Capitol Lake: The Dam That Replaced an Estuary

Stand at the foot of the Washington State Capitol grounds and look south, and you see a lake. A long, narrow body of freshwater, reflecting the dome above it. The view is deliberate. The lake was built to be looked at from exactly this angle.

Before nineteen fifty-one, there was no lake here. There was an estuary. The Deschutes River met the saltwater of Budd Inlet over broad tidal flats where the Squaxin Island people had gathered shellfish for millennia. The tides moved in and out twice a day. The mixing zone was productive and biologically complex, the kind of environment where nutrients accumulate and life concentrates.

Between nineteen forty-nine and nineteen fifty-one, a dam was constructed across the tidal inlet at Fifth Avenue. The dam blocked the tidal exchange. The estuary became a freshwater lake. The view of the capitol from the water, the planners decided, would be improved.

What followed was slow and largely invisible. Without tidal flushing, sediment from the Deschutes River accumulated in the basin, building up thickly in some areas over the following decades. Aquatic invasive species moved in. Water quality declined. The swimming beach at Capitol Lake was closed in the nineteen eighties because of bacterial contamination. In two thousand nine, the presence of the invasive New Zealand mudsnail led to closure of the lake to all public uses.

That same year, after twelve years of scientific study, the Capitol Lake management committee reached a consensus recommendation: restore the estuary. Remove the dam. The Squaxin Island Tribe had been saying the same thing for years. The dam is still there. The estuary is still not.