Types of Pollution

Pollutants enter the water environment form two main sources: point and not point sources – also referred to as direct and indirect flows.

Illicit Discharge

An Illicit discharge is defined in the federal regulations as: … any discharge to an Municipal Separate Storm Sewer System (MS4) that is not composed entirely of storm water.

  • Direct: Flows in the storm drains by illicit/improper connections between sanitary sewer and storm drain systems.
  • Indirect: Flows in the storm drains created by pollutant that enter the storm drains system through an inlet or illicit connections.

Examples of Illicit Discharges


  • Sewage cross-connected with storm drains
  • Industrial and commercial cross-connected to storm drains


  • Spills that enter the storm drains system at an inlet
  • Dumping liquid into a storm drain inlet (i.e. paint, oils)
  • Outdoor washing activities that create flow to a storm drain (i.e. car washing hosing driveways)
  • Irrigation from landscaping or lawns to storm drains

The Center for Watershed Protection has detailed guidance and advice. Check out the link for more info. http://www.cwp.org/

Lawn and landscape maintenance: herbicides, pesticides and fertilizers

One quarter of the pollutants found in streams and rivers originate from residential use of herbicides, pesticides and fertilizers. These materials can enter into the storm drain system through illegal dumping, run-off from excess lawn irrigation, and from heavy rains and from there they can be discharged directly into our waterways. Herbicides are defined as a chemical substance that kills plants, weeds or inhibit their growth. A pesticide is any mixture or substance intended for preventing, destroying, and/or repelling pests. Fertilizer is defined as any substance containing one or more plant nutrients design to promote plant growth.

Used Automotive Fluids and Toxic Chemicals

Automotive Fluids

Small amounts of car fluids (oil, antifreeze) can contaminate our streams and rivers killing fish and other aquatic life. Of all Americans who change their own oil, only 10% of them dispose of their waste oil in the proper Manner. Recycling is an economical way of protecting our rivers and helping our environment.

Toxic Chemicals

Did you know that improper handling, storage and disposal of chemicals (i.e. cleaners, paints, paint strippers, thinners etc.) can contaminate storm water. Read product label for safe use and disposal. Click to view or download info on recycling fluids

Soil Erosion and Sedimentation

The Clean Water Act categorized and identified Soil Erosion and Sedimentation as the “single non point source pollution with the greatest detrimental impact on water quality and the environment.

  • Increase turbidity and reduces light causing a decline in plants aquatic plans and organisms.
  • Covers fish eggs, spawning beds and fills pools covering food sources.
  • Sediment reduces the depth of streams and can increase flooding.
  • Sediment carries nutrients that promote excess aquatic vegetation growth and depleting oxygen levels for other organisms.

Leave a Reply

Your email address will not be published. Required fields are marked *