Raising the 55-year-old dam near Boulder is essential to keep a stable water supply in a changing climate, utility says. Residents insist conservation could be just as effective.

Tucked out of view in the foothills southwest of Boulder, Gross Reservoir is a mountain oasis surrounded by pine trees, alpine flora and chattering wildlife.

On a typical summer day, hikers, campers and kayakers leisurely come and go, lured by the landscape’s beauty. Residents who live on the north shore of the reservoir take their dogs for a morning stroll on the path that twists around the pristine man-made body of water.

But by late 2020, a cacophony of heavy construction could bring the peace and quiet to an abrupt halt.

Denver Water — Colorado’s largest and oldest utility company — in July 2017 received one of the final permits needed to raise Gross Reservoir Dam by 131 feet to increase water storage capacity by 77,000 acre-feet, or an additional 25 billion gallons of Western Slope water.

The reservoir, built in 1954, is part of Denver Water’s extensive collection system, which provides drinking water to 1.4 million people (about a quarter of Colorado’s population).

The expansion, in the works for more than a decade, is part of the company’s long-term plan to help meet increasing water demands along the Front Range and buffer customers from future water-supply variability due to climate change.

Gross Reservoir Dam outside Boulder, on Monday, July 1, 2019. Denver Water is planning a major expansion of the reservoir that will increase height of the Gross Reservoir Dam by 131 feet and water storage by 77,000 acre-feet. (Chris Schneider, Special to The Colorado Sun)

The expansion will involve heavy construction for approximately five years, the removal of an estimated 200,000 trees and the creation of a quarry, near where the current boat launch is, to provide construction materials for the project. The south side of the reservoir will be closed to recreation during construction.

Denver Water has been met with sustained opposition from Boulder County residents and a handful of environmental groups who say the utility can address its water needs through expanded water conservation efforts on the Front Range. 

But with Colorado’s population growth showing no signs of slowing, water conservation may be inadequate to address projected shortages in the coming decades. 

Other concerns raised by opponents include sustained disruption to surrounding residents, increased traffic, health concerns and environmental impacts to fish and wildlife.

Gross Reservoir is filled primarily from snowmelt that flows from the Fraser River, a tributary of the Colorado River. The water is transported underground from west of the Continental Divide to the east by a pipeline called the Moffat Water Tunnel.

The controversy over the Gross Reservoir expansion, estimated to cost $464 million, echoes an all-too-familiar story: a highly contentious discussion of tradeoffs that has rippled across the Western United States for decades.

As cities and states across the West grapple with swelling population alongside diminishing water supplies as a result of climate change, water-resource agencies such as Denver Water are faced with the delicate task of balancing the health of ecosystems with municipal, agricultural and recreational needs. 

“The issue is actually quite simple,” said Doug Kenney, director of the Water Policy Program at the University of Colorado. “There isn’t enough water in supply to keep up with the demands. And it’s not going to get any better anytime soon. The population keeps increasing, and supply is becoming more and more variant due to climate change. We’ve entered a new era of water woes in the West.” 

Beverly Kurtz, who lives near Gross Reservoir Dam, is fighting plans to raise the dam to increase capacity. The $464 million project has had opposition since it was announced. Residents and environmental groups have sued to stop the expansion, saying they are concerned about environmental impacts and the lack of conservation efforts. (Chris Schneider, Special to The Colorado Sun)

Water woes: The reality of life in the West

Beverly Kurtz has a long history of opposing dams. 

An avid whitewater rafter, she has worked to thwart various water infrastructure projects throughout the Southwest. When she retired from her day job as a project manager at IBM, she turned her attention to fighting the Gross Reservoir expansion.

“Morning, noon and night, this is what I do,” said Kurtz, who moved to the north shore of Gross Reservoir nearly 27 years ago. “I had no idea when I moved up here that one day I would be fighting the dam in my very own backyard.”

Kurtz spoke in opposition to the expansion at the Boulder County Commissioners meeting on March 14, alongside dozens of other residents who live on the outskirts of the reservoir. At the meeting, Boulder County commissioners unanimously voted to require Denver Water to go through a local land-use permitting process called a 1041. (Denver Water has sued Boulder County to overturn this ruling. The lawsuit is pending.)

