|Location||Olympia / Tumwater, Washington, United States|
|Type||artificial lake, Formerly wetlands and estuary|
|Primary inflows||Deschutes River|
|Basin countries||United States|
|Max. length||3 km|
|Surface area||260 acres (1.1 km2)|
Capitol Lake is a 3 kilometer long, 260-acre (1.1 km2) artificial lake at the mouth of Deschutes River in Tumwater/Olympia, Washington. The Olympia Brewery sits on Capitol Lake in Tumwater, just downstream from where the Tumwater Falls meet the lake. The Washington State Department of General Administration manages the lake, as part of The Washington State Capitol Campus.
Prior to American settlement, the tidal basin at the southern tip of Budd Inlet was a productive shellfish gathering area for native peoples. After settlement in the mid-19th century, the basin received much of the wastewater and other effluent outflow from "uptown" Olympia. In the 1890s the Northern Pacific Railroad located a station and switching yard on the eastern shore of the basin.
The first proposal for creating Capitol Lake came when Leopold Schmidt of the Olympia Brewing Company proposed in 1895 to " mak(e) a fresh water lake of it by building a dam and locks near the Westside (Olympia) bridge." 
In 1911 the State Capitol Commission held a nationwide competition for the design of the State Capitol Campus. The winning architects, Wilder and White, submitted a revolutionary City Beautiful Movement and American Renaissance plan which included creating a body of water to reflect the Capitol Group of buildings on the bluff by installing a tidelock at the mouth of the Deschutes River.
A more limited lake was also part of the original landscape design by John Olmsted to reflect the Washington State Capitol building on Puget Sound. The lake as envisioned by Olmsted would have been created with a north to south running berm, as opposed to an east to west running dam.
In 1915, the State Capitol Commission rejected a plan by former Olympia Mayor and state legislator P.H. Carlyon to replace Olympia's bridge to the westside with a dam and locks. That plan would have created a lake very much like the present Capitol Lake. Because of opposition from upriver Tumwater businesses, such as the Olympia Brewing Company and the Olympia Power and Light Company, that plan was not approved.
The Capitol Group of buildings was constructed over several years from 1913 to 1940, and the State Capitol Committee then turned to the task of creating the Wilder and White reflecting Capitol Lake. In 1937 the state began purchasing the privately owned tidelands around the Capitol Campus. In 1941, opposition from Tumwater was finally overcome during a special town meeting. In 1947, due in large part by intense lobbying by Thurston County legislators, the state legislature approved funding for the construction of the dam in order to create Capitol Lake.
A shantytown known as “Little Hollywood” developed along the shores of the Deschutes River, at the foot of the Capitol Campus. The people living in the shanties dumped raw human waste and trash directly into the Deschutes River. This became an eyesore (July 7, 1948, The Daily Olympian) and probably a health hazard. Damming the Deschutes River destroyed the estuary, but also prevented the urban blight of the shantytown from recurring.History of Capitol Lake, by WA State Dept. of Enterprise Services 
￼￼￼￼Capitol Lake was finally created in 1951 when the dam was completed consistent with the Wilder and White plan. This allowed for the retention of the outflow from the Deschutes River to cover the tide flats. Capitol Lake is a visual and recreational amenity and an appropriate setting for the acropolis of the Capitol Group which the Lake handsomely supports and reflects. Johnson, Norman J., "Washington's Audacious State Capitol and Its Builders", Seattle and London, University of Washington Press (1988).
In the 1990s and 2000s the North Capitol Campus Heritage Park was created with the Arc of Statehood from the Western Washington Inlet to the Eastern Washington Butte along the eastern edge of Capitol Lake and the North Campus trail and Law Enforcement Memorial with views across Capitol Lake to the borrowed landscapes of Puget Sound and the Olympic Mountains.
The February, 2001 Nisqually Earthquake did considerable damage to Deschutes Parkway on the west side of the lake. Capital Lakefair, centered on the lake, is held annually in July. The trail around the lake is 1.5 miles long.
Recommendation for Estuary Restoration
In 2009, after 12 years of intensive and independently verified scientific study, the Capitol Lake Adaptive Management Plan Steering Committee reached a consensus recommendation to remove the 5th Ave. dam and restore Deschutes Estuary as the most cost-effective and ecology sound long term plan for this watershed. As described on page 6 of the report, CLAMP made the recommendation to for Deschutes Estuary restoration stating:
"The Department of Fish and Wildlife, Department of Ecology, Department of Natural Resources, Squaxin Island Tribe, and a majority of the Thurston County Commissioners are forwarding their recommendation to return the Capitol Lake Basin to an estuary."
Because of a high rate of siltation, the lake has been dredged periodically in the past to keep it from filling in. After a twenty-five year hiatus, in 2011 the State Legislature appropriated $200,000 in order to seek permits to reimplement maintenance dredging in order to retain and improve Capitol Lake as part of the historic Wilder and White design of the State Capitol Campus during its centennial year.
In 2009, the New Zealand mud snail, an invasive species the size of a grain of rice, was discovered in Capital Lake. The lake has been closed to all public use, including boating and other recreation, since 2009. A heavy cold snap in 2013, combined with a drawdown in water level in preparation, was roughly estimated to have killed 40–60% of the mudsnail population.
