South Platte River Restoration

The South Platte River represents a vital habitat corridor that links the Rocky Mountains to Colorado’s Eastern Plains.  Flowing through the heart of downtown Denver, the South Platte has been impacted by a history of industry and development.  To envision a better future for the river with improved ecosystem functions, the City and County of Denver, U.S. Army Corps of Engineers, The Greenway Foundation, and the Mile High Flood District developed a concept plan to restore a six-mile stretch of the South Platte River, known as the Urban Waterways Restoration Study (UWR).

Birch Ecology is an integral part of the team completing the first phase of the South Platte River Restoration – an evolution, final design, and implementation of the habitat restoration that was envisioned in the UWR.  This important public benefit project is being generously sponsored by Revesco Properties, developers of The River Mile – an ambitious project aiming to rediscover the river as a cultural, recreational, and ecological amenity and focal point for the community.   The re-designed river corridor will help to revitalize this part of downtown Denver in conjunction with with The River Mile development.

The project area, known as “Reach 5,” extends from Confluence Park upstream for 1.3 miles, above I-25 and Colfax to the confluence with Lakewood Gulch.  The project includes in-stream and riparian habitat restoration, floodplain mitigation, and recreational improvements. It includes a re-design of the iconic Confluence Park and removal of the 7-foot-high dam, along with decades of accumulated sediments that have backed up behind the dam, which have impaired river function.  This will not only improve fish passage and habitat connectivity, it will facilitate construction of a restored, multi-stage channel that will safely convey the 100-year flood.   A healthier and more diverse stream bed will provide better habitat for fish – with cooler, deeper water during low flows, clean gravels, and better habitat for aquatic insect prey, known as macroinvertebrates.  Re-designed stormwater outfalls will be routed through aesthetic wetland creations to clean and filter the water before it reaches the South Platte River. A new recreational wave feature, re-designed people spaces,  and the new Urban Loop Trail will complement the river restoration.

Birch is collaborating with our partners S2O Design and Engineering, Black Creek Hydrology, Calibre Engineering and landscape architects Wenk Associates on the final design, permitting, and implementation of the stream restoration for Reach 5.  Birch Ecology completed the wetland delineation and functional assessment and is currently preparing the Individual Wetland Permit Application and supporting studies including the Stream Quantification Tool, and the wetland mitigation and monitoring plan. Birch’s plant ecologists developed the native plant palette and specifications for the restoration, and we are partnering with landscape architects Wenk Associates to develop the ecological landscape design.  In addition, we are collaborating with Wenk, Revesco Properties, and stakeholder groups to develop a concept plan for an interpretive trail highlighting indigenous uses of native plants and their connection to the river’s ecology.

The stream restoration design process is ongoing, with construction planned to begin in winter 2021.

Design Team Partners: S2O Design and Engineering, Black Creek Hydrology, Calibre Engineering, Wenk Associates, Otak, Simons & Associates, Turner Construction Company, ECI Site Construction Management, Colorado School of Mines.

 

South Platte River Restoration Overview
Confluence Sediment 2400 x 1600
Sediment buildup behind the Confluence Park Dam has contributed to a shallow, widened channel that cannot contain the 100-year flood. The restoration project will re-design Confluence Park, restore habitat connectivity and remove the sediment that extends upstream to I-25.
Confluence Park Dam
The 7-ft high dam at Confluence Park is also a barrier to fish passage, and the sediment buildup reduces the habitat quality for fish. The dam and sediments will be removed as a part of the restoration project, and a new multi-stage channel will provide improved habitat conditions for fish.
Conceptual image of the restored stream channel adjacent to The River Mile development by Wenk Associates. The habitat creations and in-stream improvements will support increased ecological functioning.
South Platte River Sandbar Willows
Sandbar willow wetlands line the banks of the South Platte River near Elitch Gardens Amusement Park. The restoration plan will establish a more diverse riparian corridor with forests, shrublands, wetlands, and grassland habitats.
Bedload Sampling 2400 x 1600
Engineers from S2O Design assisting Black Creek Hydrology with bedload sampling. The data were used to develop sediment transport models to verify the design of the restored channel will effectively pass sediment. The U.S. Army Corps of Engineers assisted the team by releasing a pulse of water from Chatfield Reservoir to permit a measurement to be taken during higher flows.
The River Mile
Community involvement and stakeholder groups have played an important role in shaping the design of what has been called a "once in a generation" project for the City and County of Denver. The team held one of many stakeholder meetings at the Children's Museum in March 2020.
The River Mile
Image courtesy of Revesco Properties
Site context by Wenk Associates