Expansion study proposed for Bear Creek Lake reservoir

Bob Wooley
bwooley@coloradocommunitymedia.com
Posted 6/16/21

Water. It may be the defining issue of the American West. As the population of the Front Range continues to swell, the need to find solutions to the vexing problem of water usage persists. Bear Creek …

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Expansion study proposed for Bear Creek Lake reservoir

Posted

Water. It may be the defining issue of the American West. As the population of the Front Range continues to swell, the need to find solutions to the vexing problem of water usage persists.

Bear Creek Lake, sitting on the edges of Lakewood and Morrison, is currently allowed to store 2,000-acre feet of water. A plan proposed by the Army Corps of Engineers (which builds and regulates dams) would expand that capacity to 22,000-acre feet of water storage — a number so large, it has some area residents asking, “Why?”

Katie Gill, a Morrison resident, first read about the plan in the Bear Creek Watershed Association newsletter. 

She says at first she thought it was surely a typo — that they must have put an extra zero on the number.

So, Gill started doing what any retired teacher would do — her homework. And sure enough, the number was accurate. The state did want to research adding 20,000-acre feet of water storage to the lake.

“This really became a topic with the publishing of the Colorado Water Plan in 2015,” she said. “And that plan was written, estimating the population in Colorado would double by 2050.”

Gill admits she hasn’t read the whole report, which she said is around 500 pages long, but gleaned enough from what she did read to learn the expansion of Bear Creek Lake is part of a bigger goal of adding 500,000-acre feet of water storage for Colorado.

“The 20,000-acre feet increase in Bear Creek Lake would make up that 5%, and I think that’s a little bit too much to ask of our little park,” she said.

Gill readily admits the park probably needs to be part of the solution and says she’s not a “not in my backyard” type. 

She also realizes that water storage is important, allowing the state to capitalize on the high-water events that may be few and far between, instead of seeing that unallocated snowmelt run downstream, being lost to the state. 

In 2016, the state legislature authorized cost-sharing for the Bear Creek Reallocation Study, a three-year feasibility study that would look at environmental and economic impacts of the project. The state legislature and the Corps of Engineers shared the cost of the study. 

The Colorado Water Conservation Board, a division of the Department of Natural Resources, would oversee the study project.

Bear Creek Lake is not the Lone Ranger in this scenario. Many other Colorado reservoirs are being looked at for additional storage capacity authorization as well.

In fact, according to Gill, Bear Creek, Chatfield and Cherry Creek are all part of what’s known as the “Tri-Lakes Project.” She says the three dams were originally built under the Flood Control Act after some devastating floods in the 1960s. 

The “reallocation” moniker on the proposal, she says, refers to reallocation of use.

“The use of this infrastructure has always been flood control,” she says. “Now, they want to add a use to it and reallocate some of that capacity for water storage.”

Ultimately, the Cherry Creek proposal was not approved because of flood concerns. The Chatfield proposal was approved. But after being held up for years in a court case brought by the Audubon Society, the volume of water has not yet been increased. 

The Bear Creek study was set to begin in 2019 but was delayed to perform a semi-quantitative risk assessment, which found that increasing storage volume would create increased flood risk, but the risk would be within tolerable limits.

But Gill says the additional flood risk isn’t the only concern. She says the expansion would cover about 493 acres of the 1800-acre park. 

In fact, a 2017 memo from the Directors of Public Works and Community Resources to the Lakewood City Council, said the increase in the surface area of the reservoir would be 450%. 

By contrast, the proposed 20,000-acre feet increase of storage volume at Chatfield represents a 39% surface increase due to the vast difference in size between the two reservoirs.

“What is proposed in our park is so much more devastating than what was proposed for Chatfield,” Gill says. “Almost a mile of Bear Creek would be inundated, and almost a half-mile of Turkey Creek.”

She thinks the expansion could cause irreparable damage to the riparian ecosystem (land that interfaces with a river or stream).

Lakewood has, so far, not signed on to take part in the expansion program. The city has a lease to manage the park until 2040 but has no authority in this matter. 

To be even more clear, as of now, the people of Lakewood would not benefit directly from the extra water storage. Northern corridor communities like Berthoud, Brighton and Dacono would be the beneficiaries of the extra water storage in Bear Creek Lake. There would also likely be no additional recreational benefit to the expansion because of “unconstrained yield,” which deals with allocated and unallocated water rights. In other words, there is usually less water in the system than is already spoken for, so more holding capacity would not create an excess of water.

Another of Gill’s concerns is that it’s unlikely, based on historical data, that there would actually be enough water to keep the reservoir filled at the increase levels. She worries that could lead to a situation in which vast areas of dry lakebed dominate the park for three out of every four years.

Finally, she says the shallow depth of large portions of the Bear Creek Lake expansion area would make it a more inefficient solution because the lake would suffer higher levels of evaporative loss compared to a deeper reservoir holding the same amount of water.

Erik Skeie, Special Projects Coordinator for the Colorado Water Conservation Board, is taking the lead on the Bear Creek project. He says the plan for the expansion originally came from the Corps of Engineers when they realized the dams at Bear Creek, Chatfield and Cherry Creek had been overbuilt and were capable of potentially holding the additional level of storage. 

Skeie says when the Corps approached CWCB with a plan to do the feasibility study, they accepted because they were in the middle of writing the water plan and figured the state would need an additional 400,000-acre feet of storage by 2050.

He said right now, the state is only holding a tiny amount of water at Bear Creek compared to what they could potentially store, and the ability to use an existing resource to store additional water, made the study worth doing. 

“We kind of thought this was a no-brainer to investigate whether or not we could use this pre-existing bucket.”

According to Skeie, it’s unclear when the study will move forward, but he does anticipate it will happen at some point.

He wants to make it clear to all interested parties that as soon as he knows more about the timeline, he’ll make that information available.

“There will be a very in-depth public comment process through the entire thing,” he says. “The Corps has a policy that they want to conduct all feasibility studies within three years of the go date. So, it would be three years (to complete the study) and as far as public comment goes, I believe the first opportunity for public involvement would be no more than 60 days after the first internal scoping team meeting.”

He said the public comment process would include the corps, CWCB, City of Lakewood and folks from the Bear Creek Watershed Association.

Skeie stresses that the CWCB will try to mitigate as much impact from the project (should it move forward) as they possibly can. He says although the additional 20,000-acre feet of water is a sizable chunk compared to the amount currently being stored, the dam itself is capable of storing 57,600-acre feet of water. And in an emergency situation, it would be capable of storing up to 75,000-acre feet of water.

Skeie said concerns over ecological impact are very valid and would be taken into consideration in the feasibility study. He said additional mitigation steps were taken at Chatfield, and the same would hold true for Bear Creek Lake.

As for Gill’s “dry lakebed” concerns, Skeie said CWCB had done some unconstrained yield analysis that showed there would be an average of 20,000-acre feet of water available, but admitted that some years, as much as 80,000-acre feet would be available for diversion from Bear Creek, while in other low-water years, as little as 2000-acre feet would be available.

2,000 - Current acre foot water storage at Bear Creek Lake

22,000 - Acre foot volume being studied for the lake

325,851 - US gallons that equal an acre foot

500,000 - Additional acre foot storage needed to meet state population growth

493 - acres the additional water would take from the surrounding parkland

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