About Stormwater Permitting

Background and Regulatory Authority

In an effort to preserve, protect, and improve the nation's water resources from polluted stormwater runoff, the RIDEM has developed a Stormwater Program as required by the Clean Water Act (CWA) and RI State Law.

RIDEM’s Stormwater Program addresses requirements from EPA’s National Pollutant Discharge Elimination System (NPDES), and Underground Injection Control (UIC) program under the Clean Water Act, as well as the requirements of the Freshwater Wetlands Regulations, the Water Quality Regulations, the RIPDES Regulations, the Groundwater Discharge Regulations and the RI Stormwater Management, Design, and Installation Rules. The permitting mechanisms are designed to meet the above regulations and laws in order to prevent and minimize stormwater runoff from washing harmful pollutants into groundwater, wetlands, coastal waters, and surface waters such as streams, rivers, lakes, and ponds.

To provide some clarity, potential sources of polluted stormwater runoff are grouped and permitted into 3 categories: municipal separate storm sewer systems (MS4s), construction activities, and industrial activities.

  • Construction Activity

    • Construction and Post-Construction Stormwater. These include discharges of stormwater from disturbed land, as well as post-construction diversions of stormwater to wetlands, rivers, and under the ground. To determine if you need to apply for a Freshwater Wetlands or Stormwater permit, information is found on the Construction Permitting Page.
  • Municipal Separate Storm Sewer Systems (MS4s)

    • Operators of regulated small MS4s (municipal, federal, and state-owned storm sewer systems within "Urbanized Areas" and "Densely Populated Places" with populations (<100,000) may be required to obtain authorization to discharge stormwater. Operators must meet the requirements of the General Permit for Small MS4s and Industrial Activity at Eligible Facilities Operated by Regulated Small MS4s.
  • Industrial Activity

    • Certain industrial sectors may require authorization under the RIPDES industrial permit for stormwater discharges. Operators must meet the requirements of Multi-Sector General Permit for Stormwater Discharge Associated with Industrial Activity.
  • The EPA enhanced the regulation of stormwater discharges under the ground through the Underground Injection Control Program (UIC) with its authority from the Federal Safe Drinking Water Act. The RIDEM utilizes its authority under the Groundwater Discharge Regulations to incorporate safe practices for groundwater supplies. This permitting mechanism is designed to prevent and minimize stormwater runoff from washing harmful pollutants into groundwater that could threaten drinking water supplies.
  • Finally, the State Freshwater Wetlands program RIGL 2-1-20.1, 42-17.1, and 42-17.6, includes regulation of stormwater as it has the potential to divert or alter the functions and values of freshwater wetlands within the State. If there are wetlands on your site, you must first consult with the Freshwater Wetlands Permitting Program to determine if your project needs to comply with stormwater requirements.