Colorado: Corps of Engineers pushes back decision for Denver Water’s Moffat Collection System expansion project

Concerns about Fraser River environmental impacts remain

Denver Water seeks to increase diversions from the Fraser River in Grand County.

By Bob Berwyn

FRISCO — Denver Water’s plan to divert more Upper Colorado River flows to the Front Range is on hold for at least another year, as the U.S. Army Corps of Engineers this week announced that it won’t finalize the environmental study for the Moffat Collection System expansion project until January 2014.

“We had projected a date of January 2013 … It was not intended to be a firm date, but it got presented as a firm date,” said Tim Carey, chief of the U.S. Army Corps of Engineers regulatory office.

“I would not say this is a delay … We’re really trying to make certain that we have adequately studied and addressed the impacts,” Carey said, adding that the new release date is also tentative at this point.

Once the final environmental impact statement is released, there will be another opportunity for public comment before the Corps decides whether, and under what conditions, to permit a Section 404 Permit for the enlargement of Gross Reservoir, in Boulder County.

As the lead regulatory agency for the Moffat expansion proposal, the Corps is responsible for reviewing Denver Water’s proposal to ensure compliance with environmental and other federal laws. Documents related to the project are online at this Corps website.

Carey said the Corps has been working closely with the EPA and the Colorado Department of Public Health and Environment the last seven months to address some of the concerns raised by comments on the draft study.

As part of that process, the CDPHE became a partner agency on the project, which gives state health officials more access to developing information. Since the state agency also has to issue a water quality certification at the end of the process, its new status could help speed up the final stages of the review process, Carey explained.

“In the past, the state has done that after the Corps is done with their process. We decided we could be doing this more concurrently,” Carey said.

The project is being touted by Denver Water as a partial answer to drought woes and a way redress the imbalance between the southern and northern portions of the utility’s system. In the larger picture, the Moffat collection system expansion would also partly meet projected future water shortages, according to a Denver Water fact sheet.

The project envisions taking more water from the Fraser River system in Grand County during wet years and storing it in the expanded Gross Reservoir.

According to Denver Water, a draft mitigation plan for the Upper Colorado — developed outside the formal environmental planning process — includes measures that would improve conditions in the Upper Colorado — a conclusion that is questioned by conservation stakeholders, primarily represented by Colorado Trout Unlimited.

“We are pleased to see the state and federal agencies come together to commit to a sound timeline for the release of the Final Environmental Impact Statement for Denver Water’s Moffat Collection System Project next February,” Denver Water CEO and general manager Jim Lochhead said in a statement.

“We’re in the second year of a severe drought. If the Moffat Project were in place today, we would have been able to store more water during the high flow runoff two years ago that we could now use,” he said

According to Lochhead, existing agreements obligate Denver Water to maintain certain flows during dry years. In a dry year like this one, we would not be diverting additional water under this project,” he said.

Instead, Denver Water would actually be returning water to the environment, he said, describing the Moffat project as a win-win, benefiting the environment in dry year and creating additional water storage that the metro area desperately needs during the inevitable drought cycles.


The Fraser River already contributes a disproportionately large share of its water to transmountain diversions. Without adequate mitigation, increased diversions are likely to lead to unsustainable degradation of aquatic ecosystems, according to Colorado Trout Unlimited Director David Nickum.

“We assume this means they recognize they need to get more analysis into the assessment,” Nickum said. “The draft was badly flawed. It failed to address a lot of the impacts,” he added.

Nickum also said it’s important to remember that the so-called cooperative Colorado River agreement specifically did not address the environmental impacts of taking additional peak flows from the Fraser. The agreement, hailed as marking a truce in the West Slope-Front Range water wars, addresses current conditions in the Colorado River Basin, but not the impacts from future projects, according to Nickum.

Weaknesses in the draft environmental study include conclusions that the loss of peak flushing flows wouldn’t have a negative effect on the Fraser. Nickum said there’s solid science to show that the current diversions have already led to a sediment buildup that is harmful to aquatic life.

Any plan for future increased diversions must acknowledge those impacts and include meaningful mitigation measures,” Nickum said.

“You’re dealing with uncertainties and potential threshold effects when you get to these levels of diversions … up to 75 percent of the flows,”  he added, explaining that the final study needs to define those uncertainties and outline steps for adapting to unforeseen impacts.

That would include impacts related to stream temperatures — especially in the context of a changing climate. Increasing water temperatures are another critically limiting factor for aquatic ecosystems. Without adequate mitigation, the Fraser could be “diverted to death,” Nickum said.

“It’s more important to do this permit right than to do it fast. We urge the Corps to take these additional months to correct those deficiencies and ensure that the Fraser receives adequate protection … Denver residents and Denver Water customers want healthy rivers-and they’re looking to Denver Water and federal agencies to protect this magnificent resource. “


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