NPDES General Storm Water Permits and Exempt Discharges

The system for regulating wastewater discharges to surface waters was created in 1972 by the Clean Water Act (CWA). The CWA made it unlawful to discharge any pollutant from a “point source” into navigable waters unless an NPDES permit was first obtained.

There are two basic types of NPDES permits: individual and general permits. An individual permit is specifically tailored to an individual facility. A general permit covers a group of dischargers with similar qualities within a given geographical location. General permits offer a cost-effective option for permitting agencies because of the large number of facilities that can be covered under a single permit. The most common of these general permits are for the discharge of storm water.

The Michigan EGLE has developed and has available the following general NPDES permits for storm water discharges:

• Storm Water Discharges from Municipal Separate Storm Sewer Systems (MS4s) - Jurisdictional General Permit

• Storm Water Discharges from Municipal Separate Storm Sewer Systems (MS4) - Watershed General Permit

• Storm Water Discharges Not Associated with Special-Use Areas.

• Storm Water Discharges Associated with Special-Use Areas.

• Storm Water Discharges with Required Monitoring

• Storm Water from Industrial Activity without Required Monitoring

• Storm Water from Industrial Activities

This list is for storm water, only. The entire list includes many more non-storm water discharges, like non-contact cooling water and hydrostatic pressure test water. These storm water discharge permits allow for the discharge of 12 different storm water types:

• Fire hydrant flushing;

• Potable water sources, including water line flushing;

• Fire system testing and fire-fighting training without burned materials or chemical fire suppressants;

• Irrigation drainage;

• Lawn watering;

• Routine building wash-down that does not use detergents or other compounds;

• Pavement wash waters where contamination by toxic or hazardous materials has not occurred and where detergents are not used;

• Uncontaminated condensate from air conditioners, coolers, and other compressors, and from the outside storage of refrigerated gases or liquids;

• Springs;

• Uncontaminated groundwater;

• Foundation or footing drains where flows are not contaminated with process materials such as solvents; and,

• Discharges from fire-fighting activities.

This allowance permits you to

water your lawn, run your air conditioner, drain your sprinkler lines or fire hydrants and discharge this water under your storm water permit.

It should be noted that other discharges are not permitted. Most commonly, we see non-permitted air compressor condensate and have been surprised at how many facilities route their air compressor condensate through the wall and onto the ground outside. If this is the case with your facility, these discharges must be re-routed to the sanitary sewer (with approval of the sewer authority) or an individual permit must be obtained.

Not sure what your obligations are under the NPDES program? CFR personnel have been helping people navigate the NPDES waters (pun intended) for over 30 years. Contact CFR to learn how we can guide you on discharge requirements.