Stormwater 101

Stormwater issues are a top priority for the Environmental Protection Agency (EPA), and many regulations have been created to ensure stormwater is properly managed. If left unchecked, stormwater can cause flooding and pollute waterways.

Stormwater runoff occurs when rain or snowmelt flows over the ground. Development – buildings, streets, parking lots, and loss of trees and natural filters – inhibit stormwater from soaking into the ground. That leads to increased runoff volume, rates, and more pollution – in the stormwater and our waterways.

Stormwater runoff picks up debris, dirt, and pollutants from impervious surfaces and washes them into storm sewers. Anything that enters a storm sewer flows into rivers we use for swimming and drinking water. In Georgia, stormwater runoff is the pollution source for 98 percent of all "impaired" waters identified by the state.

Debris, dirt and pollutants in stormwater runoff can have adverse effects on animals, plants, and people. Sediment can cloud the water, destroy aquatic habitat, and increase water treatment costs. Excess nutrients, such as lawn fertilizer, can cause algal blooms. Bacteria and other disease-causing organisms can wash into lakes and streams and create health hazards. Hazardous chemicals such as oil, household pesticides, auto fluids, and paint solvents can poison aquatic life.

To combat these adverse affects, regulations have been passed requiring states, local governments, and industry to manage stormwater. The primary method is through best management practices (BMPs), which schedule activities, prohibit practices, provide operating and maintenance procedures, treatment requirements, and other techniques to prevent or reduce the discharge of pollutants to our waters.

Stormwater regulations are addressed in the National Pollutant Discharge Elimination System(NPDES), a federal mandate and section 402 of the Clean Water Act. Although a federal law, most states implement this program and issue permits authorizing the discharges of stormwater. In Georgia, the NPDES permitting authority is the Environmental Protection Division (EPD). NPDES permits are required for local governments, industrial activities, and construction activities.


Under the NPDES stormwater program, operators of large, medium and other regulated small municipal separate storm sewer systems (MS4s) must be authorized to discharge stormwater to Waters of the State. An MS4 is a city or county drainage system that includes roads, gutters and pipes to collect and move stormwater. Cities and counties with MS4 drainage systems are required to develop a stormwater management program to prevent harmful pollutants from being washed by stormwater runoff into local water bodies. The City of Johns Creek has developed and implemented such a stormwater management program.

Industrial Activities 

Activities that take place at industrial facilities, such as material handling and storage, are often exposed to precipitation and stormwater. As runoff from rain or snowmelt comes in contact with these materials, it picks up petroleum or chemical pollutants and carries them to nearby sewer systems, rivers, lakes, or coastal waters. To minimize the impact of stormwater discharges from industrial facilities, the NPDES program includes an industrial stormwater permitting component. Operators of industrial facilities that discharge or could discharge stormwater to a municipal separate storm sewer system (MS4) or directly into waters of the United States must have an NPDES industrial stormwater permit. These industrial permits require periodic inspections, water sampling, and reporting.

Construction Activities 

Stormwater runoff from construction activities can also have a significant impact on water quality. As stormwater flows over a site, it picks up sediment, debris, and chemicals. Polluted stormwater runoff can poison fish and other wildlife. Sedimentation can bury aquatic habitat, and high volumes of runoff can cause streambank erosion. The NPDES Construction Stormwater program requires operators of construction sites one acre or larger (including smaller sites that are part of a larger common plan of development) to obtain an NPDES construction stormwater permit. The permit focuses on stormwater pollution prevention but is primarily focused on erosion and sediment control.

While EPD is the state regulatory agency that issues the NPDES construction permits, local governments and even regional planning organizations can impose more stringent requirements and development regulations. The Metropolitan North Georgia Water Planning District has developed regional and watershed-specific plans for stormwater management, wastewater management, and water supply and conservation in a 16-county area around metro-Atlanta, including Johns Creek. Local governments within the district are required to adopt the regulations and enforce them.

If you have any stormwater management questions, please email or call the City of Johns Creek Stormwater Management Department at 678-512-3200.