The risks of overestimating future water demand

Laura Paskus has a new piece touching on an issue that is one of the most important policy problems in western US water management – the tendency of water managers to overestimate future demand. In this case, it’s the Gila River basin in southwestern New Mexico, where planners are considering significant investment to build a new water diversion for use by the region’s communities. But will that water be needed in the long run? She’s quoting here Craig Roepke, prior to his retirement as the state of New Mexico’s manager for the Gila project:

But before the engineers laid out planning options for the board to consider, Craig Roepke, the New Mexico Interstate Stream Commission’s Gila Region Manager, set the stage. His remarks focused on the demand for additional water in the region. On a screen at the front of the room, he showed that water demand ranged from 45,000-160,000 acre feet of water (slide nine in this  PowerPoint presentation).

Roepke called it a “rough cut” estimate of water needs in southwestern New Mexico.

“It doesn’t matter where you put a project or what it would be,” he told the board members. “Even if you could develop every acre of AWSA water, you couldn’t ever meet needs, even in any particular basin.”

That’s a lot of water needed. But when Laura dove into the details, the ISC could come up with no data to support those numbers, and, as she explains, there is some doubt that that much water will ever be needed.

As I wrote last summer in a piece for the Breakthrough Journal, we have a long history of overestimating future water demand and therefore overbuilding water infrastructure in response. This is a problem.