Stormwater

It makes the world green, that’s the power of STEP

What is STEP?

The Stormwater Transformation and Enhancement Program (STEP) will bring a new life and a renewed utility to the High Line Canal as a green infrastructure system that provides for stormwater quality management. The High Line Canal Conservancy is working with Denver Water, Mile High Flood District and local jurisdictions through STEP to advance stormwater solutions in the Canal for both existing and new conditions. The main goals of STEP are to: 

  • Plan for and implement stormwater projects in the Canal to capture the benefits as green stormwater infrastructure. 
  • Implement a collaborative management, maintenance, financial and operational model to advance stormwater projects in the Canal. 

Benefits of STEP

Any drop of water that falls into adjacent watersheds naturally drains toward the Canal. In many areas, stormwater already enters the Canal, while in other areas, stormwater is diverted away from the Canal. Managing stormwater in the Canal can provide many benefits: 

  • WATER: Improves water quality, boosts water cycle support and upholds flood management 
  • ENVIRONMENT: Improves air quality, supports habitat and reduces the urban heat island effect 
  • COMMUNITY: Encourages healthy lifestyles, builds climate resilience and enhances user experience stewardship 

STORMWATER PROJECTS UNDERWAY

The Conservancy is working with our partners in the Canal Collaborative to help the Canal find new life as a green stormwater management system with multi-tiered benefits for our region’s water, environment, and communities. So far, 12 miles of the Canal have been formalized for stormwater management, with projects in Mirabelle Metro District, Douglas County, Littleton, Centennial, Greenwood Village, and Denver. 

  • Location: Solstice residential development to Plum Creek 
  • Length: 3 miles 
  • Status: Implemented in 2020 
  • Description: Solstice is a new residential development in Douglas County just south of Chatfield State Park. The developer has integrated the Canal into its stormwater system, treating stormwater before it reaches the Canal and pulling back the banks to allow for stormwater conveyance in the Canal channel. The developer is featuring the Canal at the center of the development, incorporating the Canal corridor into a 37-acre linear park that will expand the size of the open space on either side of the Canal. The developer has planted trees to reestablish vegetation in the area, leveraging the additional stormwater that will make its way to the Canal to enhance ecological health. Mirabelle Metro District is now responsible for managing this portion of the Canal while Douglas County will continue to maintain the trail. 
  • Location: Spring Gulch to Marcy Gulch 
  • Length: 1.5 miles 
  • Status: Implementation 
  • Description: Douglas County has signed a license agreement with Denver Water to formalize stormwater discharging from Santa Fe Drive into the Canal at Spring Gulch. As part of Douglas County and the Colorado Department of Transportation’s highway improvement project for Santa Fe Drive, an opportunity arose for the County to execute an agreement with Denver Water that formalizes the use of the Canal to convey existing stormwater from U.S. Highway 85. Stormwater runoff from the proposed highway improvement project will be pretreated before being discharged through an existing 72-inch storm sewer pipe that flows into the Canal. Douglas County will take responsibility for maintaining and managing this portion of Canal to ensure safe passage of stormwater.   
  • Location: Windemere Street to Lee Gulch 
  • Length: 1 mile 
  • Status: Implemented in 2020 
  • Description: The City of Littleton implemented its first stormwater project in the High Line Canal, allowing for a new outfall of stormwater that will flow from Windermere Street before it is released into the natural waterway at Lee Gulch. As a part of this project, the City of Littleton has taken over maintenance and management of the Canal in this section while South Suburban Parks and Recreation will continue to maintain the trail. 
  • Location: Marion Street to Big Dry Creek 
  • Length: 1.5 miles 
  • Status: Implemented 2021 
  • Description: As part of the Franklin Elementary School redevelopment project, stormwater is now being discharged through an existing outfall at Franklin Street. As this project is in Centennial, the Southeast Metro Stormwater Authority (SEMSWA) will take over management and maintenance of the channel. SEMSWA’s project extends from Marion Street to the Big Dry Creek waste gate located at the southern end of deKoevend Park. South Suburban Parks and Recreation will continue to maintain the trail. 
  • Location: Orchard Road (west of University) to Little Dry Creek 
  • Length: 2.5 miles 
  • Status: Implemented in 2019 
  • Description: Greenwood Village has formalized stormwater that reaches the High Line Canal across 2.5 miles from Orchard Road to the jurisdictional boundary just east of Steele Street. Greenwood Village now maintains the Canal and the trail through this area. 
  • Location: Hampden Ave to I-25 
  • Length: 2 miles 
  • Status: Implemented in 2021 
  • Description: The Denver Department of Transportation and Infrastructure implemented an innovative stormwater project along the Canal from Hampden Ave to I-25, including along Eisenhower Park and Wellshire Golf Course. The project includes three water quality berms in the Canal to improve water quality, four forebays to clean water before it reaches the Canal and two water quality vaults to remove trash and sediment. 

