Stormwater program rulemaking

The U.S. Environmental Protection Agency (EPA) is the federal agency that implements the Clean Water Act (CWA). To regulate discharges to water under the CWA, the EPA created the National Pollutant Discharge Elimination System (NPDES) permit program. The EPA delegated the program to Minnesota for the state to carry out through the Minnesota Pollution Control Agency (MPCA). The MPCA has control of the permitting, administrative, and enforcement aspects of the program.

The NPDES permit program has many program areas, including Stormwater. The Stormwater Program area is relatively new and still evolving. As federal requirements change, Minnesota must update state statutes, rules, and permits to be as stringent as the new federal regulations and follow schedules identified in the regulations.

Recent federal changes include the 2009 EPA Construction and Development Effluent Guidelines and 2016 EPA Remand Rule that improves the MS4 permitting public process. State changes include the MPCA’s 2010 update to the Clean Water State Revolving Fund that provides financial assistance for wastewater and stormwater infrastructure. The MPCA also revised Minnesota Rules Chapter 7077 in 2013 and 2014 to address the point system that determines funding for stormwater projects. See the Wastewater and Stormwater Financial Assistance webpage for information. In addition, the non-degradation rule was adopted in 2016.

Stormwater permit rule

Rule-related link


Statues governing stormwater rules

Federal stormwater regulations


The EPA developed the federal Stormwater Program regulations, which are part of the NPDES permit program, in two phases - Phase I and Phase II. The Phase I regulations, issued in 1990, require a NPDES stormwater discharge permit from:

  1. eleven regulated industrial activity categories, including construction activity that disturbs five or more acres of land; and
  2. municipal separate storm sewer systems (MS4s) serving populations of 100,000 or more.

Building off Phase I, the EPA issued Phase II regulations in 1999. These regulations expanded the scope of the NPDES Stormwater Program to include smaller MS4s in urbanized areas, construction activities that disturb between one and five acres of land, and smaller municipally owned industrial activities. In addition, the Phase II federal regulations revised the conditional no-exposure exclusion for industrial activities.

In response to the new federal regulations, the MPCA published the Phase I Stormwater Program rules in 1994 and 1995 and Phase II Stormwater Program rules in 2005.

Minnesota Rule description

Phase I and Phase II Stormwater Program rules are described in Minnesota Rules Chapter 7090. The rules detail the NPDES stormwater permit requirements for regulated MS4s and construction and industrial activities. A brief description of the rules by Stormwater Regulatory Program are provided below.

Municipal program

Minnesota Rules Chapter 7090 requires all federally regulated and MPCA delegated small MS4s to have a NPDES permit. Phase I regulations required two MS4s to have NPDES permit coverage, followed by approximately 200 under Phase II regulations.

MS4 designation process and criteria

Minnesota Rules Chapter 7090 establishes criteria and a process to designate MS4s for permit coverage. The rule designates small MS4s located outside of the urbanized area. This includes municipalities with a population of 10,000 or more or a population of 5,000 to 10,000 that currently or may discharge to a special or impaired water. The rule also designates partial MS4s (cities and townships) that are in part located within an urbanized area. Under the rule, owners of MS4s are required to get permit coverage within 18 months of designation.

Permitting these MS4s better protects high quality and impaired waters while allowing densely populated and rapidly growing communities to have more foresight when planning for development.

See Stormwater Program for Municipal Separate Storm Sewer Systems (MS4)

Construction program

For the construction program, Minnesota Rules Chapter 7090 establishes the permit requirements for small construction activity. This includes clearing, grading, and/or excavating that disturbs between one and five acres of land. Construction activity also includes the disturbance of less than one acre of total land area that is part of a larger common plan of development or sale if the larger common plan will ultimately disturb one or more acres.

The rule provides for a notification by the MPCA of construction stormwater permit coverage for certain emergency and feedlot construction activities. These projects would be covered by the NPDES/State Discharge System (SDS) construction stormwater general permit without submittal of a permit application, if specific eligibility criteria are met. See Stormwater Program for Construction Activity.

Industrial program

The permit requirements for industrial activity are also in Minnesota Rules Chapter 7090.

The rule sets the conditional exclusion from permitting for no-exposure of industrial activities. This allows facilities that meet specific eligibility criteria to certify a condition of no-exposure instead of obtaining a NPDES/SDS Industrial Stormwater Multi Sector General Permit. Under Phase II, the no-exposure exclusion applies to all regulated categories of industrial activity listed in the Phase I regulations, except construction activity. See Stormwater Program for Industrial Activity.

Rule-related documents