What is Stormwater?
Stormwater refers to the rain and snow that falls to the ground. Once the water hits the ground it can either be absorbed into the ground, infiltrate, or it can run off surfaces. The path stormwater takes is determined by the type of material it lands on. When stormwater lands on natural ground cover like grass, the water can infiltrate into the ground. This type of surface is called a permeable surface because it allows liquids, such as water, to pass through it. An impermeable surface on the other hand, refers to a surface that don't allow liquid to pass through it. These surfaces are things like roads, parking lots, and roofs. As cities grow and expand, more and more of the ground becomes impervious surface. These impervious surfaces cause an increase in stormwater as less and less water is able to infiltrate into the ground.
Why be concerned about stormwater?
The excess water that runs off of impervious surfaces can create big problems. In general the issues surrounding stormwater fall into two major categories: water quantity and water quality.
Water quantity deals with how much water there is. Due to less pervious surfaces, more water is running off of streets and buildings. The City manages this extra water to protect properties and minimize flooding. One way this can be done is by piping water into storm drains that can carry the water into nearby streams and rivers.
The other aspect of stormwater that the City manages is water quality, how healthy and clean the stormwater is. Stormwater can easily pick up pollutants, such as metals, bacteria, and sediment, as it flows across impervious surfaces. These pollutants can harm not only our local aquatic environments, but also human health! The City of Tumwater gets its drinking water from groundwater, and pollutants that get picked up from the surface can threaten our drinking water supply!
The Stormwater Utility protects water quality, reduces harm to aquatic habitats, and minimizes flooding in the City. The City has outlined a comprehensive approach to the overall management of stormwater in the 2002 Comprehensive Stormwater Implementation Plan. This plan focuses on long-term stormwater goals while emphasizing prevention, community participation, and resource conservation.
Contact Water Resources staff at (360) 754-4140 or visit us at Tumwater City Hall, Public Works counter (basement), 555 Israel Road SW, Tumwater, WA (map).