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Getting a (big) jump on a healthy environment

Denver Water completing required stream and habitat improvements years ahead of final go-ahead for Gross Reservoir expansion.

In its nearly 20-year (and counting) process to secure approval to expand Gross Reservoir, Denver Water has committed to numerous environmental improvement projects, both on the Front Range and the West Slope.

While most of the projects are contingent on approval of the reservoir expansion, Denver Water has moved forward and even completed several of them — even as the expansion project awaits a final green light through Boulder County’s local land-use process and works through challenges in the courts.

A scene from the Mammoth Gulch area that is part of the scenic Toll Property near the east portal of the Moffat Tunnel. Denver Water is conveying more than 500 acres of this area to the Forest Service to manage for public access. Photo credit: Denver Water.

It’s a sign of Denver Water’s dedication to the environment, to its partners and to the regulatory agencies that it is wrapping up environmental work years ahead of the first spade of dirt ever getting turned on the expansion of the reservoir in the foothills southwest of Boulder.

“Our No. 1 objective is to do right by our partners, by our customers and by the environment,” said Jeff Martin, project manager for the Gross Reservoir Expansion Project. “We’re committed to doing the expansion project the right way, so it made sense to move ahead early with these projects, to show — and not just talk about — our dedication to Colorado’s people and its ecosystems.”

Several projects designed to offset some of the impacts of the reservoir expansion such as work to improve fish habitat, to protect water quality and to set aside open space were essentially finished even before Denver Water received the Federal Energy Regulatory Commission’s Order last July approving the project.

Here's a brief look at some of the biggest Gross Reservoir expansion mitigation projects already wrapped up and their role in improving environmental conditions:

  • Completed Williams Fork River Restoration Project. Denver Water worked with Colorado Parks and Wildlife with the support of Grand County Learning By Doing partners in 2019 to restore river habitat on the Williams Fork River, upstream and downstream of the Williams Fork Reservoir, including the Kemp Breeze State Wildlife Area. 

    The project increased habitat diversity for all life stages of trout through work that reshaped the river channel, added large woody  debris, and created deeper pools and more variety of rock riffles and point bars. All of it was designed to create more opportunities for trout to eat, thrive and reproduce.
  • Constructed two Aquatic Organism Passage culverts near the west portal of the Vasquez Tunnel. These AOP culverts are located near Winter Park and were completed in 2019 and 2020. The AOP culverts allow aquatic organisms to avoid the roadway to migrate upstream more easily.

    Many aquatic species, including fish, amphibians and macroinvertebrates, can benefit if the stream habitat under the road is more like a natural stream with a rocky bottom, with flowing water that behaves as it would outside the human-made culverts the new AOP culverts replaced. The passages are especially helpful to boreal toads, a species of “special concern” that is being impacted by the chytrid fungus and habitat loss.
Crews with Denver Water and the U.S. Forest Service meet prior to removal of a traditional culvert that was later replaced with an "aquatic organism passage." Traditional culverts are harder for aquatic species to navigate, particularly during high flows. Photo credit: Denver Water.
  • Conveyance of 539 acres of the Toll Property, located in near the east portal of the Moffat Tunnel in Gilpin County, to the Forest Service as open space for protection as part of the National Forest System. This remote area is an ecological gem. The property provides expansive undeveloped forested habitat for wildlife and supports unique wetland types and mature riparian plant communities. Denver Water is in the process of conveying these scenic parcels to the Forest Service for management and public use.

    This property conveyance will provide additional protection for lands near two wilderness areas (Indian Peaks and James Peak) and the Arapaho National Forest, and complements a larger landscape protection effort led by The Conservation Fund.
  • Improved flume and telemetry equipment to upgrade streamflow measurements. New equipment at five locations will provide Denver Water, the Forest Service and Learning By Doing more detailed and real-time information on streamflows at creeks in the Fraser River watershed. 

    More accurate data will help water managers, including Denver Water, understand streamflow and how flows may be impacting temperatures and aquatic habitat.
  • Completed South Boulder Creek Restoration Project: Starting in 2018 and ending in the summer of 2019, Denver Water partnered with the city of Boulder to restore a 2-mile section of South Boulder Creek severely damaged in the record floods of 2013. The project targeted habitat improvements for fish.

The completion of two other major projects over the past several years are the result of the Colorado River Cooperative Agreement, which has ties to the expansion of Gross Reservoir. 

  • Since 2013, Denver Water has partnered with the Colorado Department of Transportation, Grand County and the town of Winter Park to capture traction sand that washes off Highway 40 and accumulates in the Fraser River. Annual trapping and removal of the sediment has translated to the removal of more than 3,000 tons of sand. These efforts have led to dramatic improvements in water quality and aquatic habitat downstream on the Fraser River.
  • Led by Grand County Learning By Doing partners, Denver Water participated in restoration of the channel and banks on the Fraser Flats section of the Fraser River west of Winter Park in 2017. Known as the Fraser River Habitat Project, this work included willow plantings that will shade the river and help to reduce water temperatures. It has resulted in an initial significant increase in the fish population — and attracted anglers to a 0.4-mile section newly opened to public fishing.
A wide view of some of the work on Fraser Flats shows how willows can shade the banks and cobble lining can direct flows into the central channel and create depth and pools – all habitat attractive to fish. Photo credit: Denver Water.

Denver Water continues to push forward on several additional projects to protect fish and improve stream habitat. Some of the work was slowed by the COVID-19 pandemic in 2020.

These completed projects, along with work in progress and projects still to come, are part of a variety of agreements related to Gross expansion. Those include the Federal Energy Regulatory Commission Order, an agreement with the U.S. Forest Service and the CRCA.

Completion of the Gross Reservoir Expansion Project will allow for additional enhancements for the environment: a larger reservoir on the East Slope will give Denver Water more flexibility in how it moves water around its collection system on the West Slope. 

That means for average and wet years, more water can be made available for coordinated releases in the Fraser and Williams Fork river watersheds in collaboration with Grand County Learning By Doing partners. Flushing flows and periods of high stream temperature will be targeted for these coordinated releases. 

From Denver Water’s perspective, completing projects years ahead of full regulatory approval of the reservoir is simply the right way to do business and continues the collaborative process.

“The Gross Reservoir Expansion Project will not be judged by whether it is completed,” Martin said, “but rather how it is completed.”

Brown trout like this one descended on newly restored river habitat on the Williams Fork River. The habitat work led to an intense flurry of spawning activity that surprised biologists. Photo credit: GEI Consultants.