High Line Canal Stormwater Quality Pilot Project

The Week Ahead: November 29, 2021

Denver’s Department of Transportation and Infrastructure (DOTI) has begun construction of The High Line Canal Stormwater Quality Pilot Project in southeast Denver. DOTI’s project is one of five stormwater quality efforts in and along the High Line Canal, with additional projects underway in Littleton, Centennial, Greenwood Village and Douglas County. The Canal was originally built to convey irrigation water but is no longer used for that purpose. The green infrastructure initiative is intended to transform the Canal into a stormwater management system, once again bringing some water to the Canal, thereby extending the life of the existing tree canopy and providing much needed water for new plantings and wildlife.

Please keep in mind that the work is taking place in and adjacent to an active waterway. Plans, schedules and completion dates are subject to change due to weather, water levels and other factors.

Progress Update:

  • Crews have completed the installation of the underground stormwater quality vaults (“Carlsonators”) on E. Eastman Avenue at S. Glencoe Street and on S. Holly Street just north of E. Eastman Avenue.  All access is now restored.
  • Crews completed the S. Holly Bridge and it is now open for pedestrians.
  • The Forest Street Bridge is also complete and open for pedestrian use.
  • Construction of the stormwater quality structure in the Canal at S. Dahlia Street and at Wellshire Golf Course are largely complete, with minor landscape restoration remaining.
  • Landscape restoration on the S. Ash Street, S. Bellaire Street, S. Dexter Street and S. Forest Street drive-through forebays is ongoing (water quality feature adjacent to the Canal).During this time, on-street parking remains restricted, and construction equipment remains in place.  The pedestrian bridges at Bellaire Street and Forest Street are open, please use caution as crews complete their restoration work.

How to get regular construction updates:


Crews installing the replacement bridge at S. Holly Street over the High Line Canal on August 6.

Crews installing the replacement bridge at S. Holly Street over the High Line Canal on August 6.


Project Overview

In February 2021, Denver’s Department of Transportation and Infrastructure (DOTI) began construction of a stormwater quality pilot project at the High Line Canal in southeast Denver. The approximately one-mile long project includes installation of three stormwater quality structures in the Canal to clean and hold stormwater for slow release over an extended period of time.

The project also includes installation of two underground trash vaults, as well as four locations where slotted curbs ("forebays") and grass swales will be installed at existing storm outfalls on the south side of the Canal to provide for increased quality of stormwater flowing into the Canal.

Construction began at Wellshire Golf Course and will proceed east in Mamie D. Eisenhower Park culminating at the Interstate 25 underpass.  Please note that as the High Line Canal Stormwater Quality Structure construction project gets underway, the work is taking place in an active waterway. Plans, schedules and completion dates are subject to change due to weather, water levels and other factors. The latest construction information will be posted on this project webpage.

The City is undertaking the High Line Canal stormwater quality project as part of an annual water quality program aimed at meeting and/or exceeding regulatory requirements to provide water quality within the City and County of Denver.  

Access to the Canal trail will be restricted along short distances while the water quality features are built. Please follow and adhere to all directional signage during construction.

On account of their proximity to the High Line Canal, two bridge projects were rolled into the stormwater quality pilot project. The S. Holly Street bridge over the Canal will be replaced with a new bridge following structural damage caused by a felled tree. Additionally, following the reopening of the S. Holly Street bridge, the pedestrian bridge at S. Forest Street and the Canal will be closed to undergo deck/plank repair.

The High Line Canal Stormwater Quality pilot project and related bridge projects are expected to wrap-up in the Fall of 2021.

Construction Timeline

Please Note: As the High Line Canal Stormwater Quality Structure construction project gets underway, please keep in mind that the work is taking place in an active waterway. Plans, schedules and completion dates are subject to change due to weather, water levels and other factors.  The latest construction information will be posted on this project webpage. 

Wellshire Golf Course

Anticipated completion: late June 2021

  • Construction of Water Quality Structure in the High Line Canal just west of S. Colorado Boulevard, adjacent to the 9th hole.

S. Ash Street at High Line Canal dead-end

Anticipated completion: late June 2021

  • Street and sidewalk reconstruction (“drive-through forebay”) to filter out debris and clean stormwater prior to release into the Canal.

High Line Canal immediately west of S. Dahlia Street

Anticipated construction start: late June 2021

  • Construction of  Water Quality Structure in the Canal just west of S. Dahlia Street.
  • High Line Canal trail will be closed from S. Dahlia Street to just east of the S. Bellaire Street bridge.
  • A detour is in place directing bicyclists to proceed south on S. Dahlia Street, then west on E. Eastman Avenue in the designated bike lane on the north side of E. Eastman between S. Dahlia Street and S. Colorado Boulevard.
  • Denver Parks and Recreation will perform trail repairs while the trail is closed for installation of the Dahlia Water Quality Structure.

S. Bellaire Street at High Line Canal dead-end

Anticipated completion: late June/early July 2021 

  • Street and sidewalk reconstruction (“drive-through forebay”) to filter out debris and clean stormwater prior to release into the Canal.
  • The pedestrian bridge over the High Line Canal connecting S. Bellaire Street to the Canal trail has been reopened. Please use caution when using the sidewalk to access the bridge, as crews are completing restoration work in the S. Bellaire cul-de-sac. 

S. Dexter Street at High Line Canal dead-end

Anticipated completion: late June/early July 2021

  • Street and sidewalk reconstruction (“drive-through forebay”) to filter out debris and clean stormwater prior to release into the Canal. 

