Gross Reservoir Expansion Project

Protecting Colorado Rivers and Streams

Providing a Net Environmental Benefit for Colorado

Denver Water has committed to more than 60 different mitigation and enhancement projects on both the West and East Slopes with a total cost of more than $20 million. Denver Water will be collaborating with numerous stakeholders to preserve the aquatic environment on a cooperative basis. Some of the projects include:

Greenback Cutthroat Trout Recovery

Denver Water is partnering with the U.S. Fish and Wildlife Service, U. S. Forest Service and Colorado Parks and Wildlife to restore and expand cutthroat trout habitat at several locations in Grand County.

South Boulder Creek Habitat Restoration

Denver Water will restore approximately two miles of South Boulder Creek with the City of Boulder

Williams Fork Restoration

Denver Water will restore approximately two miles of the Williams Fork River in Grand County.

Fraser Sediment Ponds

Denver Water has partnered with Colorado Department of Transportation, Grand County, and the town of Winter Park to capture traction sand used on Hwy. 40 to improve water quality and trout habitat in the Fraser River.

Environmental Pool

Denver Water will establish a 5,000 acre-foot environmental pool in Gross Reservoir that will be used to increase streamflow during low flow periods. This will benefit 17 miles of aquatic habitat in South Boulder Creek from Gross Dam to its confluence with Boulder Creek.

Learning by Doing

Denver Water is a partner in Grand County’s groundbreaking “Learning By Doing” program –
pursuing the goal to “maintain, and, where reasonably possible, restore and enhance the conditions of the aquatic environment in Grand County.”

Long Term Water Quality Monitoring

Denver Water will monitor stream temperatures,
water quality, aquatic insects and channel stability in numerous streams on both West and East slopes.

Stream Restoration on the North Fork South Platte River

Denver Water will prepare a Stream Habitat Improvement Plan to benefit aquatic habitat on the South Platte River.

Denver Water is committed to preserving and enhancing the environment and habitats that make up our watersheds. We’re proud that in issuing the Gross Reservoir Expansion Project’s 401 Water Quality Permit, the Colorado Department of Public Health and Environment noted the project will have a “net environmental benefit” on the state’s water quality.

Colorado Rivers and Streams

This project takes unprecedented steps to enhance watersheds and protect the communities within them. Nearby rivers will benefit, as we go beyond offsetting the impacts of the reservoir expansion project to give South Boulder Creek and the Fraser, Williams Fork, Blue and Colorado Rivers better protection than they are receiving today.

Through the Colorado River Cooperative Agreement, the Gross Reservoir Expansion Project will provide the following benefits:

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In partnership with the Cities of Boulder and Lafayette, establishes a 5,000 acre-foot environmental pool, which will enhance stream flow in South Boulder Creek during low flow periods, benefiting 17 miles of aquatic habitat.

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Commits Denver Water to working collaboratively with Grand County to use Denver Water’s system flexibility to benefit the aquatic environment.

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Ensures more water in the Fraser and Blue Rivers in dry years.

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Funds multiple water improvement and stream restoration efforts in collaboration with county officials, Trout Unlimited and other interested parties.

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Improves aquatic habitat:

$50,000 committed to stream channelization improvements on the Fraser River.
Collaborative effort between Denver Water, Colorado Department of Transportation, Grand County and the U.S. Forest Service to modify Denver Water’s diversion structure on the Fraser River to allow the removal of road sand, which has improved stream quality on the Fraser River.

Protecting Our Resources

Our highest responsibility remains to serve 1.4 million people today and a growing population in the future. We strive to do so while minimizing our environmental footprint and working collaboratively with our neighbors to protect and enhance supplies for agriculture, riparian habitat, stream health and many other needs.To protect our watersheds and endangered species, Denver Water is:

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Providing $16.5 million for the From Forests to Faucets partnership, to be matched by the U.S. Forest Service (total of $33 million), for forest health initiatives in our watersheds.

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A leader in the Colorado River Endangered Fish Recovery Program, a strong coalition of states, agencies and environmental groups cooperating in the restoration of habitat for the humpback chub, Colorado pike minnow and other fish species.

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A leader in the Platte River Recovery Implementation Program, combining multiple resources to restore and protect habitat for the whooping crane and other endangered species.

Latest News / Blog

Denver Water hires contractor for Gross Reservoir Expansion Project

HydroWorld.com – July 11, 2019 – “This is a major milestone in our 16-year effort to expand Gross Reservoir, as its original designers intended decades ago, to ensure a more reliable water supply in a future marked by greater uncertainty in weather patterns,” said...

Controversy over Denver Water’s Gross Reservoir expansion offers a glimpse into water woes in the West

Colorado Sun – July 10, 2019 – "Denver Water has a long history of securing water before there’s a crisis,” said Patty Limerick, director of the CU Boulder’s Center for the American West and former Colorado Historian. “The Gross Reservoir expansion is a perfect...