A federal judge has thrown out a legal action from multiple environmental organizations seeking to halt the expansion of a key Denver Water storage facility, citing no legal authority to address the challenge.

“This decision is an important step,” said Todd Hartman, a spokesperson for Denver Water. “We will continue working earnestly through Boulder’s land-use process and look forward to beginning work on a project critical to water security for 1½ million people and to our many partners on the West Slope and Front Range.”

The expansion of Gross Reservoir in Boulder County is intended to provide additional water storage and safeguard against future shortfalls during droughts. The utility currently serves customers in Denver, Jefferson, Arapahoe, Douglas and Adams counties. In July 2020, the Federal Energy Regulatory Commission gave its approval for the design and construction of the reservoir’s expansion. The project would add 77,000 acre-feet of water storage and 131 feet to the dam’s height for the utility’s “North System” of water delivery.

FERC’s approval was necessary because Denver Water has a hydropower license through the agency, and it provided the utility with a two-year window to start construction.

A coalition of environmental groups filed a petition in U.S. District Court for Colorado against the U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service, seeking to rescind those agencies’ previous authorizations for the project. They argued the agencies inadequately considered the environmental impact of expansion.

According to their petition, hazardous activities related to the project would allegedly include “around-the-clock construction activities for at least four years; creating constant safety and health hazards from heavy truck traffic, associated dust, and air and noise pollution; and compromising the quality of life of thousands of landowners, residents, and visitors drawn to the South Boulder Creek area for the quiet, solitude, and scenic beauty that now exist.”

The groups suing to stop the reservoir expansion included Save the Colorado, The Environmental Group, WildEarth Guardians, Living Rivers, Waterkeeper Alliance and the Sierra Club. They also argued Denver Water’s projections for water demand were “vastly overstated,” and that the entire project failed to account for climate change.

However, the Denver Water pointed out that under federal law, appellate courts, not district-level trial courts, are responsible for hearing challenges to FERC approvals. By challenging the environmental review process that led to the project’s go-ahead, the government argued, the environmental organizations raised issues “inescapably intertwined with FERC’s licensing process.”

On Wednesday, U.S. District Court Judge Christine M. Arguello agreed that the groups’ challenge was indeed wrapped up in the FERC approval.

“[W]here a party does not challenge a FERC order itself, but challenges another agency order that is inextricably linked to the FERC order, the FPA’s exclusive-jurisdiction provision applies and precludes this Court from exercising jurisdiction,” she wrote in dismissing the case.

The Daily Camera reports that Boulder County’s approval is the final step for the expansion project.

“We are disappointed by the court’s decision. The dam and diversion project at issue in this case will steal even more water from the Colorado River and result in the tallest dam in the state of Colorado,” said Jen Pelz, program director at WildEarth Guardians. “We believe that the critical issues raised in our litigation must be resolved on the merits to ensure that people and the environment are not harmed.”

William S. Eubanks II, an attorney representing the environmental organizations, said he was considering all options going forward.

The case is Save the Colorado et al. v. Semonite et al.