Surface Water Quality Program

National Pollutant Discharge Elimination System (npdes)

The Municipal Separate Storm Sewer System (MS4) National pollutant Discharge Elimination System (NPDES) is a federal program designed to reduce stormwater pollutant discharges to receiving waters of the United States.

The US Environmental Protection Agency (EPA) required that Seminole County, as well as the 7 cities within the County apply for and receive a MS4 NPDES permit. The overall goal of this permit, as part of the Federal Clean Water Act, is to reduce the amount of pollutants in stormwater runoff that is discharged directly into natural waterbodies, streams and river systems. This goal is achieved through a comprehensive stormwater program that includes water quality and biological monitoring, watershed and pollution prevention education and water quality improvement projects. The County is required by our MS4 NPDES permit to track all of our NPDES tasks throughout the year and to summarize them in an annual report which is submitted to the Florida Department of Environmental Protection (FDEP).

The NPDES goal of pollution prevention is also achieved through state regulations that were implemented in the 1980’s, which require developments to construct stormwater systems that provide water quality treatment for stormwater runoff typically in the form of a stormwater pond. Stormwater requirements associated with development are permitted either through the St. Johns River Water Management District (, the Florida Department of Environmental Protection ( as well as any necessary County development permits (

As part of the County’s NPDES permit compliance program, we sample lakes and rivers throughout the County. For more detailed information on water quality throughout the County please visit the Seminole County Watershed Atlas (

Common NPDES links:

Below are some commonly asked questions concerning stormwater and NPDES:

What are the effects of stormwater runoff? Stormwater runoff is the transport vehicle for pollutants. Any dirt, oil, grease, fertilizer or other pollutants on the ground can be picked up by stormwater runoff and carried into the stormdrains, lakes and rivers. These pollutants may include nutrients which provide food for unwanted aquatic plants like hydrilla and algae. Excessive algal growth can lead to decreased oxygen in the water that fish need to breath, resulting in fish kills. Bacteria and other pathogens from pet waste can create serious health hazards in ponds and lakes.

What’s the difference between a storm drain and a sewer drain? The sewer drain and storm drain are two completely separate drains that go into two separate systems. The sewer drain and sewer system takes all household wastewater and routes it through a plumbing system into a wastewater treatment plant. Some examples of sewer drains you may see are in the wash area at the back of a restaurant and the drain in the floor of a public restroom. The storm system routes rainwater off the streets into a storm drain which empties into a stormwater pond or directly into a river, ditch or lake. Some examples of storm drains you may see include the open curb inlet along roadways and the square storm grate commonly seen in parking lots.

What is a stormwater pond? You probably walk, cycle or drive by a stormwater pond almost every day. There are two main types of stormwater ponds, a detention pond which typically has water in it most of the year. These are the ponds that people often refer to as their neighborhood lakes. However, these ponds play a critical role in managing our surface water quantity and quality. Stormwater detention ponds are designed and constructed to reduce flooding and play an important role by catching and filtering polluted run-off from roads, parking lots and overfertilized lawns. While some pollutants biodegrade within the stormwater pond, others are more persistent and accumulate in the sediment. Therefore, one should never swim or eat fish from a stormwater detention pond. A stormwater retention pond is typically dry and usually only has water in it for a few days after a rainstorm. These retention ponds also are designed to reduce flooding and filter stormwater runoff. The stormwater filters through the sand bottom and eventually enters the groundwater.

What is an illicit or illegal discharge? Any substance released into the separate storm water drainage system that is not composed entirely of stormwater or uncontaminated groundwater. Examples of illicit discharges include dumping of motor vehicle fluids, household hazardous waste, paint, grass clipping, leaf litter or animal waste. Exemptions of allowable discharges are listed in Seminole County code Sec 270.400. at

If you witness or think an illicit discharge is taking or has taken place, please call Seminole County at 407-665-ROAD or report it through the County’s Watershed Atlas at

Pollution Discharge Pic Report illicit discharge or dumping at:

Or call: 407-665-ROAD (7623)
Waterways Video Link Pic Watch the Video: Preserving Our Waterways