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Tips for reducing runoff Building homes, roads and stores means removing vegetation and paving large areas. As we pave and seal more and more land, we allow less and less rain to infiltrate the soil and recharge groundwater supplies. This infiltration through the ground helps clean the water and feeds underground water flows – aquifers – that supply drinking water and keep streams flowing during the summer. Paved surfaces also increase the force and volume of water that rushes into streams, eroding banks and scouring away fish habitat. Plant another tree. Trees and shrubs capture and hold lots of rain before it reaches the ground. Wherever possible, keep the existing trees and shrubs and plant more. Avoid paving your lot. Leave as much of your lot as you can in natural vegetation and trees – even lawns can add to the runoff problem. If you must pave, consider using modular asphalts – water seeps through them! Recharge groundwater supplies – instead of the storm drains. Find out if your lot’s drainage plan requires that your downspouts flow directly to the storm drain system. If not, redirect them away from gutters, storm drains or sanitary sewers and toward French drains (gravel filled trenches) or "splash blocks" in your yard that help water soak into the ground slowly. Not only will this allow water to filter naturally into groundwater supplies, it may reduce the burden on streams or the wastewater system. Note: To find out about your drainage plan, visit the King County Department of Development and Environmental Services (DDES) residential permit counter. Get directions at (206) 296-6600. Do not redirect your downspouts if water ponds in your yard or if you or your neighbors use septic tanks. Don’t strip away ground cover. Unprotected dirt will wash off your lot and fill catch basins, pipes and streambeds with sediments. If you must remove plants, control erosion with jute matting, straw or hay bales. Avoid landscaping plastic and use bark wisely. Landscaping plastic blocks infiltration and creates runoff just like streets or concrete. When used on top of plastic, bark creates additional problems, clogging storm drains, lowering the pH of streamwater, and breaking down into fibers that harm fish gills. Do use bark without plastic, as long as you: 1) don’t spray chemicals on or around bark; 2) don’t use bark on steep slopes; 3) surround bark with a barrier like lawn edging; and 4) keep bark away from streams, driveways and gutters. » Home & garden hints Updated: June 21, 1999 ESA home | What we're doing | What you can do | Resources Salmon Information Center (external link) King County | Executive | News | Services | Comments | Search Links to external sites do not constitute endorsements by King County. By visiting this and other King County web pages, you expressly agree to be bound by terms and conditions of the site. The details.