Denver Water Preps for Population Boom

A proactive multipronged approach will help Colorado's oldest and largest water supplier meet the needs of its customers for decades to come.
Denver Water Preps for Population Boom
Bob Peters, water resource engineer at Denver Water, has spent the last two years planning and executing aquifer storage and recovery site testing.

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The Mile High City has its fair share of water-related challenges to contend with as it envisions a future filled with more Coloradans. Denver Water — Colorado’s oldest and largest water utility — is on the forefront of that battle.

The agency serves approximately 1.3 million people in Denver and the surrounding suburbs and expects that figure to explode in the years ahead.

“On the statewide level, the demographer is expecting that our population will double or nearly double by 2050,” says Greg Fisher, Denver Water’s manager of demand planning. “We’re going to add about another 5 million people to Colorado, and a good number of those people will move into the Denver Water area.”

Population growth is just one of a whole assortment of challenges to contend with while addressing long-term planning. According to Fisher, there’s a need to prepare for factors such as climate change, alterations in water-use patterns, economic irregularities, government regulations, droughts and more.

As the agency continues to hone in on water sustainability, its comprehensive approach includes conservation, reuse and new sources of supply and storage.

“It’s really the recognition that no single strategy will provide the solution for meeting our customers’ needs 40 or 50 years out,” Fisher says. “What we really need to do is diversify our solutions in order to meet a lot of the objectives that we have.”

Exploring alternatives
Part of the diversification strategy has included the study of new and alternative options, such as the underground storage of water in aquifers. By injecting water during wet years and storing that supply, water can later be extracted during times of need.

“Right now we rely 100 percent on surface water for our supply,” Fisher says. “Having the ability to store some excess water underground in wet years would really help diversify and reduce some of the vulnerabilities we have from full reliance on surface supplies.”

Several properties in the Denver metro area have been accessed in order to drill exploratory boreholes and collect data on the underlying aquifer. The purpose is to gain a better understanding of the storage potential within Denver Water’s service area.

“We’re trying to take this step by step,” Fisher says. The first step is to figure out the storage capacity of a well then test it to see if the water moves or goes away. After that, there would be a need to understand how to bring that water back up, determine how much treatment it would need, and figure out where to hook back into the distribution system.

Much of the borehole investigations were handled last year and are expected to continue in 2016. At the end of the year, Denver Water intends to evaluate whether or not it makes sense to move forward with a pilot well.

Expanding sources of supply
Denver Water has worked to expand on its existing sources of supply in other ways as well. The Downstream Reservoir Water Storage Program enables the agency to store and release reusable water in its system through the use of old gravel mines. These pits store water used for exchange purposes, and the system has been evolving from three different complexes in order to meet an identified need for roughly 30,000 acre-feet of storage.

The South Reservoir complex, which stores about 3,200 acre-feet, has been mined and lined and is fully operational. The North Reservoir Complex is fully mined, and Denver Water is anticipating the ability to carry out gravity operation for a number of years that would allow for about 2,300 acre-feet. “Eventually we’ll put in a pump station and then have access to the full 17,000 acre-feet in that complex,” Fisher says. It will be several years before the third complex is operational.

Developing new supply in the Moffat Collection System is expected to nearly triple the capacity of Gross Reservoir and address the area’s impending supply shortage while improving the reliability of Denver Water’s system. A cost estimate of $360 million includes the design, management, permitting, mitigation and construction expenses.

The Downstream Reservoir Water Storage Program, which has been in the works since 1997, allows Denver Water to store and release reusable water in its system through the use of depleted gravel mines that have been improved to store and release water.

Conservation and recycling efforts
The agency’s conservation program includes rebates and incentives for residential and commercial customers, summertime regulations to reinforce best practices for outdoor watering, requirements for new properties to alter soil in order to retain more water, tiered water rates and more.

“We are on the back end of a very aggressive 10-year conservation program,” Fisher says. “Our board asked us 10 years ago to reduce customer use by 22 percent within 10 years. We have been meeting and exceeding that within the last few years.”

The reuse of water is another key element of the whole multipronged approach. With a system that’s been in place since 2004 and produces an average of 2 billion gallons of recycled water on an annual basis, it uses include both irrigation and industrial.

The Denver Zoo, the Denver Museum of Nature and Science and Xcel Energy are all notable beneficiaries, and there are plenty of others. “We have over 88 customers throughout the Denver area and Adams County that utilize recycled water — mainly for irrigation,” says Reusable Water Program Manager Brenley McKenna.

In the near future, water will also be delivered to The Rocky Mountain Arsenal National Wildlife Refuge to keep its lakes full.

Integrated approach
Yet another fresh concept being pursued at the moment is One Water — an integrated and sustainable approach to water management that looks at each aspect of the water cycle and the value of watershed within an urban environment.

“This looks to employ green infrastructure and resource recovery, and it looks at all the different integrated approaches to water supply,” McKenna says, “so not only recycled or reclaimed water, but graywater usage, on-site treatment, groundwater, rainwater, stormwater, and these other supplies.”

The hope, she added, is that this will help close the water supply gap heading into the future.


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