Gross Dam to be tallest in Colorado
Project will cost $380M, tripling water storage after years-long debate.
The Army Corps of Engineers has greenlighted a $380 million Denver Water project to raise the height of the Gross Dam, tripling its water storage and nearing the end of a path 14 years in the making.
Denver Water CEO Jim Lochhead said the project, which was approved late Friday, was important to add balance and resiliency to the agency’s system. The dam expansion still needs approval from the Federal Energy Regulatory Commission to increase its hydropower capacity.
“It’s been a long haul,” Denver Water Board president Paula Herzmark said of Friday’s decision. “We are just ecstatic, just elated that this permit is now in place and we can begin. To have the insurance that we’re going to have this additional source of supply as our community grows.”
By raising the dam wall to 471 feet from 340 feet, Denver Water will be able to store nearly 119,000 acre-feet of water, up from 42,000 acre-feet. The extra water sent into the system will be able to serve 54,000 single-family residential homes a year. The additional height will also make Gross Dam, which is 5 miles southwest of Boulder, the tallest dam in Colorado.
Colorado Trout Unlimited was happy with the news. The group has been working with Denver Water to make the project environmentally friendly, Trout Unlimited counsel Mely Whiting said.
The project includes an environmental pool to divert water to streams that need it. It also led to the Learning By Doing Cooperative Effort that brings together groups to monitor stream conditions and quickly take action when needed. Denver Water is also giving about $25 million to Grand County and other counties for environmental advancements.
But as is common with
dams, not everyone is happy with holding more water behind walls.
“We believe the Army Corps has violated the law,” said Gary Wockner, an environmental activist with Save the Colorado who is leading a coalition fighting the project. “Denver Water doesn’t need the water, the Colorado River is already severely drained and depleted, and the people of Boulder County don’t want the project. The courts need to take a hard look at this decision.”
In a statement released Saturday morning, Wockner pointed to a 20 percent drop in water use since 2002 despite a 10 percent customer increase as evidence that the agency doesn’t need more stored water. He added that construction for the dam will have a negative environmental impact on the surrounding area.
Lochhead countered that the extra water will be needed as current conservation efforts won’t be enough to cover the growing population and effects of climate change. He added that Denver Water has been working with environmental groups and local and federal governments since the start to not just mitigate damage, but rather improve rivers.
Lochhead acknowledged that the five years of construction will be hefty, especially the three years of intensive concrete placing. He said Denver Water worked with the local residents to mitigate impacts and said an on-site quarry will be built to reduce truck trips.
“With a warming climate and with growth and other issues in our system, we need to make sure that our system is resilient in the long term,” he said.
The Associated Press contributed to this report.