More Than Just Dirt: The Science Behind Sediment Pollution

Sediment pollution is one of the leading causes of water pollution in the U.S. and results in more than $16 billion in environmental damage every year!

Failing Silt Fence. Source: Knox County Tennessee, Muddy Runoff in Road. Source: Knox County Tennessee, Agricultural Runoff. Source: Treehugger

What is Sediment Pollution?

Sediment is fine-grained particles of silt and clay. Sediment pollution occurs when the soil is eroded by being worn away by wind, water, or human activities. While these silt and clay particles occur naturally in bodies of water, an excessive amount of sediment can disrupt the natural systems and pollute our waterways.

What Causes Sediment Pollution?

  • Agricultural tilling of steep slopes causes soil erosion.

  • Construction sites and mining operations often expose large areas of soil, making them vulnerable to erosion during rainfall.

  • Deforestation leaves the soil exposed and unprotected from the erosive forces of wind and water.

  • Unpaved roads and inadequate drainage systems contribute to sediment runoff.

  • Impervious surfaces in urban areas, such as roads and buildings, increase the volume and velocity of stormwater runoff, leading to increased erosion and sediment transport.

  • Natural disasters like floods or landslides displace large amounts of sediment into waterways.

Consequences of Sediment Pollution

  • Harms aquatic life by:

    • Depleting oxygen levels

    • Disrupting aquatic plants’ growth

    • Clogging fish gills

    • Blocking access to food

    • Disrupting food chains and reproduction

    • Destroying habitats 

    • Impairing fishes’ vision to find food and avoid predators

  • Harmful to humans by:

    • Contaminating drinking water and increasing treatment costs

    • Increasing exposure to waterborne diseases and pollutants

    • Causing respiratory problems, skin irritation, and gastrointestinal issues when sediment-laden water is used for drinking or bathing

    • Reducing recreational opportunities and making navigation more difficult

    • Increasing flooding from filling storm drains and catch basins with sediment

Installation of Storm Drain Filter. Source: Grainger

Floating Turbidity Curtain. Source: Duraflex

Best Management Practices for Construction Sites and Agriculture

  • Stake silt fences to contain sediment.

  • Install storm drain filters to catch sediment, litter, heavy metals, oils, and fuels.

  • Avoid mowing riparian buffer zones (vegetation that filters runoff and stabilizes soil to prevent erosion) along the banks of streams, rivers, and lakes.

  • Practice no-till farming.

  • Plant cover crops to protect the soil when the main crop is not growing.

  • Plow and plant crops along the contour lines of a slope to reduce runoff velocity.

  • Create level platforms on steep slopes to reduce erosion.

  • Have an erosion and sediment control plan in place. 

  • Cover disturbed areas with mulch or vegetation.

  • Install turbidity curtains in waterways.

  • Use methods to suppress sediment dust.

Storm Drain With Slogan “Only Rain Down The Drain”. Source: Arlington Virginia

What You Can Do

  • Avoid overwatering your plants.

  • Cover exposed soil with vegetation or mulch.

  • Direct stormwater runoff away from impervious surfaces (driveway, road, or roof) and into vegetated areas.

  • Plant trees and shrubs to stabilize soil and reduce erosion.

  • Purchase locally grown produce from farmers who use sustainable farming practices.

  • Dispose of waste properly to prevent pollutants from entering waterways.

  • Sweep sidewalks and driveways instead of hosing them off to prevent sediment and other pollutants from running off into waterways.

  • Notify your local stormwater department when you see sediment entering streets or streams near a construction site. 

  • Avoid mowing within 10 feet from the edge of a stream to protect the riparian buffer zones.

  • Wash your car at a commercial car wash or on a surface that absorbs water, such as grass or gravel, to prevent sediment and soap from entering waterways.

Riparian Buffer. Source: Inspired Pencil

Mya Moseley