Our name is fairly simple, but our responsibilities are much more complex.

Denver Water has a duty to provide water to our customers within the city of Denver and in our larger service area, and as part of ensuring a reliable supply, we encourage those we serve to use water as efficiently as possible.

But we also promote efficiency to many areas of our state, particularly on the West Slope, where much of our water supply comes from.

And Denver Water’s efficiency ethos even extends beyond our state’s borders and into the seven-state region that makes up the Colorado River Basin. Colorado and six other states are tied together in their use of Colorado River water. (Denver Water gets half of its water supply from the South Platte River and the other half from the Colorado.)

The Colorado River Compact is the tie that binds these states together. We’ve written extensively about how and why the compact has so much bearing on Denver Water, and now we’re seeing another reminder.

Recently, the four upper basin states in the Colorado River Basin sent the Central Arizona Project a letter questioning that group’s use of Colorado River water. Denver Water CEO Jim Lochhead sent a letter as well. We talked to Lochhead to get his thoughts on how Arizona’s water use could impact Denver Water, and why water users in the seven-state basin should be paying attention. Lochhead has previously likened the situation on the Colorado River to a slow-moving train bearing down on a region of 40 million people. If we get hit, we only have ourselves to blame.

TAP: What is the Central Arizona Project (CAP)?

Lochhead: The CAP is large diversion canal that draws water from the Colorado River below Lake Mead. It delivers water to nearly 1 million acres of irrigated agricultural land in central and southern Arizona, as well as cities such as Phoenix and Tucson. The federal government releases water from Lake Mead to the CAP under a contract.

TAP: What is the CAP doing that upper basin states object to?

Lochhead: The letter questions their strategy to adjust their water demands to keep Lake Mead at a specific elevation to trigger additional water deliveries from Lake Powell. Essentially, CAP is manipulating their demands for their own benefit, while jeopardizing Colorado River water users in other states.

TAP: Why is looking at their own interests wrong?

Lochhead: In 2007, all seven basin states developed guidelines on how water is controlled from lakes Powell and Mead. Lake Powell is where upper basin states store water to send to the lower basin states to abide by the Colorado River Compact. If Powell goes too low, we can’t comply.

The guidelines were developed through a collaborative process, and they don’t contemplate one water user managing their demands to the detriment of others in the basin. They presumed all of us would be employing appropriate conservation and demand management.

Lower basin states are discussing drought contingency plans, but they haven’t reached an agreement because of internal disagreements in Arizona. During this period, CAP has been taking advantage by pulling excess water off the system.

TAP: Specifically, how could this impact Denver Water and its customers?

Lochhead: Denver Water gets half of its water supply from the Colorado River. But the compact says Colorado and the other upper basins can’t allow the flow of the river to drop below a specific flow over a 10-year running average. If that happens, potentially the lower basin states could exercise a compact call, meaning any water user who started use after 1922 would have to cease using water until the running average gets back up where it should be. In that case, Denver Water could be cut off from half of its water supply, since we developed our Colorado River supplies after that date.

TAP: How has Denver Water been trying to prevent something like that from happening?

Lochhead: We partnered with several other basin state agencies on the Colorado River System Conservation Program. The program compensates water users in both the upper and lower basins to forgo use of water and make it available in the system. The idea is to store that unused water for the benefit of all of the states in the basin. By putting this water into Lake Powell, we are depositing water into a bank account that will allow us to comply with the Colorado River Compact. By pulling excess water out of that bank account, CAP is essentially undermining this program.

This is also troubling for Denver Water because of our commitments within Colorado, particularly to our West Slope neighbors. We’ve developed partnerships with them over the use of Colorado River water. Some partners were skeptical of the System Conservation Program, so it’s important that we hold everybody involved in that program accountable.

TAP: What’s next?

Lochhead: I’m optimistic that we can have collaborative discussions with CAP, the Department of the Interior and other Colorado River basin states so we can all hold up our commitment to take proactive steps now to avoid a compact call in the future. If not, and dry conditions continue, the federal government may take unilateral actions to protect the reservoir system.

I don’t want to be alarmist, but there is a potential for problems if we run into another dry year, and if we can’t find collaborative solutions, the consequences are something we don’t really want to think about.