Stormwater is water that originates during precipitation events including snow and ice melt. Precipitation can soak into the soil (infiltrate), be held on the surface and evaoporate, or runoff and end up in nearby streams, rivers, or other water bodies (surface water). As environmentalists, we are generally concerned about surface flow - precipitation that evaporates or infiltrates into the ground water has less chance to pick up pollutants from the ground before returning to the water cylce. Stormwater runoff, however, carries chemicals, sediment, and debris such as fertilizer and pesticides from agriculture and motor oil and salt during winter months into nearby rivers, creeks, and storm drains. These impervious surfaces do not allow water to slowly permeate the ground. Infiltration is very important because water that travels slowly to creeks and streams sustains flow in drier spells, which is good for aquatic life. Water that travels slowly through the ground also gets filtered by natural processes before it reaches the water body.
Conversely, impervious surfaces such as paved streets, parking lots, roof tops, and row cropped agricultural land don't allow water to see into the ground so it becomes runoff and travels to the nearest body of water. Water that travels too quickly can pick up and carry a lot more sediment and other pollutants. It also hits creaaks and streams in a rush, which worsens erosion and flooding. In urban areas, as stormwater travels through our gutters, down our streets, sidewalks, driveways, and parking lots into storm drains along the street is transported through stormwater and sewer systems. Learn more about urban stormwater and sewer systems here.
Many people mistakenly assume storm drains carry water to a treatment plant for to be cleaned before it enters our streams, creeks, and rivers, but this is NOT THE CASE! There are simply not enough resources to carry out such a massive task. Most storm drain inlets (except in combined sewer systems - see Sewer Systems and Wastewater) on the streets in your neighborhood transport water after a rain, storm, or snow melt directly to the nearest water body - carrying debris and pollutants from all of the human activities we do with it! Therefore, it is up to US to be WARRIORS fighting for the health of these amazing water resources in Missouri and beyond! Our choices add up. When we don't pick up pet waste, bacteria and nutrients - both harmful to aquatic ecosystems - are carried by stormwater directly to our streams and creeks which flow to larger rivers and ultimately, the ocean. Learn how to be a steward of the waters in your watershed below and take the Watershed Warrior pledge to make clean water choices!
Pollution from cities and towns in Missouri are a significant source of pollution to nearby waterways, the Missouri and Mississippi rivers, and ultimately, the Dead Zone in the Gulf of Mexico. Streets, parking lots, and driveways are impervious - water cannot penetrate them - so they act like a network conveying water carrying pollution from oil, yard fertilizers, chemicals like yard pesticides, and pet waste into storm drains that deposit them directly into nearby waters. We all have a responsibility to do our part to reduce the amount of pollutants in the water entering storm drains in our neighborhoods and communities!
Using phosphorus-free or NO fertilizer, not watering our lawns (which runs off your yard into storm drains carrying fertilizers or nearby pollutants with it), planting native plants (or better yet- a whole rain garden!) that act as pollution filters, and picking up pet waste (EVEN IN YOUR BACKYARD!) are all GREAT ways to reduce your impact on water pollution in your watershed!
Best management practices (BMPs) can lessen the water quality impacts of pollutants carried into the water system after storms or snow melt. For example, pervious parking lots allow water to permeate the surface and increase the time water is in transport to the nearest water body. Another highly effective BMP is the use of vegetation to slow water transport and provide nutrient cycling as the root systems of plants absorb and filter water before it hits the water table beneath the surface and using some of it for their own growth. Vegetative buffers along agricultural fields is an effective way to reduce the surface flow coming off farm fields reducing pollution and erosion in the process. Rain gardens - depressions planted with deep-rooted native plants and grasses near runoff sources - are another effective stormwater management technique. Learn more about St. Louis rain gardens here.