Stormwater runoff is water from rain or melting snow. It flows from rooftops, over paved streets, sidewalks, and parking lots, across bare soil, and through lawns and storm drains. As the water flows, runoff collects and transports soil, pet waste, salt, pesticides, fertilizer, oil and grease, litter, and other pollutants. These small amounts of pollution can add up to a big problem when it comes from an area the size of Kansas City. Each pollutant can have harmful effects on wildlife, recreation, and forestry.

Some sewer back-ups and wastewater overflows are caused by water that doesn't belong in the sanitary sewer system. During wet weather, stormwater or groundwater gets into the pipes that are designed to carry wastewater. When this happens, the mix of wastewater, stormwater and groundwater may exceed the system's capacity and has to go somewhere. Unfortunately, the excess flow can force open manholes in the streets, cause water to overflow into nearby streams and even back-up into citizen's basements, making it a public health and safety issue as well as an environmental issue that impacts all Kansas Citians.