Pollution Prevention

What are non-point source storm water pollutants?

Non-point source (NPS) pollution occurs when rain or melting snow carry pollutants such as contaminated soil, fertilizers, salt or animal waste into the sewer system. These pollutants are called non-point source because it is not always possible to identify their origins. While we sometimes want to point the finger of blame at industry, the fact is that we all contribute to non-point source pollution when we dispose of household hazardous wastes through the sewer system, over-fertilize our lawns and gardens, leave pet waste unattended or allow our cars to leak automotive fluids onto Evanston streets and parking lots.

What are some more examples?

Pollutants can come from a variety of places both in and around our homes and businesses:

Pollutant: Sand, and clay particles, other debris
Source: Construction sites; bare spots in lawns and gardens; wastewater from washing cars and trucks on driveways, parking lots, or streets.

Pollutant: Nutrients
Source: Overused or spilled fertilizers; pet waste; and grass clippings that enter the street sewers.

Pollutant: Diseased organisms
Source: Pet waste and garbage

Pollutant: Hydrocarbons
Source: Car and truck exhaust; leaks and spills of oils and gas.

Pollutant: Pesticides
Source: Spills and leaks, or pesticides applied before a rainstorm

What are non-point source storm water pollutants?

Pollutant: Metals
Source: Cars and trucks (tire wear, brakes, exhaust); galvanized metal gutters and downspouts

Where do these pollutants go?

Evanston has a combination sewer system. This means that the contents of the sewers in the streets are mixed with the contents of household sewers.

All of these wastes are sent to the water treatment plant operated by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC). There, these wastes are treated to lower pollution levels and returned to the river system. Treated wastewater from Evanston eventually flows into the Illinois River and then into the Mississippi River and the Gulf of Mexico. So, what happens in Evanston and other Chicago-area communities affects both the quality of river water and the quality of life for other residents of Illinois and the United States. During severe rainfalls, when the water system backflows, untreated sewage and pollutants, although highly diluted, are discharged directly into Lake Michigan, Evanston’s source of drinking water. While these backflows are rare, they do occasionally occur.

What happens to pollutants at the water treatment plant?

When pollutants enter the plant, the normal treatment process is slowed down. Particles that would normally disappear after one hour may still remain in the system six to eight hours after arrival. As we all know, time is money. The cost to treat pollutants is high, and this cost is passed on to you through taxes paid to MWRDGC. One way of reducing taxes is to reduce the amount of pollutants entering the sewer system.

How can I reduce NPS pollution?

  1. Properly dispose of household hazardous wastes such as motor oil, antifreeze, gasoline, drain cleaner, mildew remover, mothballs, lead-acid batteries, chemicals, paint and thinners. City of Evanston refuse collection crews will not collect hazardous waste products. Residents should call the Solid Waste Agency of Northern Cook County at (847) 296-9205 to find out the locations, times and dates of the nearest household hazardous waste disposal sites. Information is also available of the City of Evanston website, cityofevanston.org.
  2. Dispose of used motor oil from cars and lawn equipment at local service stations or quick oil change businesses. Call the business before transporting the oil for disposal.
  3. Apply the right amount of fertilizer to your lawn. Soil testing kits that measure nutrients and pH levels are available through your local nursery. Avoid applying fertilizers before a heavy rainstorm that will cause nutrients to wash away before they are absorbed into the soil.
  4. Keep your mowing height at 3 inches. Taller grass holds more water, requires less irrigation, and helps to shade out weeds. Prevent grass clippings from entering the sewer by leaving them on the lawn. Grass clippings are a natural fertilizer, and they are free!
  5. Clean up pet wastes to prevent nutrients and bacteria from entering the sewer system. Remember, City ordinance prohibits dog owners from allowing their pets to defecate on public streets, sidewalks or parks unless the waste is completely and immediately removed.
  6. Wash your car with a no-phosphate detergent. Better yet, take your car to a local car wash where water is recycled.
  7. Check for drips under your car or truck and repair leaks immediately to keep oils off pavement. During the summer months, when gas can expand, take care not to overfill gas tanks, or fuel might spill out on streets or driveways.
  8. Direct roof downspouts away from driveways and foundations and towards your lawn and garden. Use a splash block directly below your downspout to help prevent soil erosion.
  9. Plant native trees, grasses, and flowers in your yard. These plants require less water, and their root systems hold the soil in place. The Chicago Botanic Gardens is a great place to view native plants. Consider a visit to the gardens before purchasing a tree or plant for your garden.
  10. Clean up litter from your home, business, school, neighborhood, or park. When it rains, water flows over everything on the ground and washes it all into Evanston’s combined sewer system.

MWRDGC 24 Hour Hotline

The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) receives and treats the sewage from the City of Evanston. The District has established a 24 hour hotline to report the dumping of hazardous material into the sewer system. This number was established in an effort to reduce the possibility of contamination of waterways, poisoned fish and wildlife, and damage to the biological process of the waste water treatment plant. The hotline is 1-800-332-DUMP.