Water Quality photo identifier

Land use and Nonpoint Pollution

Land Use

Nonpoint pollutants are introduced into water through runoff. Rainfall and snow melt wash pollutants from the land into rivers, streams, lakes, oceans, and underground aquifers. Different land uses can produce the same kinds of pollution. To manage nonpoint pollution, we must focus on land use activities.


We’ve made progress in reducing various types of water pollution, but a growing body of evidence shows that nonpoint pollution, including runoff from agricultural lands, also threatens our receiving waters and our underground water supplies.


Increased sedimentation and water temperature are historically the greatest problems associated with forestry.

Urban Areas

Clearing for buildings, parking lots, and landscaped areas occurs at a rapid rate in Washington State. Runoff these areas may contain high concentrations of heavy metals, lawn and garden chemicals, bacteria, silt, petroleum products, and nutrients which enters streams. The volume of water from runoff can also dramatically increase stream volume and peak flows, reducing summer flows.

Working in the Water

People have modified many stream systems in Washington, with considerable effect on the landscape. Dams, tide gates, culverts, and other modifications benefit people and the economy, but at the expense of aquatic ecosystems and fish habitat.

Land Use Changes in Washington State

Nonpoint Land Use Chart.  Author unknown.


Last updated July 2012