Stormwater runoff occurs when precipitation flows across roads, parking lots, roofs and other impermeable surfaces. As the water travels across the land, several pollutants are picked up. These can include fertilizer, pesticides, hazardous chemicals, pet waste, sediment, and bacteria. Of particular concern is animal waste being washed away from CAFOs. Since the water is not able to be soaked into the ground, where it would undergo a natural filtration process, contaminated water enters our waterways.

Problems caused by stormwater runoff include:

  • Oysterbed closures¬†Oysters are filter feeders, meaning when they eat, they remove pollutants from the water. This makes them an important part of our ecosystem. Oyster fishing is an important piece of our economy and culture as well. However, if too much pollution is present, oysters may become unsafe to eat. ooo
  • Eutrophication occurs when too many nutrients, like nitrogen and phosphorus, are carried into the water from fertilizers and animal waste. This abundance of nutrients can cause excessive growth of algae, known as an algal bloom. When too many algae grow, the water becomes oxygen-depleted and creates a “dead zone”. This leads to fish kills, loss of other plants and wildlife, and can increase levels of toxic algae. kkkkkkkkkkk
  • Siltation¬†is when too many sediments enter the water, like clay, silt, and soil. These can be sourced from areas of construction, development, and soil erosion. When these materials build-up, it can change the conditions of a water body. Water becomes murky so animals may not be able to find food and aquatic plants may not be able to get adequate sunlight. Fish gills can be clogged. Small organisms may die, affecting the food chain. Too much sediment can even alter flow and depth.lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll
  • Threats to human health Following rain, fecal bacteria levels can be elevated. E. coli is found in freshwater sources, while Enterococcus bacteria have a higher tolerance to saline water. These bacteria are naturally found in the environment, but heightened levels due to humans and/or agriculture can pose health dangers for human and wildlife populations. The contact and ingestion of waters with heightened levels of E. coli and enterococcus bacteria can lead to rashes, gastrointestinal infections, nausea, and vomiting.

Here’s what you can do…

  1. Properly dispose of household hazardous products like cleaners and paint and only use as intended.
  2. Use commercial car washes or wash in your yard. Car washing in your driveway can send detergents and automotive fluids into storm drains.
  3. Make your yard a rain garden.
  4. Pick up after your pets.
  5. Properly maintain septic tanks.
  6. Limit fertilizers and pesticide use and compost yard waste.
  7. Talk to your city or town about using pervious surfaces in construction projects.


EPA: Fecal Bacteria

What is Stormwater Runoff?