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Black Lake Basin

Basin OverviewBlack Lake Photo

The Black Lake Basin includes almost 5,000 acres that drain into one of the largest lakes in Thurston County. Historically, Black Lake was the headwaters of the Black River system, but since the excavation of the Black Lake Ditch in 1922, it has been linked hydrologically to Percival Creek and drains into Puget Sound via Budd Inlet. The basin is moderately impacted by development, with less than 10 percent of covered by impervious surfaces (e.g., roads and parking lots) and reduced tree canopy. Algal blooms are a recurring and increasing problem in Black Lake. Black Lake Ditch, which drains the lake at its northern end, violates fecal coliform and dissolved oxygen standards.

In the coming decades, the Black Lake Basin, which includes northwestern Tumwater and its unincorporated urban growth area, will see new commercial and residential development under current zoning. This growth could increase the amount of impervious surfaces and stormwater runoff, exacerbating water quality issues. The aim of this project is to identify policies that can be put in place now to preserve the health of the basin into the future.

A final report with recommendations was completed in June 2015.

Public Outreach

A survey was sent out to landowners in the summer of 2013 to gather initial feedback. On April 9, 2014, Thurston County and TRPC hosted a public workshop on water resources for Black Lake Basin (and nearby McLane Creek). The following information was presented at that meeting:

The project team used information from a modeling study and community outreach to draft options for how the area could be managed in the future. We presented the following information at a second workshop on October 30, 2014.


This project has been funded wholly or in part by the United States Environmental Protection Agency under assistance agreement (PO -00J12401-0) to Thurston County. The contents of this website do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.


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