Storm Water System


Stormwater runoff is a major cause of water pollution in urban areas. When rain falls on our roofs, streets, and parking lots in cities and their suburbs, the water cannot soak into the ground as it should. Stormwater drains through gutters, storm sewers, and other engineered collection systems and is discharged into nearby water bodies. The stormwater runoff carries trash, bacteria, heavy metals, and other pollutants from the urban landscape into those water bodies. Today cities and urban areas regulate storm water systems to help improve water quality by using various methods to remove pollutants from storm water before it enters our water bodies. These methods include Best Management Practices, Low Impact Development and Green Infrastructure.

Due to the size of the City of Helena, our storm water system is regulated under the Montana Pollution Discharge Elimination System General Permit for Storm Water Discharges Associated with Small Municipal Separate Storm Sewer Systems (General Permit(PDF, 457KB) and Notice of Intent(PDF, 6MB) )issued by Montana Department of Environmental Quality. The City has developed a Storm Water Management Program(PDF, 438KB) in accordance with the General Permit requirements. New additions of infrastructure to the system and new connections that will discharge to the storm sewer system must be developed to meet the requirements in the General Permit, the Storm Water Ordinance under City Code 6-6-1, the Engineering and Design Standards, and the system must be operated to apply Best Management Practices to protect storm water quality.

The Utility Maintenance Division maintains and operates the storm sewer system. The storm sewer system consists of approximately:

  • 70 miles of storm pipe, which range from 8 inch to 90 inch pipes
  • 30 miles of open storm drainage channels
  • 700 manholes
  • 1,800 storm inlets

If you see any maintenance needs, such as clogged inlets, eroding channels or poor drainage, please report them to: Utility Maintenance Division at 447-8567 or the Engineering Division at 447-8431.

Storm Water Management Program

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 General Permit for Storm Water Discharges Associated with Small Municipal Separate Storm Sewer Systems 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 Municipal Separate Storm Sewer System (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 Storm Water Management Program is available here(PDF, 26MB) . The public is encouraged to review the SWMP. The mechanism for providing public input for the SWMP during the active request for input is the City’s Be Heard Helena web page. The City posts a request for comments, questions, and complaints on the current SWMP during the last quarter of each year. A link to the appropriate Be Heard Helena page will appear on this webpage during active requests for input. If you have comments, questions, or complaints outside of the request for input, please contact the City of Helena’s Engineering Division at (406) 447-8096.

Each year, the City of Helena prepares a Storm Water Small MS4 Annual Report which is submitted to the Department of Environmental Quality. Last year’s annual report may be accessed at the following link: Small MS4 Annual Report(PDF, 48MB).

2018 Small MS4 Annual Report(PDF, 25MB)
2019 Small MS4 Annual Report(PDF, 16MB)
2020 Small MS4 Annual Report(PDF, 18MB)
2021 Small MS4 Annual Report(PDF, 17MB)

(PDF, 17MB)2022 Small MS4 Annual Report(PDF, 48MB)

The City of Helena also partners with the Lewis and Clark County Water Protection District (District). The District was formed in 1992. Its mission is to preserve, protect and improve water quality within District boundaries which includes the City of Helena and the Lake Helena Watershed. The District also provides outreach and education opportunities to the public. More information can be found at the Lewis and Clark County Water Quality Protection website:

For additional information related to storm water protection at home and to see how you can take part, please see our Storm Water Runoff Pollution(PDF, 3MB) and Clean Water Begins at Home(PDF, 1MB) flyers.

Illicit Discharge

In general, only stormwater and water from the City water distribution system are allowed to be discharged into the storm drainage system. Illicit discharges are discharges to storm drains during dry weather that contains pollutants and/or pathogens and any discharge to the storm sewer system that is not composed entirely of storm water, with exceptions for discharges allowed under the General Permit, for example: waters for firefighting operations. The Environmental Protection Agency’s, Storm Water Phase II Final Rule for Illicit Discharge Detection and Elimination Minimum Control Measure can be found here: IDDE Rule(PDF, 275KB).

Illicit discharges in the City of Helena are most likely to result from home car care, household hazardous waste disposal, lawn and garden care, pet waste, carpet cleaning/restoration companies, the construction industry, gas stations, industrial facilities and operations, landscapers, mobile cleaning and pressure washing, post construction facility owners, and restaurants and food trucks.

