DEP’s stormwater laws and regulations work toward protecting and restoring surface water and groundwater impacted by stormwater flows. Stormwater runoff from developed areas carries pollutants, and affects the rates and volumes of flows in natural waterbodies in ways that can cause damage. Everyone has a role in reducing impacts from stormwater runoff, from the large developer constructing a new parking lot, to the homeowner using good erosion control methods and handling chemicals carefully around the house.

DEP regulates a variety of stormwater programs under three core laws:

  • Site Location of Development Law (Site Law). This law relates to larger commercial and residential developments in Maine, in general, projects that create more than 3 acres of new impervious area (like buildings and parking lots), or occupy more than 20 acres of land (like golf courses and ski areas). The Site Law reviews several environmental standards, including potential stormwater impacts from proposed developments.
  • Stormwater Management Law. Maine’s Stormwater Management Law lists stormwater standards for projects that propose more than one acre of disturbed area. Disturbed area generally includes areas that are stripped, graded, excavated, or filled during construction. The Stormwater Management Law includes standards for both the quantity of stormwater runoff, as well as the quality of that runoff.
  • Waste Discharge Law. A waste discharge license is required for the discharge of pollutants to Maine’s environment. There are a number of general permits that the DEP administers, including the Multi-Sector General Permit, the Municipal Separate Storm Sewer Systems (MS4) General Permit, and the Maine Construction General Permit, that cover a wide variety of activities.

Additional information about the laws, rules, application forms and other materials is available at the three links above.

Chapter 500 Stormwater Management Updates Stakeholder Engagement Process


Have a question or need more information? Use the links below to find out more or connect with DEP staff.


Most Land Bureau inquiries can be made using one of the fillable forms above.  Submitting the online form ensures that your inquiry, complaint or request for information will be viewed and responded to as soon as possible by a Bureau staff person. Because of the high volume of inquiries, it may take several days for you to receive a response or follow up.