The Colorado-based federal appeals court agreed on Friday to allow construction to continue on a Denver Water project in Boulder County — only until it can come up with a longer-term answer for whether to keep in place a trial judge’s order freezing all further work.

On April 3, U.S. District Court Senior Judge Christine M. Arguello found that, as a result of federal law violations, the expansion of Gross Reservoir and Dam should cease permanently and any further construction on the ongoing project would stop temporarily. The pause on construction, Arguello wrote, would give her time to hear from engineers and determine what, if any, work would need to occur to stabilize the structure.

Denver Water quickly asked Arguello to put her order on hold while it seeks review in the U.S. Court of Appeals for the 10th Circuit. On April 6, she agreed to give the utility some breathing room by relaxing the pause on all construction while Denver Water appeals.

Denver Water then petitioned the 10th Circuit to allow construction to continue beyond the 14-day window Arguello afforded, noting her order came as the long-running project had reached 60% completion.

“This Order was entered days before Dam construction was set to resume for the 2025 season. If construction cannot proceed, Denver Water and its contractors must lay off hundreds of workers, the safety and stability of the Dam will be put at risk, the water supply shortage the Project is intended to address will be exacerbated,” wrote the utility’s lawyers, “and Denver Water will be precluded from complying with the Federal Energy Regulatory Commission’s order requiring it to construct on a set schedule and complete the Project in 2027.”

They added that the specific complications from halting construction include the lack of necessary components to control flooding, structural deterioration and the cost of rehiring workers if the project proceeds again.

Arguello’s “hostility to the Project was palpable,” Denver Water argued.

In an April 11 order, the 10th Circuit directed the environmental groups challenging Gross Reservoir’s expansion to respond to Denver Water’s request to permit necessary construction to continue while Arguello’s order is appealed. The circuit also gave Denver Water four days after that to respond — one day beyond the window Arguello initially allowed for further construction.

As a result, the 10th Circuit clarified that it was imposing its own stay on the portion of Arguello’s order prohibiting construction until it decides whether longer-term relief from her decision is warranted.

Meanwhile, Arguello has scheduled a hearing for May 6, where she will hear from experts about “what is reasonable and necessary to ensure that the dam, as it is currently constructed, will be structurally safe.”

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