Overview and History

The Capitol Lake – Deschutes Estuary includes the 260-acre Capitol Lake Basin, located on the Washington State Capitol Campus, in Olympia, Washington. This waterbody is an important recreational resource and valued amenity; however, it suffers from numerous environmental issues.

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Water Quality Standard Violations

Capitol Lake is currently violating water quality standards because of high levels of phosphorus, which cause algae blooms that deplete dissolved oxygen in Capitol Lake and the adjacent Budd Inlet, using up oxygen essential for fish and other aquatic life.

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Sediment Management Issues

Every year more than 35,000 cubic yards of sediment from the Deschutes River is deposited within the lake basins, resulting in increasingly shallow conditions. Today, the lake is about 21 percent smaller and it holds roughly 60 percent less water than it did in 1951.

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Presence of Invasive Species

Fish and wildlife habitat are impacted due to the presence of several invasive and nuisance species including the New Zealand mudsnail, purple loosestrife, Eurasian watermilfoil, nutria, and Canada geese. These species out compete and negatively impact native populations.

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Restricted Active Community Use

Over the years, high bacterial levels and the presence of invasive species have resulted in impacts to the recreational use of Capitol Lake. The presence of New Zealand mudsnails resulted in official closure to all active uses in 2009 and active use of the waterbody continues to be restricted today.


In 2016, stakeholders, in collaboration with Washington State Department of Enterprise Services (Enterprise Services), identified common goals that should be satisfied by any long-term management alternative.

In 2018, Enterprise Services was directed by the State Legislature to develop an Environmental Impact Statement (EIS) that evaluates alternatives for long-term management. Enterprise Services is now preparing an EIS to document the potential environmental impacts of various alternatives and determine how these alternatives meet the long-term management objectives.

The EIS will evaluate and identify a preferred environmentally and economically sustainable long-term management alternative for the Capitol Lake – Deschutes Estuary Project.

Where is the project located?

Capitol Lake – Deschutes Estuary includes the 260-acre Capitol Lake Basin, located on the Washington State Capitol Campus. The Capitol Lake Basin is located within the area extending from the south end at Tumwater Falls in the City of Tumwater to the north end at the Fifth Avenue Dam in the City of Olympia.

Map of Capitol Lake/Lower Deschutes Watershed

Capitol Lake – Deschutes Estuary map, click to enlarge

While the limits of the Capitol Lake – Deschutes Estuary Long-Term Management Project are focused on the area that Enterprise Services manages (the Capitol Lake Basin), it is recognized that the interconnectedness of the system requires coordinated agency efforts.

What alternatives are being evaluated?

Enterprise Services has identified a minimum of four primary alternatives to be evaluated in the EIS. The fundamental concepts for these four primary alternatives are summarized below. Several options and concepts, or variations of the primary alternatives have also been proposed.

Alternatives Screening and Revisions

A screening process will be used to identify the range of alternatives that move forward for detailed technical review in the EIS. Options and concepts will be screened for their ability to meet project objectives and their feasibility. Enterprise Services acknowledges that these alternatives may be modified, changed, or replaced during the EIS scoping process or preparation of the EIS.