Denver Water’s permit from the U.S. Army Corps of Engineers for the ongoing expansion of Gross Reservoir violates the Clean Water Act and the National Environmental Policy Act, according to a ruling Wednesday from a U.S. District Court judge.
Senior federal judge Christine Arguello did not order Denver Water to stop construction in Boulder County, which has been underway since 2022, but said the environmental plaintiffs have a right to relief from any damage that will occur to surrounding land and forest once the dam closes and the expanded pool rises.
“To the extent Denver Water disagrees, it has only itself to blame — because Denver Water chose to proceed with construction despite the obvious risk posed by pending federal litigation,” according to the ruling, in the U.S. District Court for Colorado.
The court faulted the Army Corps for permitting construction without fair consideration of all the alternatives that might avoid dredging and filling “waters of the United States” like South Boulder Creek, where Gross sits. The judge said the Corps should also have more thoroughly analyzed if climate change and lower precipitation in the Western Slope catchment area mean that Denver Water won’t have the right in some years to put extra water into Gross Reservoir.
A lawful permit analysis under the federal environmental acts “requires confirming that there will even be additional water to impound,” the judge wrote.
The ruling dismissed one of the plaintiffs’ claims, that the U.S. Fish and Wildlife Service failed Endangered Species Act requirements to screen the permit for potential damage to protected wildlife.
Arguello ordered Denver Water to start talks with the plaintiffs, including Save the Colorado, the Sierra Club, WildEarth Guardians and others, on how to “remedy” the Corp’s violations of the two key environmental laws.
Denver Water said Thursday afternoon, “While we are reviewing the judge’s ruling pertaining to the Record of Decision issued by the U.S. Army Corps of Engineers in 2017, Denver Water remains focused on maintaining the safety and forward progress of the project.”
Because the dam includes a hydropower station that is also being built as part of the expansion, portions of the project are regulated by the Federal Energy Regulatory Commission. Denver Water noted in its statement that FERC requires completion of the dam by 2027.
“It’s critical we continue with construction on schedule to ensure the integrity and safety of both the current project configuration and future dam and to meet the federally required completion deadline from FERC,” Denver Water said.
The Army Corps of Engineers regional office in Omaha said late Thursday that any comments on the permit lawsuit or rulings would have to come from the U.S. Department of Justice.
The environmental coalition was quick to claim a big victory from the ruling.
“It’s huge. Put that in capital letters,” said Save the Colorado founder Gary Wockner in an interview. “It’s a stunning victory for the Colorado River, for the people of Boulder County and Grand County,” Wockner said. “Boulder County, because of where this massive project was being built, and in Grand County, because their rivers were going to be further drained. And it’s a victory for the rule of law.”
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“The court’s ruling in our favor is a monumental win that will help safeguard the waterways and communities of Boulder County and beyond from this irresponsible and destructive project,” said Daniel E. Estrin, general counsel and legal director for coalition partner Waterkeeper Alliance. “The Army Corps’ consideration of reasonable alternatives to Denver Water’s preferred project and its determination of the least environmentally damaging practicable alternative were fatally flawed.”
The plaintiffs were still reading the 86-page ruling and have not had time to confer on whether to seek an injunction against further construction at Gross Reservoir, or what environmental mitigations they might seek in conference with Denver Water, Wockner said.
Work crews in western Boulder County are pouring vast amounts of concrete daily to thicken the lower walls of the existing Gross dam, on their way to raising the 340-foot dam by 131 feet. The higher dam will more than double holding capacity for Gross Reservoir, while flooding surrounding forest land.
Denver Water worked for decades permitting the construction, arguing new storage was needed in Boulder County to serve northern communities, balancing the rest of Denver’s system that is heavily concentrated on supply and delivery south of the metro area. Denver Water serves a total of 1.5 million customers, many in the city of Denver, but many more through delivering water to suburbs from Wheat Ridge and Lakewood to Littleton and Centennial.
Denver Water’s Thursday statement said the Gross expansion “has been analyzed and permitted in various forms by no fewer than seven state and federal environmental agencies, and has consulted extensively with environmental organizations, nonprofits, the public, and other stakeholders to identify efforts to enhance and reasonably restore resources on both the West Slope and Front Range.
“Denver Water looks forward to working through the legal process to address any potential remedies and move this critical project toward completion,” the statement said.
Save the Colorado and various coalition partners have had success slowing or stopping dam and river alteration projects, as part of their mission to halt further diversions of western-flowing Colorado River water to Front Range water agencies and to leave more in the rivers for wildlife. Wockner noted Thursday that they have also sued over permits for the sprawling $2 billion Northern Water effort called Northern Integrated Supply Project.
“Court precedents matter,” Wockner said, pointing to the potentially wide impact of the Gross Reservoir ruling. Environmental lawsuits objecting to Army Corps dam permits often pivot on claims the Corps and the water agencies in question did not seriously analyze less costly and damaging water supply alternatives, including increased conservation.
The judge said the parties should file briefs on their positions if they don’t reach an agreement by Nov. 15. The judge noted that concrete pouring will be ending for the winter in November, creating a pause in activity during which remedies can be discussed.
“It is ordered that counsel for all parties shall confer and attempt in good faith to reach an agreement as to remedies concerning the issues on which the Corps was not in compliance,” Arguello wrote.