A coalition of environmental groups — including residents living around the reservoir — in December sued to stop the expansion, targeting a number of federal agencies and Denver Water for what the plaintiffs claim would be a violation of the Endangered Species Act and the Clean Water Act.

“The big picture is that the Colorado River is already one of the most endangered rivers in the United States and to take yet more water out of it is an environmental travesty,” Kurtz said. “We have to find ways to deal with our water needs in other ways, not by building bigger reservoirs.”

Jeff Martin, Denver Water’s project manager for the expansion project, doesn’t skirt around the controversy. He recognizes that the project is going to cause disruption and says that Denver Water has worked with the residents to find ways to minimize the project’s impact. 

“This has been a process,” Martin said. “We started in 2004, it took 13 years to move through the environmental assessment and permitting process. And we’ve made a lot of changes and adjustments to our plans since the beginning.”

Ellen Malan, of Denver, puts her boat in the water at Gross Reservoir outside Boulder. (Chris Schneider, Special to The Colorado Sun)

“No single solution is out there,” he said. “Our problem is rooted in demand and resiliency, and what I mean by resilience is that we have to make sure we have the water when we need it, and where. Our customers have done an incredible job saving water since the 2002 drought. We use the same amount of water today as we did in the late ’70s, with 450,000 more people in our service area.”

But water conservation doesn’t solve the utility’s storage imbalance problem, Martin added.

Within Denver Water’s collection system, 90% of the water is stored in its southern system, with only 10% being held in the northern system, which includes Gross Reservoir. During the historic 2002 drought, Gross was at 10% capacity. Martin said the expansion will help alleviate that imbalance.

According to the Colorado Water Plan, 80% of the state’s population receives its municipal water supply from forested, high-country watersheds — the same water that feeds many of the nation’s main waterways, including the Colorado, Arkansas and Rio Grande rivers. 

More than 60% of the water flowing through Colorado exits the state to downstream users in seven other states, as well as Mexico. Of Colorado’s remaining water — less than 5.3 million acre-feet — agriculture absorbs 89%, municipalities drink up 7% and large industries consume 4%.

MORE: Amid drought, a changing climate and population growth, can Colorado’s unique water law system survive?

Currently, Colorado uses three main strategies to address water shortages: infrastructure projects, the purchase of water rights, and water conservation. In order to address future water shortages, all three strategies must be utilized and optimized, Kenney said.

The current proposal for the expansion of Gross Reservoir offers a dramatically smaller environmental impact than building a new dam from scratch, which was Denver Water’s original plan.

The controversial 615-foot dam called Two Forks was planned to be built on the South Platte River about 25 miles from Denver. The plan was vetoed in 1990 by the EPA, which found it in violation of the Clean Water Act.

The dam would have flooded six towns and much of Cheesman Canyon, a wild area in the Pike National Forest beloved by trout fisherman, hikers, campers and boaters. The dam would have been larger than Hoover Dam in Nevada, transforming the canyon into a 7,300-acre reservoir and creating the largest man-made lake in Colorado.

After the Two Forks dam was denied, the expansion of Gross Reservoir became Denver Water’s alternative.

For Patty Limerick, director of the CU Boulder’s Center for the American West and former Colorado Historian, you can’t talk about water issues on the Front Range without first looking back in time. 

When early white explorers arrived here, they deemed the Front Range unfit for settlement due to lack of water. Today, 1.4 million Denver residents have access to clean drinking water due in large part to Denver Water’s enormous infrastructure web that diverts water from the South Platte, Blue, Williams Fork and Fraser river watersheds to be stored in a network of reservoirs spread over eight counties, including Dillon, Strontia Springs and Cheesman.

“One thing that I find fascinating, and is important to talk about, is the incredible amount of engineering that had to occur to make any of this possible in the first place,” Limerick said.

“We, as a society, have to recognize the improbable comfort that was made possible by a taken-for-granted, but truly astonishing, water infrastructure that was put in place a hundred years ago.”

As Colorado continued to develop in the mid-1900s, and in anticipation of water shortages in the future, Denver Water steadily secured large numbers of Western Slope water rights, which has allowed it to continue diverting water east across the Continental Divide.

“Denver Water has a long history of securing water before there’s a crisis,” Limerick said. “The Gross Reservoir expansion is a perfect example of that.”

