A legal complaint against the Army Corps of Engineers (the Corps) regarding the Gross Reservoir expansion project was filed in 2018 by a coalition of environmental organizations. It was dismissed in 2021 by a federal judge with the U.S. District Court in Denver.

The environmental coalition appealed the dismissal, and in 2022 the United States Court of Appeals for the Tenth Circuit ruled that the case was improperly dismissed and referred it back to the District Court. The coalition refiled their complaint this September and are proceeding with a court hearing expected in the middle of 2024.

The coalition is composed of both local and national environmental organizations. The lead plaintiff is Save The Colorado (savethecolorado.org) led by Executive Director Gary Wockner. The other organizations involved are The Environmental Group (tegcolorado.org), Wildearth Guardians (wildearthguardians.org), Living Rivers (livingrivercolorado.org), Water Keeper Alliance (waterkeeper.org), and the Sierra Club (sierraclub.org).

The lawsuit contends that the Corps failed to consider other alternatives to the Gross Reservoir expansion that are less damaging environmentally, which violates the Clean Water Act (CWA) and the National Environmental Policy Act (NEPA). The second contention is that the Corps failed to consider the impact of climate change on stream flows. A third contention is that Denver Water projections for demand were overstated, while Denver Water conservation measures over the years have been effective in lowering demand to the point that the project isn’t needed.

If the coalition is successful in their lawsuit, then it would invalidate the permits issued by the Corps and U.S. Fish and Wildlife Service (FWS) and stop construction of the project until new permits could be obtained.

The history of the project leading up to this moment is this: In the aftermath of the Hayman wildfire in 2002, Denver Water determined that they were too dependent on their Southern Water Collection system, which included Cheesman Reservoir. After the fire, the reservoir became clogged with ash and charred debris. If the reservoirs become compromised and the water unusable, Denver Water felt they would not be able to meet demand.

To become more balanced and less vulnerable to disruptions in their water supplies, Denver Water sought to obtain additional water for their northern water collection system. In 2003, Denver Water revised their Integrated Resource Plan (IRP) and projected their need out fifty years. The plan projected demand exceeding supply by 2016. Denver Water applied for a Section 404 CWA permit in 2003 to address both reliability issues with the Moffat Collection System and vulnerability issues with the entire system using demand projections from their IRP.

The Corps issued an initial Environmental Impact Statement (EIS) in 2008 and a final in 2014. In 2017, the Corps issued their Record of Decision (ROD) and Section 404 permit. In 2018, the environmental coalition led by Save The Colorado filed a suit claiming violations in the process of the review regarding CWA and NEPA regulations. In 2021, a federal judge dismissed their lawsuit. Denver Water started construction in 2022 with a completion date of 2027. In 2022, an appeals court ruled the dismissal improper and reinstated the lawsuit.

The environmental coalition is arguing that the Corps didn’t fully review the potential environmental damage caused by the expansion. A complete review would have included the potential effects to the environment of clear-cutting 500,000 trees, blasting and mining 1.6 million tons of rock, the release of “freezing flow” cold water into South Boulder Creek with adverse impact on aquatic ecosystems, and elevated reservoir mercury levels that could affect fish and human health.

Nor were climate change impacts included in the Corps’ analysis. Current research models indicate that a 1-degree rise in temperature results in a nine percent decrease in stream flow. Denver Water is anticipating acquiring about 18,000 acre feet of water per year (AF/yr) from the Colorado River basin, pumping the water through their Moffat Tunnel pipeline into Gross Reservoir. The reservoir expansion is projected to triple capacity from 42,000 acre feet to nearly 120,000.

The coalition lawsuit contends that the Corps failed to include climate change effects on the yearly yield to determine if 18,000 AF/yr will even be feasible in 20 years. Rising temperatures may lead to far less than the five billion additional gallons of water per year the project would take out of the Colorado River Basin, which would render the expansion an expensive waste.

The Executive Director of Save The Colorado, Gary Wockner, said “Denver Water doesn’t need this water and failed to consider the consequences of climate change.”

The lawsuit also addressed violations of the Endangered Species Act (ESA) in that the FWS did not issue a biological opinion in regard to the future of the green lineage cutthroat trout in Grand County and whether it should be considered an endangered species.

In terms of timelines, there will be several more months before the briefings are complete. The initial brief of the Department of Justice, representing the Corps, is due by November 6, 2023. Denver Water has 14 days after that to file their reply. The environmental coalition plans on filing their next reply in January 2024. They project that the suit will go to court for resolution sometime in the middle of 2024.

In the meantime, Denver Water can continue to expand Gross Reservoir.

For more information about Denver Water and the project, check out their website at denverwater.org/grossreservoir. To follow the ongoing work from an environmental stance, check out The Environmental Group at tegcolorado.org/