Controversy surrounds Capitol Lake because it replaced an estuary. Because of a high rate of siltation, the lake was dredged periodically in the past to keep it from filling in, a classic case of eutrophication. Additionally, there is a milfoil infestation and poor water quality (it is closed to swimmers due to unsafe levels of E. coli).
In June 2012, the Washington State Department of Ecology released a report titled: Deschutes River, Capitol Lake, and Budd Inlet Temperature, Fecal Coliform Bacteria, Dissolved Oxygen, pH, and Fine Sediment Total Maximum Daily Load Technical Report - Water Quality Study Findings by scientists; Mindy Roberts, Anise Ahmed, Greg Pelletier, and David Osterberg This study provided the following information in a question and answer format.
Q) Is there a problem with Capitol Lake?
A) Capitol Lake is a popular destination in Olympia because of its beauty and accessible trails. Large numbers of birds, salmon and bats use the lake, offering a unique opportunity for watching wildlife in an urban setting. The hillsides surrounding the area offer magnificent views of the lake, Puget Sound, the Olympic Mountains and Mount Rainier.
But Capitol Lake has some problems.
Every year more than 35,000 cubic yards of sediment comes down the Deschutes River and settles into the lake. That’s enough soil to cover a city block to a depth of three feet. Today, the lake is about 21 percent smaller and it holds roughly 60 percent less water than it did in 1951. Capitol Lake is turning into a marsh.
A shallow lake heats quickly in the summer. High water temperatures can stress fish and other aquatic species. Warm water also encourages the growth of aquatic weeds.
Capitol Lake does not meet water quality standards because of high levels of phosphorus, which causes algae blooms. When algae and weeds die in late summer, some of it washes out into Budd Inlet where it decomposes, using up oxygen essential for fish and other aquatic life.
The lake also has high levels of fecal coliform bacteria, which can pose a health risk if ingested. The bacterium is washed into the lake through the stormwater system.
Non-native weeds, such as Eurasian milfoil, are found in the lake and along the shoreline. These weeds crowd out native vegetation, reducing fish and wildlife habitat. Invasive species, like the New Zealand Mudsnail, are also found in Capitol Lake and can dominate lakebed habitat by outcompeting native aquatic snails and insects that other species depend on for food.
Before Capitol Lake was created, this area was an estuary, where freshwater from the Deschutes River mixed with the saltwater of Budd Inlet, part of Puget Sound. At the time the lake was created, the existing estuary had water quality problems and had been greatly modified by urbanization.
The Department of General Administration, other state and local agencies, and the Squaxin Island Tribe participated in a study entitled "The Capitol Lake Adaptive Management Plan" or "CLAMP" to determine the future of the lake. For 10 Years the CLAMP met, discussing alternative solutions to the issues of the lake. The CLAMP was dissolved due to budget issues, but not before recommending that the best solution to the lake problems is to remove the dam and restore the estuary.
In a multiyear comprehensive scientific study, the Washington State Department of Ecology determined that Capitol Lake reservoir is harmful to the water quality of Budd Inlet in South Puget Sound. This is an excerpt from that study: "Portions of the Deschutes River, Capitol Lake, and Budd Inlet do not meet the water quality standards and are on the Clean Water Act Section 303(d) list for one or more of the following parameters: fecal coliform bacteria, temperature, dissolved oxygen (DO), pH, or fine sediment. This report summarizes the technical basis for a water cleanup plan (Total Maximum Daily Load study), which was conducted to determine the targets that enable water bodies to meet standards."
"The combined effects of current nonpoint and point sources exceed the loading capacity of both Budd Inlet and Capitol Lake for nutrients with the lake in place. With Capitol Lake in place, more of Budd Inlet and Capitol Lake would violate standards for DO (dissolved oxygen) under critical conditions than with a restored Deschutes estuary."
If the lake were to revert to an estuary, a smaller portion of Budd Inlet would violate standards for DO, and the geographic area that is currently Capitol Lake would meet marine water quality standards for DO under all nutrient loading alternatives. Load reductions are needed under either alternative and will be developed in the Water Quality Improvement Report.WA State Dept of Ecology Study shows Capitol Lake harms water Quality in Budd Inlet
There are two groups in Olympia that are actively involved in public education on the lake. One group is known as CLIPA, "Capital Lake Improvement and Protection Association," while the other group, known as DERT, or "Deschutes Estuary Restoration Team," supports dam removal and restoration of the free flowing waters of the Deschutes.
- History of the Olympia Brewing Company
- Original Capitol Planners Called For Free Flowing Deschutes River, Squaxin Island Tribe
- The myth of connection between Wilder and White and Capitol Lake, Olympia Historical Society
- Capitol Lake Timeline, Save Capitol Lake
- The myth of connection between Wilder and White and Capitol Lake, Olympia Historical Society
- Photos of earthquake damage from UW
- Lake Fair official website.
- Capitol Lake website.
- Dodge, John (19 October 2010). "Snail seclusion successful". The Olympian.
- Shannon, Brad (4 December 2013). "Freeze could help kill Capitol Lake's mudsnail population". The News Tribune.
- Shannon, Brad (26 December 2013). "Cold estimated to have killed half of snails in Capitol Lake". The Olympian.
- GA director message about suspension of CLAMP committee