Almost 8 million acre-feet of water has left Colorado in the past 20 years that the state could have kept, according to preliminary data from a legislative-commissioned study expected later this year.
It’s enough to make a water warrior cry.
An acre-foot of water is about 326,000 gallons of water, or enough to satisfy two families of four every year. Eight million acre-feet? Well, you can do the math.
Historically, more of that 8 million acre-feet has left Colorado in the last 10 years. The state went through a horrific drought in 2002 and 2003, so the amount of water leaving the state leans toward the latter part of that 20-year period rather than being evenly spread out.
In a state facing a massive water shortage in the next 30-plus years, due almost exclusively to population growth, losing that much water kind of hurts.
Colorado is what’s known as a headwaters state. There are eight major river basins, with the Colorado River as the grand dame of the state’s waterways.
But as the West has grown, so has the demand for Colorado River water. Most West Slope water experts will tell you that there’s more demand for that water than the river can supply through precipitation and snowmelt.
Then there’s there’s the water demand within Colorado. Eighty percent of the water in Colorado comes from the Western side of the Continental Divide but 80 percent of the population lives east of the divide, mostly along the Front Range between Fort Collins and Pueblo.
Add into that agriculture: according to the state’s 2015 water plan, 89 percent of consumed water in Colorado goes to agriculture; municipal water needs take another 7 percent and industrial uses, including oil and gas, take the last 4 percent.
Over the last 100 years, tunnels have been bored through the mountains to bring that Western Slope water to thirsty cities and farms on the Eastern Slope. It’s a long-standing source of irritation for Western Slope folks that the Eastern Slope is taking a lot of water, with no real end in sight. At the same time, West Slope water doesn’t stay in Colorado. Most of the water from the Colorado River is required to go downstream to six other states, including to Lake Mead, a reservoir that provides water to 20 million people in Arizona, Nevada and California.
That takes us to what happened to that 8 million acre-feet of water on the South Platte. It went to Nebraska. There’s a compact, like a contract, between Colorado and Nebraska, dating from 1923, that dictates that a certain amount of water from the South Platte goes to Nebraska, which preserves the river’s downstream environment and aquatic wildlife.
The 8 million acre-feet exceeds what Colorado was legally required to send to Nebraska. But the problem for Colorado is that there’s no place to put that water.
Lawmakers and water experts have been jawing about the lost water problem for years. In 2016, Rep. J. Paul Brown of Ignacio sponsored a bill to put some teeth into the conversations, by asking how much water is being lost to Nebraska and where it can be stored.
The final answer won’t be known until the end of this year, but earlier this month, an interim water committee at the state Capitol took a first look at the data and some of the sites where storage might happen.
It’s not an easy conversation. Building new reservoirs takes decades and often has to survive lawsuits and complicated federal and state permitting processes.. Look at the Northern Integrated Supply Project near Fort Collins, which could lead to a new reservoir and expansion of a second. The project is in its 14th year and will likely take another five or six years to get through all the permitting. In the life of a reservoir, that’s short. Compare that to the Animas-La Plata reservoir in southwestern Colorado, where construction was declared finished in 2013. The project began construction in 1968.
While new storage is definitely possible for that South Platte water, other storage ideas are being considered in the study. According to Andy Moore, a senior water resources specialist with the Colorado Water Conservation Board, the state’s primary water agency, 147 sites were identified on first blush for water storage.
Those sites fall into three categories: new reservoirs, rehabilitating and/or expanding existing reservoirs, or refilling underground storage. That’s water that would be pumped into aquifers, which are underground rock formations that hold water. Colorado has four major aquifers, with the three largest all along the Eastern Slope. In 2000, the South Platte aquifer, according to the Colorado Foundation for Water Education, served about 70 percent of the Front Range population.
The site list has been pared down several times, to eliminate sites too far from the main body of the South Platte or for sites that were too small to be useful. That leaves 16 sites, mostly in northeastern Colorado. Over the next several months, those sites will be evaluated for cost, benefits and other factors.
The first look at possible storage along the South Platte was welcomed by Chris Treese, external affairs manager for the Colorado River Water Conservancy District, the water agency in charge of the Colorado. “The Western Slope has long thought that as Coloradans we’re in the water world together, but every basin should look to own resources and capabilities first before looking for outside resources,” he said.
Treese wasn’t surprised by the numbers. “This is what Brown and others in the South Platte have been saying – that it’s a problem with a suitable storage location.” He added that the study will identify whether storage is “one silver bullet or a lot of smaller opportunities.”
Rep. Jeni Arndt of Fort Collins, a Democrat who chairs the House Agriculture, Livestock and Natural Resources Committee, favors refilling aquifers first and looking at other possibilities next. Arndt sponsored a bill, signed into law this year by the governor, that allows the state engineer to set up rules for the use of water that is pumped into nontributary aquifers. Those are aquifers not connected to surface water, like rivers.
Refilling aquifers, Arndt told Colorado Politics, is environmentally friendly, with less evaporation and less permitting. It is also practical from a political standpoint, she said, meaning that there should be less opposition to refilling aquifers than to building new reservoirs.
Refilling is “appealing, makes sense, it’s cost effective and it’s politically doable,” she said.
Brown was pleased with the study’s first data.
“This is the kind of information needed to make good decisions about what to do on the South Platte,” he said this week. He pointed out that the Arkansas, Rio Grande and Colorado rivers all have instream storage, and the only place without it is the South Platte.
For years, “the low-hanging fruit has been West Slope water,” Brown explained. And while Colorado has always delivered its Colorado River water as it should under the compact, the supply is just not there anymore. “It’s not just a West Slope issue – it’s an issue for the entire state. People who know water are very interested in making sure we don’t waste any and don’t send any more water to Nebraska than what they’re entitled to.”