Runoff Problem

Stormwater runoff is a common source of pollution in streams, lakes and rivers because of this stormwater runoff is of particular concern in urban areas.

Large expanses of surfaces impervious to water, such as roofs and parking lots, make it difficult for precipitation to soak into the ground. As stormwater moves over the land and towards streams, rivers and lakes, it can be contaminated with a number of substances, such as:
  • Sediment from construction sites, eroding road-banks and stream-banks.
  • Organic materials, such as leaves, grass clippings and other yard wastes. When these substances are washed into streams and lakes, they decay - using oxygen in the process. This can use oxygen needed by fish and other aquatic organisms.
  • Oil and gasoline leaked from automobiles and storage tanks.
  • Nutrients, such as phosphates and nitrates. Often these can be traced to fertilizers washed off lawns and from failing septic systems. When nutrients enter water, they can stimulate the growth of unwanted aquatic weeds and algae.
  • Pesticides, from lawns and gardens.
  • Pathogens, such as bacteria and viruses, which can cause disease. These may come from improperly disposed human and animal wastes and failing septic systems.
  • Other toxic substances, such as copper or lead. These may come from spilled or improperly disposed paint, or be deposited back on the land from automobile emissions.
  • Trash and street garbage, such as plastics, paper and other litter.
Besides causing pollution problems, stormwater runoff also contributes to and aggravates flooding problems. The less precipitation that soaks into the soil, the more there is to run into the streams. When to much water enters a stream all at once, flooding results.