When rain falls on forest and fields, most of it soaks into the ground gradually. Some water flows overland to streams, lakes or wetlands; most flows slowly underground to feed streams and lakes as groundwater.

However, when urban and suburban development covers the land with buildings, houses and streets, the trees, shrubs, grass and topsoil are replaced by concrete and asphalt. Less rain soaks into the soil and the result is "urban runoff": water on the surface quickly runs off into storms drains, ditches or streams and then directly into our lakes and Puget Sound.

Urban runoff pollutes and floods streams. Runoff carries with it litter, oil, gas, fertilizer, pesticides and anything else that will float, dissolve or be moved along. The storm drains that carry most of this runoff usually convey it untreated into streams or lakes. As more water is forced to run off, downstream flooding becomes more frequent and more severe. Increased flooding erodes stream banks and destroys salmon spawning beds, not to mention property.

Not all of our water problems begin in urban areas. Rural activities like farming, ranching and timber harvesting also affect the quality of water in our streams, lakes and Puget Sound. But neither urban nor rural problems are insurmountable – far from it. With proper management and common sense we can all enjoy cleaner, safer water.

All of us can help stop water pollution. It’s easy to blame dirty water on industry, but a very significant portion of the problem starts right at home. The information in this website will help you find out how you can do your share to stem water pollution at its source.