Stormwater runoff is excess rain or snowmelt that is not absorbed into the ground, but instead runs into surrounding waterways. Runoff results from two main factors: the inability of a surface (e.g., pavement) to absorb water and/or the amount of precipitation exceeds the absorptive ability of the surface. Runoff can erode landscapes and damage structures, and it can pick up a wide variety of pollutants and carry them to surrounding waterways, thereby contaminating the waterway. Contaminated water can be detrimental to human health, environmental health, and recreation. The intensity of runoff and its effects may increase with climate change.
- The occurrence and effect of stormwater runoff is site-specific. Mitigation requires surveying and designing for the specific needs of the site.
- Combined rainwater and sewer systems require special mitigation consideration.
- In the Midwest, climate change is projected to increase the frequency and intensity of storms, resulting in increased runoff and associated pollution.
- Because specific regional features contribute to the overall impact of stormwater runoff, different Missouri regions may experience different types and magnitudes of stormwater consequences.
- The effects of stormwater runoff have been better researched in urban settings. Consequently, there is more uncertainty about the effects of runoff in rural settings.