Riffe Lake is a long
reservoir
A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation.
Reservoirs are created by controlling a watercourse that drains an existing body of wa ...
on the
Cowlitz River
The Cowlitz River is a river in the state of Washington in the United States, a tributary of the Columbia River. Its tributaries drain a large region including the slopes of Mount Rainier, Mount Adams, and Mount St. Helens.
The Cowlitz has a ...
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 so ...
of
Washington
Washington most commonly refers to:
* George Washington (1732–1799), the first president of the United States
* Washington (state), a state in the Pacific Northwest of the United States
* Washington, D.C., the capital of the United States
** A ...
. The lake was created by the construction of
Mossyrock Dam
Mossyrock Dam is a concrete arch-gravity dam on the Cowlitz River near Mossyrock in Lewis County, Washington, United States. The reservoir created by the dam is called Riffe Lake. The primary purpose of the dam is hydroelectric production wh ...
, the tallest dam in the state, in 1968 by Tacoma City Light (now
Tacoma Power
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, L ...
).
Riffe Lake includes 6
islands
This is a list of the lists of islands in the world grouped by country, by continent, by body of water, and by other classifications. For rank-order lists, see the #Other lists of islands, other lists of islands below.
Lists of islands by count ...
, 3 of which being incredibly small, sandy
islets
An islet ( ) is generally a small island. Definitions vary, and are not precise, but some suggest that an islet is a very small, often unnamed, island with little or no vegetation to support human habitation. It may be made of rock, sand and ...
, and one being a
tidal island
A tidal island is a raised area of land within a waterbody, which is connected to the larger mainland by a natural isthmus or man-made causeway that is exposed at low tide and submerged at high tide, causing the land to switch between being ...
. None of them have names.
History
The reservoir was formed behind Mossyrock Dam in the late 1960s and submerged the communities of
Kosmos
Cosmos generally refers to an orderly or harmonious system.
Cosmos or Kosmos may also refer to:
Space
* ''Cosmos 1'', a privately funded solar sail spacecraft project
* Cosmic Evolution Survey (COSMOS), a Hubble Space Telescope Treasury Project
...
,
Nesika, and Riffe; residents of the area were relocated due to the planned inundation.
It was originally called Mossyrock Lake, then later named Davisson Lake in 1962 after Ira Davisson, a utilities commissioner in Tacoma. The name was approved by the
Tacoma Utilities Board and later the
Federal Power Commission
The Federal Power Commission (FPC) was an independent commission of the United States government, originally organized on June 23, 1930, with five members nominated by the president and confirmed by the Senate. The FPC was originally created in ...
.
The 1968
state highway
A state highway, state road, or state route (and the equivalent provincial highway, provincial road, or provincial route) is usually a road that is either Route number, numbered or maintained by a sub-national state or province. A road numbered ...
map published by the
Washington State Department of Highways named it "Riffe Lake" for the inundated community instead of Davisson Lake, which was not officially recorded by the
U.S. Board on Geographic Names. The name was officially changed to Riffe Lake in 1976 after Lewis County residents petitioned the state's Board of Geographical Names to honor a more local figure.
The change was approved by the U.S. Board on Geographic Names in August of that year.
In 2017, Tacoma Power lowered the maximum water level of the lake by due to concerns that the piers on Mossyrock Dam could fail during a major seismic event and cause catastrophic flooding.
Ecology and environment
Located on the eastern shore of the lake is the Kosmos Unit, a part of the Cowlitz Wildlife Area. Also known as Kosmos Flat, the site contains a mix of habitats, such as meadow,
riparian
A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...
, and wetland, and is split by Rainey Creek. Parts of the meadow are flooded during peak water levels. The unit contains a small hardwood forest and is known for abundant wildlife, especially various species of birds including pheasants, ospreys, and raptors. Additional sites for birdwatching include Goat Creek Flats and Landers Creek Flats.
Recreation
The lake accommodates two parks, Mossyrock Park and
Taidnapam Park. Due to the decrease in water levels, the boat launches at both recreation areas have been closed periodically since 2017 and are only reopened when water levels are increased. During this time, the parks underwent recreation improvements with proposals to extend the launches for more consistent accessibility.
The Gary Stamper Memorial Overlook, located on the northern shore of Riffe Lake off
U.S. Route 12
U.S. Route 12 or U.S. Highway 12 (US 12) is an east–west United States Numbered Highway, running from Aberdeen, Washington, to Detroit, Michigan, for almost . The highway has mostly been superseded by Interstate 90 (I-90 ...
, was opened and dedicated in June 2025. Named in honor of a long-serving community volunteer and Lewis County commissioner who was born in the area before it was flooded, the overlook contains a memorial plaque and an interpretive panel.
The lake contains species of fish including
rainbow
A rainbow is an optical phenomenon caused by refraction, internal reflection and dispersion of light in water droplets resulting in a continuous spectrum of light appearing in the sky. The rainbow takes the form of a multicoloured circular ...
and
brown trout
The brown trout (''Salmo trutta'') is a species of salmonid ray-finned fish and the most widely distributed species of the genus ''Salmo'', endemic to most of Europe, West Asia and parts of North Africa, and has been widely introduced globally ...
, landlocked coho, bass both large mouth and small mouth, bluegill,
crappie
Crappies () are two species of North American freshwater fish of the genus ''Pomoxis'' in the family Centrarchidae (sunfishes). Both species of crappies are popular game fish among recreational anglers.
Etymology
The genus name ''Pomoxi ...
, and perch.
See also
*
List of lakes in Washington
This is a list of natural lakes and reservoirs located fully or partially in the U.S. state of Washington. Natural lakes that have been altered with a dam, such as Lake Chelan, are included as lakes, not reservoirs. Swimming, fishing, and/or boa ...
References
Lakes of Lewis County, Washington
Reservoirs in Washington (state)
Buildings and structures in Lewis County, Washington
Protected areas of Lewis County, Washington
Tacoma Public Utilities
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