Exempted and Conditionally Exempted Discharges

All NPDES stormwater permits require municipalities to effectively prohibit the discharge of non-stormwater into storm drains. Certain non-stormwater discharges, such as flows from riparian habitats, wetlands, springs, or unpolluted groundwater, are exempted (i.e., allowed to discharge to storm drains with no control measures). Other non-stormwater discharges, known as conditionally exempted discharges (CEDs), are allowed to discharge to storm drains only if certain measures are taken to control potential pollutants in the discharge.

The Program’s NPDES permit includes a list of CEDs that are not prohibited from discharge to storm drains if they are identified as not being sources of pollutants to receiving waters or if appropriate control measures are developed and implemented to prevent or eliminate adverse impacts of such sources. In accordance with the permit, Co-permittees must identify the categories of CEDs from this list that they want to exempt, and describe for each category either why it is not a source of pollutants or what control measures will be used to eliminate adverse impacts from that category.  To address this requirement, the Program developed a Conditionally Exempted Discharges Report (June 15, 2000) that describes the approach for each category of discharge.

The Co-permittees are currently implementing the BMPs described in the CED Report. They have made the BMPs part of their standard operating procedures for municipal activities. They are requiring businesses and contractors and encouraging residents to comply with these BMPs, and they have included the BMPs in conditions of approval for development projects where applicable.