for SR 432 (Tennant Way) beside. Further upstream are the Allen St. and Cowlitz Way bridges, connecting West Kelso with the rest of Kelso. Just north of Kelso, a railroad bridge provides crossing for the Columbia & Cowlitz Railroad. Connecting SR 411 to Interstate-5 is the Lexington bridge, a two-lane bridge between the large unincorporated community of Lexington to Exit 42 on the east side of the bank. At

Castle Rock Castle Rock may refer to: Geography Islands * Castle Rock (Alaskan Island), an island off the coast of the U.S. state of Alaska * Castle Rock, Hong Kong (螺洲白排), an island of Hong Kong, part of the Po Toi Islands * Castle Rock (Massachusett ...

, the A St. bridge provides access from downtown to the school and residential areas across the river. A few miles north, after the Toutle River split, the BNSF line crosses the river. Across the Lewis/

Cowlitz County Cowlitz County is a county located in the U.S. state of Washington. As of the 2020 census, its population was 110,730. The county seat is Kelso, and its largest city is Longview. The county was formed in April 1854. Its name derives from the ...

line, between the towns of Vader and Toledo, Washington,

I-5 Interstate 5 (I-5) is the main north–south Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels through the states of Californi ...

crosses the river. At Toledo, SR-505 crosses the river as well. Where

Highway 12 Route 12 or Highway 12 can refer to: For a list of roads named A12, see A12 roads. International * Asian Highway 12 * European route E12 * European route E012 Argentina * National Route 12 Australia NSW * Western Sydney Airport Motorway ( ...

crosses Mayfield Lake, just west of Mossyrock, causeways were built out to the middle of the lake, where a short bridge section connects the two sides. A small bridge provides a crossing for SR 122 at the head of Mayfield Lake. Just east of Mossyrock, the Cowlitz River Bridge on Highway 12 was the largest concrete arch bridge in North America until 1971 at . At the head of Riffe Lake, the 27 Road provides access to the forestland south of the Cowlitz from Morton and Glenoma to the north. At

, SR 131 crosses the Cowlitz to provide access to the Cispus basin and the northern areas of the Mount St. Helens National Volcanic Monument. Between Randle and Packwood, Highway 12 crosses the Cowlitz at the Cora bridge. At Packwood, Skate Creek Road spans the river, providing access to the Gifford Pinchot National Forest and

Tatoosh Wilderness The Tatoosh Wilderness is a designated wilderness in the Gifford Pinchot National Forest in Washington in the Pacific Northwest region of the United States. The wilderness protects managed by the U.S. Forest Service. It was officially designate ...

, as well as connecting the downtown and residential areas of Packwood. Upstream from Packwood, the Cowlitz splits into the Muddy and Clear Forks, with several Forest Service and Park Service roads crossing each.

Other river structures

When the Cowlitz Salmon Hatchery began operation in 1968, it was the largest of its kind in the world. Currently, it produces nearly 13 million fish each year. Adjacent is the barrier dam, which diverts spawning and upriver migrating fish to a separating station where fish are sorted by species. Some of the fish are used by the hatchery while others are transported upstream to continue migration. The Bonneville Power Administration, in cooperation with the Lewis County PUD, state and federal agencies and Tacoma Power, constructed a downstream anadromous fish collection facility as part of the Cowlitz Falls Project. The fish facility, along with the Cowlitz River Salmon Hatchery's diversion dam below Mayfield Lake, has permitted the reintroduction of salmon and steelhead in the upper Cowlitz River basin for the first time since the construction of the Mossyrock and Mayfield dams in the 1960s.

Main tributaries

* Ohanapecosh River * Lake Creek * Johnson Creek * Cispus River * Tilton River * Sulphur Creek * Winston Creek * Lacamas Creek * Olequa Creek * Toutle River *

Coweeman River The Coweeman River is a tributary of the Cowlitz River, in the South West corner of the U.S. state of Washington. Its name comes from the Cowlitz word ko-wee-na, meaning "short one", referring to a short Indian who once lived along the river. Cour ...

Recreation

The Cowliz River's two hatcheries provide an exceptional sportfishing opportunity for recreational anglers in Washington and Oregon. The river consistently ranks as one of the states top ten steelhead and salmon producers.

References

External links

USGS Cowlitz River Basin map

energy-northwest.com

The Army Corps of Engineers' Mt. St. Helens Sediment Retention Structure
{{authority control Rivers of Washington (state) Tributaries of the Columbia River Rivers of Cowlitz County, Washington Rivers of Lewis County, Washington Gifford Pinchot National Forest Mount Rainier