Tapped: The Denver metro region sits at the center of one of the American West’s most complex and consequential water challenges. This series examines the interconnected systems that determine how the region secures, stores, and conserves its water while navigating the competing demands of fast‑growing urban communities and the increasingly unpredictable mountain snowpack that underpins the entire system.

In a community that’s no longer growing outward but facing a hotter, drier future, Highlands Ranch Water is turning to deep conservation measures to stretch its supplies and steady a system increasingly shaped by climate pressure rather than population demand.

“Research shows that it’s going to get hotter and drier, and we’re going to continue to have conditions where the water supply is not great, and we have to be ready to deal with that,” said Sam Calkins, general manager for Highlands Ranch Water. 

Calkins said drought planning and conservation have been long-standing priorities. Following the 2002 drought, the district implemented water budgets that cut usage by about 20%. Even as the population doubled, total water use increased by only about 50%.

“Over time, those water budgets allowed water use to increase by about 50% while our population doubled,” Calkins said.

Like other providers in Douglas County, Highlands Ranch Water relies on nonrenewable deep aquifers and renewable surface water from rivers. 

On average, 85% of the community’s water comes from surface water, sourced from the South Platte River and the WISE partnership, annually, with groundwater used primarily as a backup supply. HRW captures approximately half of that surface water supply for reuse.

“When we release water into the South Platte River, we can either pull it out of the South Platte with our alluvial wells or exchange it in Chatfield Reservoir,” Calkins said. “That reuse is critical to us.”

In addition to seeking additional water rights, storage expansion and source diversity, HRW is pushing toward conservation as a means toward sustainability. In the largely residential development, outdoor irrigation accounts for about 49% of consumption, representing the largest opportunity for reductions.

“That’s people keeping their lawns green. We think that we can get a 20% reduction in outdoor watering just through conservation efforts relatively easily,” Calkins said. 

To support those reductions, the district offers incentives including turf replacement, smart irrigation controllers, high‑efficiency sprinkler nozzles, rain sensors, and rebates for water‑efficient fixtures

The water authority’s goal is to reduce the total water demand between 5% and 10%

“The current outlook is certainly driving us towards the need for more water supply and investments, but the bigger focus for us is on conservation,” Calkins said. “Through conservation, I’m confident we can really make the supplies we do have last a lot longer and meet our future needs.” 

Highlands Ranch Water’s long-term plan focuses on increasing storage opportunities to capitalize on wetter years. During the summer, user demand can reach 35 million gallons a day. In conditions like those the region is currently facing, Calkins said the district will still be able to use groundwater from aquifers. 

“You don’t want to have a system that’s forever reliant on groundwater because it’s a finite resource,” Calkins said. “But if you manage it strategically in years when there’s not a lot of natural stream flow, you can supplement your water supplies with groundwater, and use it sparingly as needed.”

The water authority is currently increasing the capacity of its surface water treatment plant, which will be able to meet HRW’s total demand when water is available by 2030.

“A huge part of being able to weather these dry years is having sufficient storage. You can fill it up in wet years and then use it slowly over time,” Calkins said. 

Additionally, HRW is part of an aquifer storage and recovery program that involves injecting treated surface water into deep aquifers, thereby reducing net groundwater withdrawal. Highlands Ranch has, to date, injected more than 15,000 acre-feet of water into 25 wells, replacing a portion of the groundwater that has been withdrawn.

While the district is currently under drought stage one status, restricting outdoor irrigation, it has a plan for drought conditions, including potential special drought rates.

Calkins said that, even with the current water supply outlook, given current usage in Highlands Ranch, he expects the district can still meet future demand through conservation. 

“In the worst case, we could exist on half the water that we have now if nobody watered any grass, at least in Highlands Ranch,” Calkins said. “If you look at the worst-case scenario, we survive without green grass.”