Stormwater Projects

Stormwater projects can include dry well installation, maintenance, and cleaning; levee maintenance; and various other projects that address how stormwater makes its way through Missoula. Below are projects scheduled for or continuing into 2024.

Levee Maintenance Work—North Riverside Trail ClosureLevee _Detour Maps_Page_2
March 4 – 8, 2024

The City’s Stormwater Utility will begin routine vegetation maintenance on two Clark Fork River levees on Monday, March 4, with completion expected by Friday, March 8, weather dependent. Portions of the North Riverfront Trail system will be closed from 9 a.m. to 4 p.m. weekdays. Work will start at the Madison Street Bridge and move west to the Orange Street Bridge and then crews will begin work between the California Street pedestrian bridge and Russell Street.

Trail closure details:Levee _Detour Maps_Page_1

  • Trail closures are timed to avoid peak commuter traffic times, but trail users should plan for a few extra minutes of travel time during the project.
  • For the trail section between the Madison Street and Orange Street bridges, a prearranged detour route has not been defined due to winter road conditions and other factors. Cyclists and pedestrians are advised to use parks, streets, and sidewalks as needed to travel around the trail closures.
  • The portion of the trail between the California Street pedestrian bridge and Russell Street bridge will be detoured to nearby Cedar and California streets while crews complete the vegetation removal work. The pedestrian bridge and the trail east of the pedestrian bridge will both remain fully open to trail users.

The U.S Army Corps of Engineers requires vegetation maintenance to preserve levee structures. This includes removal of trees with trunks larger than 4 inches and non-native trees and shrubs on the levees. To comply with Army Corps regulations that require removal of all trees within 15 feet of either side of the floodwall and levee structures, some trees in the adjacent park areas and along the floodwall must be removed. Missoula Parks and Recreation staff will plant replacement trees in areas that don’t encroach on the levee boundaries.

Stormwater utility staff collaborated with Missoula Parks and Recreation staff to identify the non-native vegetation that will be removed from the levees. They also consulted with Montana Fish, Wildlife, and Parks to obtain the necessary permit. The Clark Fork River will not be disturbed during this work.

Engineers from the Army Corps inspect the levees annually to ensure the levees are properly constructed and maintained, which is critical for the homes and businesses protected by the levees to prevent flooding. If the levee system is not maintained at an acceptable level, it could lose accreditation, causing all businesses and residences protected by the levees to either obtain or increase their flood insurance coverage.

Bitterroot Outfall Project

Location:  On the Bitterroot River just south of the Highway 93 bridge.

Description:  The project will include improvements to the outfall area to address Bitterroot River water quality impairment from stormwater flow from Pattee Creek. Sediment from the swale area is deposited in the river.

  • Best Management Practices (BMPs) to address heavy loads of sediment that reach this outfall. The source of sediment is primarily due to road sanding operations in the South Hills during the winter. BMPs could include a hydrodynamic separator installed upstream of the outfall or a sediment forebay that enables sediment removal in a designated location. To facilitate maintenance of this type of BMP, a bypass channel or pipe would be installed.
  • Clearing sediment from the energy dissipaters so that they are fully exposed.
  • Removal of trees and vegetation that is encroaching on the facilities before damage occurs. 
  • Re-grading or otherwise modifying the swale so that flow meanders through and accumulated sediment can settle out.
  • Additional vegetation to provide enhanced nutrient uptake and sediment deposition.
  • Upgrading the undersized culvert crossing located downstream of the flap gate to accommodate the 1% annual chance flood event.

Benefits:  Improved water quality in the Bitterroot River by improving infrastructure so that sediment is better filtered and settled out of the stormwater before it reaches the river. Planting and installing better green infrastructure helps remove nutrients from the stormwater as well.

Project Dates:  Construction is anticipated in 2025. This page will be updated as further information becomes available.

Public Meeting:  A public meeting was held on July 12, 2023. Link to Bitterroot Outfall meeting recording

Area Map—coming soon

Project Contact:  Adam Marsh, Utility Engineer, at MarshA@ci.missoula.mt.us or 406-552-8835

Completed Stormwater Projects

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