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Blog Post · October 1, 2018

Groundwater and the Colorado River

The Colorado River

Like so many rivers, the Colorado is closely linked to groundwater. A US Geological Survey study found that more than half of the streamflow in the upper Colorado Basin originates as groundwater.  We talked to Doug Kenney—director of the Western Water Policy Program at the University of Colorado and a member of the PPIC Water Policy Center research network―about managing groundwater in the basin. Kenney organized a conference in June that covered these issues in depth.

PPIC: What is the status of the basin’s groundwater?

Doug Kenney: That’s difficult to answer, in part because there’s a lack of good information on groundwater in many areas. Also, there is no one groundwater source—the Colorado Basin has multiple aquifers, with different types of connections to surface waters and different uses for the water. Some aquifers provide potable water, while others are too salty or polluted to use for drinking. We have a number of huge aquifers, and some very tiny ones.

Some places have a very tight physical connection between groundwater and rivers. In those areas, if you drill a lot of wells and the water table drops, streams can dry up. The connection goes the other way as well—when there’s a lot of water flowing in streams, some seeps into aquifers. In other places, there may not be a physical connection but groundwater use impacts overall water management. The key is that if you manage groundwater poorly, surface water will ultimately suffer―and vice versa.

PPIC: What are the big challenges for managing groundwater in the basin?

DK: While it’s hard to generalize, the trend is increased pressure on groundwater, just as with the basin’s surface water. In some aquifers, depletion is a really acute problem. The management challenge is that with so many differing circumstances, you need a unique approach for each one. Each state in the basin has come up with its own groundwater laws and policies, but each state also recognizes that managing groundwater at the state level is too broad―you still need solutions tailored to local conditions.

Managing groundwater is just inherently difficult—you can’t see it and it’s hard to measure. And there’s a time lag: bad groundwater management today often creates slow-moving problems that might not be felt for many years. In those cases, there’s no constituency to protest groundwater mismanagement because those constituents haven’t been born yet. With surface water, if someone is using water in a way that harms another user, that user will draw attention to the problem.

The Colorado River is governed by a compact between states, and there’s a body of law to help manage its surface waters. But the river’s compact doesn’t deal with groundwater, and it’s always been left out of the discussion. You can get away with that for a while, but once it affects surface-water allocations, that’s where agreements start to fall apart—as has happened on the Rio Grande, the Arkansas, and the Republican Rivers. These are just three examples where the Supreme Court had to get involved. I worry that’s going to be the future for the Colorado too.

PPIC: What strategies hold promise for improving groundwater management in the future?

DK: I’d say 80% of good groundwater management is just making the effort. It will always be a difficult endeavor, but you have to try.

In many respects, groundwater management has become more innovative than for surface water. For example, there are more experiments with market-based approaches in groundwater. In places as diverse as the Diamond Valley in Nevada and in the San Luis Valley in Colorado, new incentive structures are being tried to reward people for not depleting the aquifer. In both places, prospects for maintaining the agricultural economy are much better than before; people have had to innovate or die. In surface water, it’s more about clarifying who has what rights to water and enforcing them—there’s not as much innovation. But in groundwater people are trying creative things and it’s encouraging.


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