High Line Canal at I-25 between S. Grape Way and S. Holly Street

Anticipated construction start: early July 2021

  • Construction of Water Quality Structure in the Canal.
  • Bicycle access will be maintained; however cyclists may be directed to dismount in the construction area.

E. Eastman Avenue and S. Glencoe Street Intersection

Anticipated construction start: early July 2021

  • Installation of underground water quality vault in storm sewer system that removes debris and sediment prior to canal release.
  • Intersection will be closed to through traffic for approximately 4 to 5 weeks.
  • Work will require intermittent water disruptions. Impacted property owners will be notified in advance. 

S. Forest Street and High Line Canal Dead-end/Bridge Repair

Anticipated completion: mid-July 2021

  • Street and sidewalk reconstruction (“drive-through forebay”) to filter out debris and clean stormwater prior to release into the Canal.
  • Pedestrian bridge over High Line Canal connecting S. Forest Street to High Line Canal trail will remain accessible during this phase of construction.
  • Bridge will be closed to undergo deck/plank repair after the Holly Street bridge is replaced and opened to pedestrians (see below).

S. Holly Street Bridge Replacement over High Line Canal

Anticipated demolition/bridge removal start: mid-July 2021
Anticipated new bridge installation start: early August 2021
Anticipated completion: late August/early September 

  • Removal of existing damaged bridge.
  • Installation of new bridge to replace damaged bridge. 

S. Holly Street between E. Eastman Avenue and the High Line Canal

Anticipated construction start: mid-July 2021

  • Installation of underground water quality vault in storm sewer system that removes debris and sediment prior to canal release.
  • Traffic on South Holly Street adjacent to construction will be reduced and narrowed for access heading north.

Project Map

Map of work locations for High Line Canal Water Quality project in Southeast Denver

Frequently Asked Questions

What is the High Line Canal Stormwater Quality Pilot Project?

The High Line Canal Stormwater Quality Pilot Project is a groundbreaking “green infrastructure” project undertaken by the City of Denver’s Department of Transportation and Infrastructure (DOTI) in collaboration with the High Line Canal Conservancy, the Mile High Flood Control District and Denver Water. The approximately one-mile long stormwater management project includes installation of three stormwater quality structures in the Canal to clean and hold stormwater for slow release over an extended period of time.

The project also includes installation of two underground stormwater vaults to remove trash and sediment as well as four locations where slotted curbs (“forebays”) and grass swales will be installed at existing storm outfalls on the south side of the Canal to help clean stormwater flowing into the Canal.

What is the timeline for this project?

Construction has begun at Wellshire Golf Course and will proceed east in Mamie D. Eisenhower Park culminating at the Interstate 25 underpass. The construction timeline is posted on the project webpage (denvergov.org/DOTIprojects). Please keep in mind that the High Line Canal Stormwater Quality pilot project construction is taking place in an active waterway. Plans, schedules and completion dates are subject to change due to weather, water levels and other factors. The project is currently scheduled to take approximately 7-9 months to complete.

What will the stormwater quality structures in the High Line Canal look like?

The stormwater quality structures in the Canal consist of a partially buried concrete wall with surrounding boulders, a 24”x 40” weir plate, and an 18”x 24” aluminum slide gate, giving the structure both function and aesthetics.  The Canal structures at Wellshire Golf Course and S. Holly Street will have an additional 7’ wall made of pressure treated wood logs. These structures were designed to resemble historical water management devices that once occupied the Canal. Illustrations of the various stormwater quality structures are included on the project website.

What is a forebay?

A forebay is a slotted curb that slows and cleans stormwater as it flows from the street and into the Canal.  Holes in the street curb allow stormwater to pass though, and the stormwater ponding at the curb forces solids to settle in the gutter rather than entering the Canal.  Street-sweeping trucks can drive through the gutter and sweep up the dirt and solids.  Behind the curb, stormwater passes through a swale (a grassy, permeable zone) that further cleans stormwater before spilling into the Canal.

Will access to the High Line Canal be impacted during construction?

Access to and along the High Line Canal trail will be restricted along short distances while the water quality features are built in the Canal west of S. Dahlia Street and east of S. Holly Street. During construction of the S. Dahlia structure, a trail detour will be in place from S. Dahlia Street and Eisenhower Park to S. Colorado Boulevard via E. Eastman Avenue. Signage will be in place in advance of the closure to alert trail users, and details about the closure will be posted on the project web page and included in email updates.

Additionally, bridge closures will be required for approximately six weeks at S. Bellaire Street and at S. Forest Street on the south side of the Canal while crews install each forebay. The bridges will not be closed at the same time. As construction involves the use of heavy equipment, please follow and adhere to all directional signage and safety protocols during construction.

Will any trees be removed in connection with this project?

Construction crews will clear limited sections of shrubs, vegetation, volunteer shoots, and small invasive trees in Denver Water property in order to access the Canal during construction. At this time, no privately owned trees have been identified for removal, and only one City-owned tree may need to be removed for construction at S. Forest Street.

What hours will crews be working?

Construction will occur generally from 7 a.m. to 5 p.m. on weekdays. Saturday work may occasionally be required, between the hours of 8 a.m. and 5 p.m.

How can residents stay informed about the progress of the project?

DOTI has created a webpage devoted specifically to this project, and construction updates will be posted regularly. Visit www.denvergov.org/DOTIprojects, scroll down to "Storm/Sanitary Sewer Infrastructure" and click on "High Line Canal Stormwater Quality".

To sign up and receive emailed project updates, please send a request to ccd.constructionupdates@gmail.com.

How can residents contact the project team?