Rain falls on our roofs and streets and flows into storm drains. Whatever goes down the drains flows to our creeks and lakes. Rain water picks up what it touches - oil from the road, yard chemicals, pet waste, or other pollutants. This polluted water then runs off into our creeks and lakes and Puget Sound. There is no filter or treatment to clean the water. This polluted water can be highly toxic to our fish and wildlife. When houses, streets, shopping centers, and businesses are built, natural soil and plants are replaced by hard surfaces, such as roofs and pavement. When rain falls on these hard surfaces, it cannot soak into the ground, so it quickly becomes runoff that can cause flooding. Because this runoff does not have a chance to be filtered through soil and plants, which are natural filtration systems, this runoff enters our water bodies with all the pollutants it picked up along the way, causing water quality problems in addition to flooding.
Low Impact Development (LID) is an approach to land development and redevelopment designed to infiltrate runoff from rain using techniques that imitate natural systems. It can reduce water pollution, reduce flooding, and add green spaces - and it is also required as part of the city’s stormwater management permit with Washington State's Department of Ecology.
To get a sense for how each LID strategy works, click on the links below.