While waiting for the Arkansas Valley pipeline, Las Animas and La Junta rely on reverse osmosis for clean drinking water

DENVER — Las Animas and La Junta boast of having the best drinking water in Colorado’s Lower Arkansas Valley, a region long known for its water challenges.

Like dozens of communities along the river, the two towns rely on groundwater contaminated with salts, iron, manganese and PFAS, also called “forever chemicals.” Other towns draw from deep wells, which carry naturally occurring radioactive elements. Las Animas and La Junta found a solution to this water challenge with reverse osmosis technology, a decades-old investment that’s providing clean drinking water as residents wait for the completion of the Arkansas Valley Conduit.

Since 1962, dozens of towns in southeastern Colorado have waited for the 130-mile pipeline meant to deliver clean drinking water, but the federal project stalled for decades and is still years from completion. 

“It gets to a point where you can really only wait for something for so long,” said Tom Seaba, director of water and wastewater treatment for the City of La Junta, about the pipeline. 

While reverse osmosis in Las Animas and La Junta has provided clean drinking water, experts say it’s not a permanent solution because it requires waste to be discharged.

La Junta’s reverse osmosis plant went online in 2004, while Las Animas began using the technology in the mid‑1990s as part of an economic development project that helped the town secure funding for a water treatment facility.

Anthony Philip Straub, a former researcher on water treatment and sustainable energy at the University of Colorado Boulder, said reverse osmosis is a useful technology for treating water with high salinity and other contaminants.

“But with reverse osmosis, one of the main downsides … you're pushing water through this membrane and you can't push all of it through because you're rejecting the salts and other contaminants … what we call brine,” Straub said. “And so depending on where they're discharging the brine water, it can affect the water quality.”

The brine, or salty wastewater, from both towns’ reverse osmosis systems is dumped back into the Arkansas River, creating a new environmental challenge.

“We have probably the best water in the Arkansas Valley right now, but the reverse osmosis operation cannot be a long term solution,” said Bill Long, a Las Animas resident who also serves as president of the Southeastern Colorado Water Conservancy District. 

Long said this is why the town remains dependent on the unfinished Arkansas Valley Conduit. The pipeline would deliver clean water straight to the town, requiring only standard treatment like filtration and disinfection. The future of the conduit, however, remains uncertain. Currently, there is enough federal funding for the pipeline to stretch from Avondale to Mazanola, Colorado, which is about half of the planned length. Under the current appropriations, the pipeline would not reach La Junta and Las Animas, which are farther east. 

Efforts to secure more support for the project ran into a roadblock after President Donald Trump vetoed the bipartisan “Finish the Arkansas Valley Conduit Act” on Dec. 31, 2025. The bill, sponsored by Colorado Rep. Lauren Boebert, a Republican and longtime Trump supporter, would have eased the local share of the project’s costs — currently split 35% local and 65% federal — by cutting the interest rate in half and extending the repayment term from 50 to 75 years. Congress voted against overruling Trump’s veto.

“Our hope is that as those projects get completed, more money will become available,” said Chris Woodka, senior policy and issues manager for the Southeastern Colorado Water Conservancy District. 

Las Animas is currently allowed to discharge the contaminants removed by its water treatment plant into the Arkansas River, with the commitment to eventually correct the issue, Long said.

“There is a requirement to discontinue that practice,” he said. “And the only way to correct the discharge problem is to have a cleaner source of water.”

Towns can discharge into the Lower Arkansas River as long as they stay within the limits of Colorado’s water quality standards.

Straub said there are ways to treat the brine so that liquid discharge is completely eliminated through a process called “zero liquid discharge.”

“It is basically the idea that when you're treating one of these saline waters, you can take that brine stream and further treat it to the point where you just have a solid come out,” he said. “The issue is it tends to take a substantial amount of energy and cost. As you get a more and more concentrated brine, it gets more and more costly to treat it.”

Zero liquid discharge systems can cost millions to install and even more to operate, and are very energy‑intensive. But the byproduct comes in a much smaller volume and mass, making it easier to manage, Straub said. It can be sent to landfills or injected underground, he said. 

For now, the reverse osmosis system is what allows residents of Las Animas and La Junta to get clean drinkable water that they otherwise would not have. 

Seaba said the City of La Junta is currently applying for grant opportunities to rehabilitate their plant to better treat PFAS and selenium concerns. 

“Through the rehabilitation of our plant, we hope to install newer, more efficient osmosis treatment trains that can reduce the volume of concentrate significantly so that the waste flow is reduced a lot and is more easily either treated or removed off site for treatment,” Seaba said. 

In Las Animas, clean water comes with relatively high water bills that residents must pay, which can be a heavy burden in a high‑poverty, economically depressed area, Long said. 

Both towns say they must find a sustainable solution that handles wastewater without further harming the river’s quality. 

“The only realistic solution to our problem at the wastewater plant is a cleaner source of water and the cleaner source of water is not in the river,” Long said.