Basin plans are in-depth studies that identify water-quality problems in the streams and rivers that drain to a common point, like the Puget Sound.  Plans often include recommendations for projects to resolve the worst of the problems.

• Studies involve analyzing data about the topography of the land, and the way water moves overland and through the soil.  Studies are often grant-funded by the U.S. Environmental Protection Agency, which regulates water quality throughout the U.S.
• Problems in a rainy place like Thurtson County may include flooding, poor water quality due to rainwater runoff that picks up vehicle fluids from roads and soil from exposed construction sites; and the effects of this dirty water on community drinking water aquifers, frogs, fish, shellfish and other water animals.  
• Solutions focus on specific projects that can minimize the worst of the problems that were found. Thurston's Board of County Commissioners refer to the basin plans when deciding which stormwater utility projects to approve.