Storm Water Program Overview

Storm Drain Image

Federal regulations require municipalities and other operators of storm water systems to obtain authorization to discharge storm water under the National Pollution Discharge Elimination System.  Due to Helena's size, we are required to obtain authorization to discharge storm water as a Phase II community (See EPA Storm Water Phase II Final Rule, Fact Sheet 1.0.)

The Municipal Separate Storm Sewer System (MS4) General Permit requires permittees to develop, implement, and enforce a Stormwater Management Program (SWMP). The SWMP is designed to reduce the discharge of pollutants from the permitted MS4 to the Maximum Extent Practicable (MEP), to protect water quality, and satisfy the appropriate water quality requirements of the Montana Water Quality Act.

The Storm Water Management Program consists of Best Management Practices (BMPs) for each of the six Minimum Control Measures (MCMs) as identified in the Permit:
Public Education and Outreach

  • Public Participation and Involvement
  • Illicit Discharge Detection and Elimination
  • Construction Site Storm Water Runoff Control
  • Post Construction Storm Water Management for New Development and Redevelopment
  • Pollution Prevention/Good Housekeeping for Municipal Operations

The City of Helena, as part of a MS4 working group and in cooperation with the Montana Department of Environmental Quality, a Montana Post-Construction Storm Water BMP Design Guidance Manual (BMP Manual) has been prepared.  Click this link to access the BMP Manual. The BMP Manual provides design guidance for achieving the storm water quality requirement in the Engineering and Design Standards for treatment of runoff from the 0.5 inch precipitation event.  Click this link to access the Engineering and Design Standards.

EPA Storm Water Fact Sheets

Lewis and Clark County Storm Water Information

To report illicit discharges and other stormwater issues, please contact:

Matt Culpo - Stormwater Engineer
(406) 447-8073