Stormwater is rainfall that does not soak into the ground, but instead flows over the land into creeks, streams, rivers or lakes. As it flows, stormwater runoff collects and transports pollutants such as dirt, oil and grease, chemicals, nutrients, metals, and bacteria to the nearest river or stream. This can result in water quality impairments which can affect human life as well as aquatic life. Although the amount of pollutants from a single residential, commercial, industrial or construction site may seem unimportant, the combined concentrations of contaminants threaten our lakes, rivers, wetlands and other water bodies.
Stormwater runoff is transported through Municipal Separate Storm Sewer Systems (MS4). A MS4 is a system of conveyances owned or operated by a governmental entity that discharges to waters of the U.S. MS4s consist of roads with drainage systems, catch basins, curbs, gutters, manmade channels, or storm drains and are required to obtain NPDES permit coverage for stormwater discharges. The two permits are Phase I (for larger cities) and Phase II (for smaller cities). Griffin is a Phase II community and is required to develop and implement a stormwater management program (SWMP) to reduce the contamination of stormwater runoff and prohibit illicit discharges.
The diagram above shows the change in the percentage of stormwater runoff as impervious surfaces increase. Impervious surfaces are artificial structures, such as pavements (roads, sidewalks, driveways, and parking lots) that are covered by impenetrable materials, such as asphalt, concrete, brick, and stone. As cities grow and more development occurs, the natural landscape is replaced by these impervious surfaces. Stormwater runoff flows across these surfaces and carries pollutants with it, whereas before, natural ground would have helped filter the runoff. An increase of impervious surface means less will seep into the ground or evaporate into the air and more stormwater runoff will flow to local streams, rivers, and lakes.
Non-point source pollution refers to pollution coming from different sources, which are usually everyday activities, and end up in our waterways. As stormwater runoff flows, it picks up sediment and chemicals from yards, driveways, parking lots, rooftops, and streets. These non-point source pollutants include:
Household Waste: Chemicals used in our homes that are not disposed of properly can be hazardous and become a threat to people and the environment. Some examples of Household Hazardous Wastes include:
- Bleach / Household Cleaners
- Paint / Paint Thinner
- Antifreeze / Car Oil
Pet Waste: Pet waste can contain bacteria and produce excess nutrients in local waters. Excessive nutrients will reduce the amount of dissolved oxygen in the water through algae growth. Algae use dissolved oxygen during decomposition and will alter the habitat, effecting fish and other aquatic life that require oxygen. Stations with litter bags and a trash can are located in designate areas around the city. Picking up after pets can have a big impact on the amount of pollution in our waterways.
Yard Waste : Grass clippings and excessive pesticides/fertilizers can contribute to nutrients and organic matter into streams and can clog storm drains. Disposing of yard waste can be through composting or mulching to prevent them from being swept into the street, ultimately going down a storm drain. Using the proper amount of pesticide and fertilizers can also decrease the amount of pollutants. An ounce of prevention is better than a bound of pesticide.
Litter : Debris and other litter are picked up by stormwater runoff and eventually lead to local streams. This debris, such as plastic bags, bottles, and six pack rings, does not only affect us, but also aquatic life. Never throw trash down a storm drain or out of a car. Instead use appropriate trash or recycle bins. The City holds an annual Stream Cleanup for volunteers to collect this debris. Please see Stream Cleanup for more information.
Brochures: These brochures provide more information of what can be done with different waste and other ways of helping prevent pollution.
- Every Drop Counts
- Storm Drains
- Illicit Discharge Ordinance
- Commercial and Industrial Pollution Prevention Program