Susan Stanley, of Boulder, and her dog Wile E. Stanley, paddle board on Gross Reservoir . Stanley said she comes to the reservoir often and opposes the dam expansion. (Chris Schneider, Special to The Colorado Sun)

She said the Boulder residents opposing the project come at the issue from a different perspective.

“They don’t want the expansion because of the environmental impact surrounding the reservoir,” Limerick said. “It’s more about the disruption it will cause to the people living around it.” 

“Unless all Colorado residents band together and tell the rest of the country how bad Colorado is, people will keep flooding into the state, simultaneously increasing water demands,” Limerick said.

The Colorado State Demography Office expects the state’s population to grow to 8.1 million by 2050, with about 85 percent of those people living on the Front Range. Colorado’s Water Conservation Board estimates the state will need between 538,000 and 812,000 acre-feet of additional water by 2050 to meet municipal and industrial demands.

“And then add climate change into the conversation, and things get messy real quick,” Limerick said. 

MORE: Even after a rush of snow and rain, the thirsty Colorado River Basin is “not out of the woods yet”

(Climate) Change on the horizon

Despite heavy snow and slow melt that spiked snowpack to an astonishing 517 percent of normal at the beginning of June and led climate watchers to declare the state free of drought for the first time in 19 years, Colorado’s future remains dry.

According to the U.S. Global Change Research Program’s Fourth National Climate Assessment, released in November, snowpack and streamflow amounts are projected to decline in parts of the Southwest, decreasing surface water-supply reliability for cities, agriculture and ecosystems.

The snowpack affects everything from drinking water for residents and irrigation for farmers to helping to mitigate wildfire throughout the state, said Joe Taddeucci, water resource manager for Boulder Public Works. Boulder doesn’t draw water from Gross Reservoir; its water supply is mostly from Northern Water, another giant utility.

“Each year, water-supply reservoirs fill primarily from snowmelt runoff. If we have a year of well-below-average snowfall, water suppliers may have to either draw on supply reserves or, in more extreme cases, ask water users to cut back on water use,” he said.

Sometimes, formal water restrictions have to be imposed, as California did in 2015. 

According to statewide meteorological records, Colorado’s climate has warmed by 2 degrees over the past three decades, and predictions show that the state could see an increase of between 2.5 and 6.5 degrees by 2050. 

With the persistent increase in temperatures throughout Colorado and much of the West, state officials are anticipating warmer winters, earlier springs and hotter summers — a shift that would drastically reduce Colorado’s spring-snowpack levels and increase the risk of drought and wildfire.

“The year 2018 was very similar to what we would expect to see under a climate change regime. And that was a very intense but short-term drought,” said Taryn Finnessey, senior climate change specialist with the Colorado Water Conservation Board. 

“We saw some reservoirs in the state declined by 50 percent in a three- to four-month period. So that obviously could not be sustained multiple years in a row,” she said. “Water providers are increasingly integrating climate change models into their water supply projections. They know that what we’ve seen in the past might not fully represent what we might see in the future. Denver Water is one of the more advanced utilities when it comes to this.” 

Finnessey says it’s not just about how much precipitation falls from year to year. It also has a lot to do with increasing temperatures, contributing to the long-term drying out of the West, a phenomenon scientists are referring to as aridification. As temperatures rise, more moisture is sucked up by the atmosphere through evapotranspiration, leaving less viable water for humans-use in the system.

A sign to stop the dam expansion in a neighborhood near Gross Reservoir outside Boulder,. (Chris Schneider, Special to The Colorado Sun)

“We are planning for infrastructure that will be built in the next 20 years, that is supposed to last for the following 100 years,” said Reagan Waskom, director of Colorado State University’s Colorado Water Institute. “Our world is changing significantly faster than that. And not in a linear way. How do we adapt to that?

“Water managers have to plan for extremes,” he added. “A year like this year is an argument for reservoirs. Even with climate change, you’re still gonna have some good years. And we need to be able to capture it and save it for the bad years, whether that’s in underground aquifers or in reservoirs.” 

But Kurtz countered that water managers and residents must look for better alternatives.

“In terms of how individual people are going to have to do things differently, we’re going to have to use less water,” she said. “We need to change our whole attitude about lots of things — but certainly in the Southwest about water. Building a bigger reservoir doesn’t make any more water.”