Daniel Rothberg yesterday published a very helpful Q and A with John Entsminger of the Southern Nevada Water Authority that gets to the heart of one of the really important discussions now underway in the Colorado River Basin:
Rothberg: You mentioned not that long ago, testifying in Congress, that “the river community is far from a consensus about how dry of a future to plan for.” What are some of the differing opinions right now? And where are people on establishing that baseline of what the future looks like for the river?
Entsminger: I was on a panel at the University of Colorado Law School within the last six weeks or so. And a couple people on the panel were asked that question of how dry a future should we be planning for, and I said I thought an 11 million acre-feet annual flow of the river is probably a good place to start based upon what I’ve heard from folks like Jonathan Overpeck and Brad Udall and other smart climate scientists.
But there were some folks on that panel that threw out a number of 13 to 14 million acre-feet, which, frankly, is quite a bit more water than the average of the last 20 years. So I think just from that exchange, you can see that there isn’t currently a consensus on what sort of worst-case scenario should we be planning for, as we negotiate operating guidelines for post-2026.
By way of context, we’ve had a ~12.5 million acre foot river for the past two decades, with climate change researchers (cue Brad Udall) suggesting we should expect lower flows in the future.
Entsminger didn’t name names in the Rothberg interview, but for completeness sake it is worth sharing in full the comment to which he is referring, given how it has echoed around the Colorado River Basin governance community in the last two months. I avoided writing about it at the time because, as the panel’s moderator, I wasn’t taking careful notes. But the video’s posted and I’ve had time to go back and give it a careful listen.
It came from New Mexico State Engineer John D’Antonio (the key bits from John D’s comments start here at around 16:40), in implicit response to the argument Entsminger and others have been making about the need to consider low-flow scenarios. Such low flow scenarios, D’Antonio said, would leave Upper Basin plans for new water uses above and beyond what they’re currently taking from the river “high and dry”:
13.5 million acre feet, 14 million acre feet is a little bit more realistic. I get it, it’s not there now. But it could be there.
At the Boulder conference, Entsminger made the argument (an argument with which I agree) that a range of planning scenarios is appropriate. In fact, he argued, 11 maf may not be dry enough, but it may be the biggest drop that we can realistically hope to get the political support needed to develop a plan for. To the extent that D’Antonio’s comments are representative of any broader Upper Basin sentiment, even 11 maf may be a heavy lift.