If you want to really understand the scope of California’s water problems you have to look beyond the snowpack and reservoir measurements. Or really, below them, to our groundwater resources.
We now know that we’re depleting groundwater in many areas faster than it can be replenished by nature or ourselves. No one knows this better than hydrologist Jay Famiglietti, the senior water scientist at the NASA Jet Propulsion Laboratory (JPL) at the California Institute of Technology and a professor of Earth System Science and Civil and Environmental Engineering at the University of California, Irvine.
Famiglietti is among a team of researchers at JPL who have been using satellite hydrologic monitoring to understand changes in the earth’s water, including underground. Their research relies on the Gravity Recovery and Climate Experiment (GRACE) mission, which gathers information from two satellites orbiting the earth at about 249 miles (400km).
As the satellites fly over an area with more water mass on the ground, the region creates a greater gravitational tug on the satellites and pulls them closer to the earth by just a few millimeters. The opposite happens if they orbit over a place, such as California’s Central Valley, that has lost water mass because of groundwater depletion. In that case, the satellites orbit just a bit higher.
Famiglietti describes the GRACE system as being like a scale in the sky. What it measures is subtle yet immeasurably important. The team’s work has tracked critical water losses to major aquifers across the world, including here in California.
Water Deeply recently spoke to Famiglietti about what his research has uncovered and what it means for California’s water future.
Water Deeply: The GRACE mission measures a change in the amount of water, but not how much water is in our aquifers, right?
Jay Famiglietti: That’s quite right. It should give us the delta and it gives us the change in the total amount of water stored all lumped together – the surface water, the soil moisture, the groundwater and the snow. That’s part of the research we have to do – figure out how much is snow, how much is groundwater, etc.
Water Deeply: Do we have a good understanding of how much groundwater we have in places like the Central Valley?
Jay Famiglietti: No. We really don’t. Those measurements have never really been made. There are some very old numbers that are floating around in some old USGS [United States Geologic Survey] reports, but when you read the details very carefully you realize no one ever made the measurements and it’s just really anyone’s guess.
Water Deeply: But it’s possible to measure that, right?
Jay Famiglietti: Well, sure, we could drill it. We could explore it the same way we explore oil reservoirs. But we haven’t done that with water for many, many reasons. The value isn’t high enough to make it worthwhile and the population hasn’t been big enough and I think we are just getting to the point now where we think “Jeez, we better tackle this problem.”
Water Deeply: You’ve found a number of the world’s largest aquifers are being depleted. One of these is right here in California in the Central Valley. What’s happening there?
Jay Famiglietti: The pattern that we follow in the Central Valley is the same one we follow all over the world, which is that in wet years we use less groundwater and in dry years we use a lot more groundwater. And when you add up those wet versus dry years over time in places like California, it’s mostly dry. So we are mostly depleting the groundwater and that groundwater has been in long-term decline, basically since the day we started pumping it.
These past few years have been pretty rough for the aquifer. It kinda doesn’t really make sense to talk about it being the lowest ever because every time it gets lower, it’s the lowest ever. There are the subsidence issues happening in some places, the quality of the water is degrading and the cost of drilling the deep wells – we’re talking now on average of $250,000 to $300,000. So of course that is expensive and there are not many people who can afford that.
We are already seeing these social inequities.
Water Deeply: California finally passed the Sustainable Groundwater Management Act (SGMA) in 2014 but it will take decades to implement. Do you think it goes far enough and fast enough considering what you know about the scale of the problem?
Jay Famiglietti: I’m certainly glad it passed and there is a lot of flexibility in it. I don’t think a more detailed bill would have passed. So, in that sense, I’m glad that we have it. But no, it leaves a lot of questions and implementation details undefined.
And the one thing that really concerns me is some regions have up to 27 years to come into compliance with their sustainability plan. Also, it is difficult to define what we mean by sustainability. I think we’re beyond the point of classic sustainability, which is that we don’t use more groundwater than is being recharged each year. I don’t see that happening. We can’t sustain agriculture. So then what does that mean for managing water? What I think it really means is a managed rate of depletion and no one is talking about that.
The other thing is that 27 total years is a long time and if we really don’t get our acts together, I’m afraid there won’t be any groundwater left to manage.
Water Deeply: Do think California’s water rights system will be difficult in trying to regulate groundwater?
Jay Famiglietti: I think so. I think that governance is an issue all over the world. Most of it is really inconsistent with our current understanding of how water moves over and through the land. So it’s a real obstacle to sustaining groundwater for the long term.
I don’t have much hope we’re going to change it. I think that we are headed for the Cliven Bundy scenarios if we start talking about changing water rights. I think people will dig in and it will be an “over my dead body” situation.
When you put it all together and you think about the governance and you think about the need to grow food, and the lack of teeth in the governance and the long time scale of SGMA, I’m not terribly optimistic about the future. I hate to say that, but it’s just the way it is.
Water Deeply: What should we be doing?
Jay Famiglietti: I think we need to be managing surface water and groundwater together – conjunctive water use. I think we just kid ourselves when we cut back on the surface water allocations. It doesn’t save total water because we just use more groundwater. We basically manage surface water and forget about groundwater. We have to get over that because we are using it up.
Socially, the biggest use of water is for agriculture. We really need to be thinking about how to grow food more efficiently. Maybe California is the right place to do it and maybe it isn’t, I don’t know. But those are societal decisions that we are going to have to make. Certainly we need far greater efficiency.
Individually, the biggest use of water is the grass. At least in the southwest, we have to get over having the green lawn, it sucks up so much water. If everybody converted to native landscaping I’m sure we’d buy ourselves a few decades of water supply, if not more.