Stormwater pollution from point sources and nonpoint sources is a challenging water quality problem. Unlike pollution from industry or sewage treatment facilities, which is caused by a discrete number of sources, stormwater pollution is caused by the daily activities of people everywhere. Rainwater and snowmelt run off from streets, lawns, farms, and construction and industrial sites and pick up fertilizers, dirt, pesticides, oil and grease, and many other pollutants on the way to our rivers, lakes, and coastal waters. Stormwater runoff is our most common cause of water pollution.
Because stormwater pollution is caused by so many different activities, traditional regulatory controls will only go so far. Polluted storm water runoff is often transported to municipal separate storm sewer systems(MS4s) and ultimately discharged into local rivers and streams without treatment. EPA’s Storm Water Phase II Rule establishes an MS4 storm water management program that is intended to improve the Nation’s waterways by reducing the quantity of pollutants that storm water picks up and carries into storm sewer systems during storm events. Common pollutants include oil and grease from roadways, pesticides from lawns, sediment from construction sites, and carelessly discarded trash, such as cigarette butts, paper wrappers, and plastic bottles. When deposited into nearby waterways through MS4 discharges, these pollutants can impair the waterways, thereby discouraging recreational use of the resource, contaminating drinking water supplies, and interfering with the habitat for fish, other aquatic organisms, and wildlife.
Education and outreach are key components to any successful stormwater program.
What Are the Phase II Small MS4 Program Requirements?
Operators of regulated small MS4s are required to design their programs to:
Reduce the discharge of pollutants to the “maximum extent practicable” (MEP); Protect water quality; and satisfy the appropriate water quality requirements of the Clean Water Act. Implementation of the MEP standard will typically require the development and implementation of BMPs (Best Management Practice) and the achievement of measurable goals to satisfy each of the six minimum control measures.
The Phase II Rule defines a small MS4 storm water management program as a program comprising six elements that, when implemented in concert, are expected to result in significant reductions of pollutants discharged into receiving waterbodies.