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Stormwater runoff is rain or snow melt that does not get absorbed into the soil. Instead, it flows freely over the land, creating problems in urban and rural settings. Stormwater runoff is a naturally occurring process, but with the installation of development such as asphalt, concrete, roofs, gravel lots, and roadways, our world is becoming more impermeable. Urban development has changed how water moves in our world, increasing the speed and volume of water in small areas.

When rain or snow melt runs over impermeable surfaces, it picks up contaminants like oil, fertilizers, pesticides, pet waste, soil from bare ground, and litter such as cigarette butts and plastic. Runoff then carries these contaminants into a nearby storm drain or directly into a water body. Many people believe that water from storm drains is cleaned by a water treatment plant before entering our streams and rivers, but the reality is that water that flows into these drains travels directly into our streams and rivers, and it carries all of those pollutants with it.

Beyond surface water pollution, stormwater runoff can have additional consequences in our watershed. When rain and snow melt are prevented from soaking into the ground, they can overwhelm surface water bodies, leading to flooding and heavy erosion. Impermeable surfaces also prevent water from soaking into the ground and replenishing groundwater resources.

The Washington Department of Ecology estimates that one-third of all the polluted waters in the state are polluted by stormwater runoff. One inch of rain on a 1,200 square foot roof yields 748 gallons of stormwater runoff. One inch of rain on a one-acre parking lot yields 27,000 gallons of stormwater runoff. 

We all contribute to stormwater runoff. Simple actions such as driving your car or walking your dog can all play a role in stormwater pollution. But the good news is that there are many ways for us to help reduce the negative effects of stormwater runoff.​

To reduce the negative impacts of stormwater runoff:

  • Remove impermeable surfaces and install vegetative buffer zones to allow water to filter into the ground

  • Use a rain barrel to capture water from your roof and use it for watering your yard and garden. The water you capture will be diverted away from storm drains and used where it is needed most!

  • Install a bioretention area or rain garden on your property to filter pollutants from rain or snow melt and allow it to infiltrate into the ground. Rain gardens are shallow, landscaped depressions that retain and filter stormwater. They can include a variety of trees, shrubs, and flowering plants, making them great for pollinators, too!

  • Wash your car at commercial car washes. Car washes often recycle water, which helps to reduce runoff. If you can't use a car wash, be sure to wash your car on grass or another permeable surface using an eco-friendly soap.

  • Be sure to pick up after your pet! Pet waste carries harmful bacteria that can wash into our local waterways. And if you're interested in having a larger impact, consider volunteering in the spring or fall to help us maintain the City of Pullman pet waste stations. View our volunteer opportunities on GivePulse (external link).

  • Minimize the use of synthetic fertilizers, pesticides, and other chemicals on your property.

  • Fix vehicle fluid leaks immediately.

  • Perform regular maintenance on your septic system and be sure to address any problems quickly.

To conserve water:

  • Landscape using native plants - they require less maintenance and are drought-resistant!

  • Save money on your water bills by installing a drip irrigation system

  • Learn more about local water issues on our Water Conservation page!

If you're interested in helping us to monitor and identify sources of pollution in our surface waters, check out our Confluence Crew Water Quality Monitoring Program!

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