Permitting is designed to prevent stormwater runoff from discharging pollutants into local surface waters. As I have mentioned in my previous blog, the Clean Water Act authorizes EPA to regulate point sources such as Municipal Separate Storm Sewer Systems (MS4s), Construction Activities and Industrial Activities, that discharge pollutants into waters of the US through the NPDES stormwater program.  While most states are authorized to implement the Stormwater NPDES permitting program, EPA remains the permitting authority in a few states, territories and on most tribal land.

Permits for Construction Activities regulate discharges from construction activities that will disturb one or more acres or are a part of a larger common plan of development or sale if that common plan will ultimately disturb one acre or more. Construction permits are most often issued as a general permit.

Permits for Industrial Activities regulate stormwater discharges associated with one of the eleven categories of industrial activities defined in 40 CFR 112.26(b)(14)(ii) through (xi). The industrial operating stormwater permits are often issued under a general permit.

Municipal Source regulation addresses stormwater runoff that is transported through MS4s and then discharged to local surface waters. MS4 is a conveyance owned by a city or state or a village etc., which is designed to collect stormwater. Note that this conveyance is not a combined sewer nor a part of sewage treatment plants. There are two levels of MS4 permitting.

  • Phase I regulated Permits which apply to medium and large cities with a population of 100,000 or more. Phase I permits are usually individual permits specific to the city.
  • Phase II Regulated Permits apply to MS4s in urbanized areas and outside of urbanized areas and usually are general permits.

Note that in all permit categories an individual permit can be issued to an activity or operation, if the permitting authority determines that an individual permit would better address the discharges from that operation.

Please feel free to contact me if you have any questions or need any assistance regarding the Stormwater Program at  Shri Vani Sripada is a Project Engineer at Smith Management Group.