A rain garden is any landscaping that receives and soaks up stormwater (rainwater) runoff from an impervious surface such as a parking lot, street or roof.
What do rain gardens have to do with Cougar Creek?
Stormwater (rainwater) runoff is one of the most devastating problems for all urban and suburban creeks. Cougar Creek is no exception.
Whenever it rains, a flash flood of stormwater runoff enters the creek via catch basins and culverts (engineering terms for drains and pipes) — carrying with it tailpipe toxins, brake and tire dust, road salt, excess fertilizers and pesticides, cigarette butts, plastic and paper litter, and whatever else can be swept along by flowing water. This toxic brew sweeps through Cougar Creek, into the Fraser River and out to the ocean.
The pollutants in stormwater harm fish health, the sediments suffocate spawning gravels where salmon have laid their eggs, and the sheer volume of water can wash away fish eggs, erode streambanks and destabilize the streambank shade trees that are critical for salmon.
Groundwater levels fall, because the rain or snow that would normally replenish groundwater has been quickly piped away to the ocean. With insufficient groundwater supplies to last through summer, creek water levels fall dangerously low and water temperatures become dangerously high, threatening fish survival.
The solution? Get more rainwater infiltrating into the ground, as nature intended, so as to restore a steady seepage of cool, soil-filtered water into the creek. One way to accomplish this is to create “rain gardens” – landscaping that absorbs rainwater runoff from hard surfaces such as roofs, driveways, parking lots and streets.
While the environmental benefit of a single rain garden is negligible, the combined benefits of many such gardens can make the difference between salmon survival and salmon extinction in Cougar Creek.