How to Report an Illicit Discharge:

If you observe or suspect illicit discharging or dumping of pollutants into the stormwater system has occurred, please report it immediately to the City of Helena’s Engineering Division at (406) 447-8431. You can also report a discharge or submit a complaint online from the City's My Helena App. Instructions for online submissions are located here(PDF, 1MB).

Low Impact Development and Green Infrastructure

The term Low Impact Development (LID) refers to systems and practices that use or mimic natural processes that result in the infiltration, evapotranspiration or use of stormwater in order to protect water quality and associated aquatic habitat. Green infrastructure (GI) is the patchwork of natural areas that provide habitat, flood protection and cleaner water. At both the site and regional scale, LID/GI practices aim to preserve, restore and create green space using soils, vegetation, and rainwater harvest techniques. LID is an approach to land development (or re-development) that works with nature to manage stormwater as close to its source as possible. LID employs principles such as preserving and recreating natural landscape features, minimizing effective imperviousness to create functional and appealing site drainage that treat stormwater as a resource rather than a waste product. There are many practices that have been used to adhere to these principles such as bioretention facilities, rain gardens, vegetated rooftops, rain barrels, bioswales and water quality ponds. By implementing LID principles and practices, water can be managed in a way that reduces the impact of development and promotes the natural movement of water within an ecosystem or watershed. Applied on a broad scale, LID can maintain or restore a watershed's hydrologic and ecological functions.

The City of Helena, as part of an MS4 working group and in cooperation with the Montana Department of Environmental Quality, has prepared the Montana Post-Construction Storm Water Best Management Practices Design Guidance Manual (BMP Manual)(PDF, 13MB). These best management practices identified in the BMP Manual represent green infrastructure that can be applied individually or in combination to a development or redevelopment to provide a LID system. 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.

Rain Gardens

The City of Helena encourages property owners to use Rain Gardens wherever possible to improve water quality and your property. The City of Helena has prepared the following Rain Garden flyer(PDF, 8MB) related to design and construction of Rain Gardens in the Helena area.

Construction Storm Water

Permittee Requirements for Construction Activities:

An owner or operator of a construction activity is required to obtain authorization under the General Permit for Stormwater Discharges Associated with Construction Activity for construction activities that include clearing, excavating, grading, grubbing, or placement/removal of earth material with a total area of one or more acres or is part of a larger common plan of development. An owner or operator is a person who owns, leases, operates, controls, or supervises the construction activity. To apply for an authorization under the General Permit within the City of Helena submit a complete Notice of Intent Application Package including Storm Water Pollution Prevention Plan forms to the Building Department with your building permit application and to DEQ.

Click Here to View DEQs Storm Water Management during Construction Brochure(PDF, 6MB).

For additional information please see our Storm Water and Construction Flyer(PDF, 1MB).

How to Submit Construction Activity Related Complaints:

If you observe or suspect illicit discharging or dumping of pollutants into the stormwater system from construction activity, please report it immediately to the City of Helena Engineering Division at (406) 447-8431. You can also report a discharge or submit a complaint online via the My Helena App. Instructions for online submissions are located here(PDF, 1MB).

Education, Outreach, and Events

Upcoming Events:

- Mayor's Water Challenge

Helena Mayor Wilmot Collins is joining mayors across the country asking residents to make a commitment to reduce pollution and manage water resources more wisely. To participate in the challenge, residents can go online and make pledges to conserve water, reduce pollution, and save energy. 

April 1- April 30, 2023

Click Here to Learn More

- Annual Spring Latex Paint Exchange

The City of Helena Recycling office will host a Latex Paint exchange at the Transfer Station in the month of April. Anyone participating in the event must be a residential permit holder. Paint from businesses or commercial haulers will not be accepted. 

Dates: Drop Off- April 14-21, 2023                Pick Up- April 23-29, 2023

Click Here to Learn More 

Past Events:

-Annual Household Hazardous Waste Collection and Disposal Day

October 1, 2022        9am to 2pm       Batch Fields, 2101 N Benton Avenue           Click Here to View Event Flyer(PDF, 132KB)  

-Annual Fall Latex Paint Exchange

Dates: Drop Off- September 23 through October 30, 2022      Pick Up- October 11-14, 2022

-Lake Helena Watershed Festival

The 2022 Lake Helena Watershed Festival's theme is "Recharge" to energize the festival's return after two years. Learn about water quality conservation methods, participate in fun activities and demonstrations, and celebrate your local watershed. 

August 27, 2022           Women's Park, 500 Fuller Avenue

Click Here to Learn More


Outreach Strategy Information & Materials

View the City's Outreach Strategy Here(PDF, 427KB)