Stormwater FAQs

Stormwater is precipitation that runs off impervious surfaces, such as driveways, parking lots or rooftops, and flows into storm drains and eventually into our waterways.

Stormwater either filtrates through pervious or permeable, natural surfaces such as soil or grass, or runs off impervious or hard surfaces such as driveways, sidewalks and streets and escapes natural cleansing by plants and soil. If stormwater hits wetlands, forests and grasslands, these natural resources can hold excess water in place, filtering out sediment and pollutants before they reach waterways.

Stormwater runoff is a significant cause of environmental degradation of our waterways. As stormwater drains toward waterways, it can pick up contaminants, polluting the runoff that may cause harmful effects on water supplies, recreation areas, fisheries and wildlife. Managing stormwater with green infrastructure can significantly reduce these negative effects, while also decreasing the risk of flooding.

As the Denver metro area continues to urbanize with more impervious surfaces, stormwater runoff will only increase, leading to higher chances of urban flooding and decreased water quality.

Stormwater Impervious Graphs

Green infrastructure is a sustainable, cost-effective resilient approach to managing wet and dry weather impacts by mimicking the natural environment to slow down stormwater runoff. It relies on the use of vegetation, soils, roots and natural processes to manage stormwater, improve water quality and provides a host of other environmental, social and economic benefits.

Green infrastructure helps to minimize the amount of unmanaged stormwater going into our natural waterways and comes in a variety of sizes ranging from large-scale naturally occurring systems like forests and floodplains to smaller, engineered systems built to mimic these larger systems, including stormwater planters, bioretention/rain gardens.

Types that will be used in the High Line Canal include:

Stormwater Berms and Detention Facilities

Support for STEP is provided by a grant from the Pisces Foundation, which seeks ways to accelerate to a world where people and nature thrive together. The program has also been supported by the JPB Foundation through the Funders’ Network for Smart Growth and Livable Communities, an administrative partner in issuing and managing this grant.

Partnerships supporting this work include Stormwater Permittees for Local Awareness of Stream Health (SPLASH) and the Stormwater Technical Advisory Committee (STAC).

SPLASH is located in the Arapahoe County area. Members work together to educate the public about ways to reduce the pollution that may make it into local bodies of water. Learn more about SPLASH.

As part of the Canal Collaborative, STAC is comprised of jurisdictional stormwater managers and engineers along with Denver Water and Mile High Flood District representatives met every other month to provide technical expertise and direction on using the Canal for stormwater management as a One Water system. For more information on the Canal Collaborative, click here.

The Conservancy completed work with EPA’s Offices of Wastewater Management and Community Revitalization. EPA’s AAA method incorporates community priorities with technical evaluations to find affordable and effective One Water solutions. Over the course of a year, the Conservancy gathered community input on priorities and used those priorities to determine goals, objectives and metrics in collaboration with the STEP technical leadership team to quantify the multiple benefits of repurposing the Canal as green stormwater infrastructure. This 10-step process culminated in a cost benefits analysis that applied different alternatives for treating stormwater in the Canal.

We are pleased to announce the completion of the stacked benefits analysis for the High Line Canal in collaboration with our jurisdictional partners and with financial support from the Pisces Foundation and The Funder’s Network.

The High Line Canal Conservancy (HLCC) and its partners, including Denver Water, Mile High Flood District (MHFD) and the 11 adjacent jurisdictions, are creating a 71‐mile linear park‐like feature in the Denver metropolitan area with a primary focus on transforming the former irrigation canal into a regional stormwater management structure and enhanced public green space. In 2018, these partners established STEP with the overarching goal to:

Continue to plan for and implement a transformation of the Canal into an inspiring model utilizing smart water planning that demonstrates the benefits of integrated stormwater and urban watershed management for the ecological, physical and social health of our community while protecting precious freshwater resources for our rivers and streams.

Program objectives include working on a range of green stormwater infrastructure issues such as finance models, maintenance plans, and education and leadership development along with an objective to specifically support “the identification, advancement, and enlargement of a pipeline of stormwater projects that will demonstrate the benefits of smart water approaches for managing stormwater in the HLC.” Click here to read the full technical memo.

Community input is more important than ever as the Conservancy focuses on implementing critical project across all 71 miles. Get involved!

Together, we are making strides towards preserving, protecting and enhancing the Canal. Learn more!