Stormwater Straight Talk: Sediment – most common stormwater pollutant

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  • 78th Air Base Wing Public Affairs

Not only is sediment found everywhere on land, but it is also the most common pollutant in streams, rivers, and bodies of water.

Sediment is made up of soil particles that have detached from land through erosion. The soil particles can come from sand, gravel and clay and are transported by water, wind, ice or gravity. Stormwater runoff can transport sediment from bare soil until it eventually reaches water bodies.

Once sediment reaches water bodies, it can affect water quality in a number of ways.

Small sediment particles can remain suspended in the water column. Suspended sediment increases the turbidity of water and causes it to be cloudy, affecting plant growth, animal development and the quality of potential drinking water. Cloudy water obstructs sunlight and inhibits photosynthesis of aquatic plants, limiting the amount of natural vegetation. Murky water also clogs fill gills, reducing oxygen absorption and development, and prevents animals from being able to see food, potentially disrupting the food chain.

Sediment can also be deposited onto the streambed, which can alter flow paths. Sedimentation is the process of sediment build up in the stream bed, and it can also negatively affect aquatic life by clogging the spaces between larger gravel, cobbles and boulders.

Sediment poses an additional risk, because it often carries other pollutants, such as nutrients, heavy metals, organic chemicals, bacteria and other pathogens. Water with high levels of sediment and other pollutants is more expensive and more time consuming to treat. According to the United States Environmental Protection Agency, sediment pollution causes over $10 billion worth of damage annually.

Human use of land accounts for approximately 70% of sediment pollution. Here are some easy ways to help reduce sediment pollution:
- Seed bare spots in the landscape
- Use weed-free mulch in your garden or lawn
- Use a straw or erosion control blankets if restarting or tilling a lawn
- Put compost or weed-free mulch on your garden to help keep soil from washing away
- Avoid mowing within 10 to 25 feet from the edge of a stream or creek to help minimize erosion
- Sweep sidewalks and driveways instead of hosing them off and properly dispose of swept material
- Wash your car at a commercial car wash
- Utilize sediment control measures, such as silt fence, on construction projects
- Notify local government officials if you notice sediment dispersion from construction sites

For more information, call 478-926-9645.

Editor's note: Stormwater Straight Talk is a quarterly column intended to educate and inform base personnel and families about stormwater management.