Ever since we saw early glimpses last spring of data from Stephanie Castle, Jay Famiglietti and colleagues about groundwater depletion in the Colorado River Basin, I’ve been puzzling over the policy implications. Their data, published today in GRL, is worth an “OMG IT’S WORSE THAN WE THOUGHT!” While we’ve been watching Lake Mead’s bathtub ring grow and the basin has lost 12 million acre feet of stored surface water in the last decade, aquifers have declined more than 40 million feet, essentially unnoticed.

In a fascinating talk in the spring at the Bureau of Reclamation, Oregon State University’s Aaron Wolf, the guru of water conflict (or lack thereof) explained how his data showed collaboration and cooperation is far more common than fighting over water. The key thing to look for is how a basin’s water users are able to respond to change. Change can be abrupt, like flooding, or drawn out, like drought or the sort of inexorably rising demand that we’re seeing in the Colorado Basin. Actually, we’ve got drought too, so check that off. At this point you look to institutions:

There’s change in the basin. All the things you look for. Scarcity, floods, droughts, economic growth, tensions. Everything that’s going on. Managing that is a certain level of institutional capacity. How good are the agreements? How good are the relationships? How well do they work together? That helps mitigate the change…. The likelihood of conflict rises as the rate of change in a basin exceeds the institutional capacity to absorb the change.

Pumping groundwater in the Colorado River Basin, March 2014

I’ve been arguing that one of the things we see in the Colorado River Basin is an institutional maturity that has thus far had the ability to absorb the changes we’ve seen to date – the 2001 Interim Surplus Guidelines that jiggered Colorado Basin allocations to rein in California’s overuse (pdf), the 2007 shortage sharing agreement, the remarkable Minute 319 deal with Mexico. Those institutions are now wrestling with the fact that none of this has been enough, which is why maybe this week we’ll see the announcement of a system conservation program deal that will be one more brick in that wall.

All of that shows the maturity, I think of basin-wide water management institutions. Only time will tell of that’s enough, but it’s the sort of thing Wolf’s research shows is a necessary precondition to success. But all of those institutions deal with surface water. What Castle and colleagues are pointing out is that groundwater drawdown is a huge unaddressed problem. And we’ve got no basin-wide institutions for that.

Maybe we simply don’t need them. One of the core principles of basin management is that we need these institutional arrangements because the Colorado River and its tributaries flow alongside or through nine different states. One of the key institutional approaches has been to set allocations at the states’ borders and leave each state to deal with its own internal allocations within its own state-by-state institutions. That’s where groundwater institutions lie. Each state has its own (and they’re widely varied – in preparing for this post I found a few reviews explaining how each state handles its own groundwater, and for now I’ll just categorize them as “tl;dr” – too long, didn’t read :-).

The short answer, then, is that if an individual state has permitted overpumping, that state is going to have to deal with the consequences. This isn’t a basin-wide problem, so much as seven individual problems, for seven individual states.

But even if that assessment is correct, it still becomes a basin-wide problem if groundwater problems at home make it more difficult for the states to make the water-sharing and curtailment decisions that are going to be needed to cobble together overarching solutions to the Colorado River Basin’s problems as a whole. Does groundwater depletion add a level of difficulty that exceeds our institutional capacity to absorb change?

What Castle and her colleagues have given us is enormously helpful, but it’s only the start. It’s gross data. To understand the implications, we really need to drill down now to a much more local level – who’s doing all this pumping, where, and what are the implications at a zillion local watershed scales?

That’s how we’ll figure out where we are on Wolf’s scale of institutional readiness to deal with a problem that’s bigger than I thought it was before I saw this data.