Studies have shown that dry weather discharges from the storm sewer system (flows unrelated to precipitation) can contribute a larger load of some pollutants than wet weather stormwater discharges (EPA, 1983 and Duke, 1997). Such illicit discharges include, but are not limited to, non-permitted sanitary sewage, garage drain effluent, and waste motor oil.
Detecting and eliminating these illicit discharges involves complex detective work, which makes it difficult to establish a rigid prescription for how to conduct an Illicit Discharge Detection and Elimination (IDDE) Program.
Communities first need to understand their storm sewer infrastructure and map all the outfalls. When illicit discharges are identified, they need to be removed. The process is ongoing, and the effectiveness of a program is expected to improve over time. In fact, IDDE programs can benefit from and contribute to other community-wide water resource programs, such as public education, stormwater management, stream restoration, and pollution prevention.
Develop, implement and enforce a program to detect and eliminate illicit discharges into the MS4.
Develop and maintain a map showing the location of all outfalls and the names and location of all waters of the U.S. that receive discharges from those outfalls.
Prohibit, through a law or other regulatory mechanism, illicit discharges into the storm sewer system and implement appropriate enforcement procedures and actions.
Develop and implement a program to detect and address non-stormwater discharges to the system.
Inform public employees, businesses and the general public of hazards associated with illegal discharges and improper disposal of waste.
Address the following categories of non-stormwater discharges as necessary if they are determined by DEC to be substantial contributors of pollutants.
- Water line flushing
- Landscape irrigation
- Diverted stream flows
- Rising groundwater
- Uncontaminated groundwater infiltration
- Uncontaminated pumped groundwater
- Discharges from potable water sources
- Foundation drains
- Air conditioning condensation
- Irrigation water
- Water from crawl space and basement sump pumps
- Footing drains
- Lawn watering
- Individual residential car washing
- Flows from riparian habitats and wetlands
- Dechlorinated swimming pool discharges
- Street wash water
- Fire fighting activities
MS4s detect, map, and eliminate all illicit discharges.
MS4s assess adequacy of local laws in addressing stormwater needs.
Illicit discharges are prohibited and enforcement procedures are in place and being implemented.
Dischargers comply with the illegal discharge elimination plan and statutory prohibition.
The public and other target groups are informed of hazards from illegal discharges.
MS4s work together to improve program efficiency.