As stormwater flows off the land, wetlands act as “kidneys” to clean, filter and store the polluted water. Like a sponge, wetlands soak up the excess water, preventing erosion and absorbing nutrients while recharging local groundwater supplies and preventing flooding. Then when it's dry, wetlands slowly release the water that was stored.
At least 50% of the water quality problems in the U.S. result from stormwater runoff. During a storm, the first inch of runoff generally carries 90% of the pollution. Wetlands can store up to 60 days of floodwater. Wetlands can store up to 50 times more carbon than rainforests. The United States has lost more than half of its original wetlands.