According to new research by NASA, many of the world’s biggest aquifers are being depleted at a much faster rate than they can be replenished, and California’s Central Valley is among the worst. As we all know, California is in the fourth year of an exceptional drought. When surface water supplies are scarce, we turn to groundwater. Unfortunately, our combined groundwater uses have led to chronic overdraft in many places. Like a bank account, overdraft means we are withdrawing more than we are replacing. Together, this exceptional drought along with the undesirable condition of many groundwater basins, led California to pass the Sustainable Groundwater Management Act last year. The Act is a big deal since it represents the first statewide effort to comprehensively measure and manage groundwater.
Now that the dust is settling, water users and managers are wondering: what does the Act mean for us?On Monday, UCS launched our summer webinar series on sustainable groundwater management. The first webinar discussed some of the new requirements of the Sustainable Groundwater Management Act. While I highly recommend reading the Act itself, its length (nearly 50 pages) and complexity can be a deterrent. If you don’t have the time or the inclination to read the Act, this cartoon boils down its main points pretty succinctly.
Groundwater is headed off-course: straight off a cliff
The folks in the car are listening to their G.P.S. tell them that they have arrived at an exciting destination, which happens to be straight off the edge of a cliff. In many ways, groundwater management up until this point has been a bit like this – a lot of nice-sounding objectives, but not enough specificity to avoid driving many groundwater tables off a cliff.
The box at the bottom reads: “why you need to be specific with a G.P.S.” Similarly, in order to sustainably manage groundwater, it is important to be specific. The Sustainable Groundwater Management Act requires that all at-risk groundwater basins use measurable objectives to sustainably manage groundwater supplies and avoid harmful impacts, such as chronic lowering of groundwater levels, land subsidence, and seawater intrusion. One way of thinking about this is that a groundwater plan now has to give the specific coordinates of where a groundwater basin is headed, and if those coordinates are off, or look like they may drive a basin off a cliff, the state can take the wheel.
One way to envision this “cliff” is to look at data on groundwater losses since 1962 in California’s Central Valley. While there are some jagged outcrops (brief wet periods that allowed groundwater recharge), groundwater levels drop off pretty dramatically around 1986 and again in 2007—both of which coincide with dry periods. As climate change projects more frequent, longer, and more severe drought periods, groundwater management could basically become a race to the bottom of the aquifer, if left unchecked.
Figure from UCCHM Water Advisory #1. Cumulative groundwater losses in California’s Central Valley since 1962. The red line shows data from USGS calibrated groundwater model simulations from 1962-2003. The green line shows GRACE satellite-based estimates of groundwater storage losses produced by the UCCHM. Background colors represent periods of drought (white), variable to dry conditions (grey), variable to wet conditions (light blue) and wet conditions (blue).
Steering toward sustainability: coordinates and map required
Instead, the new law requires groundwater basins be managed with a specific destination in mind (sustainable yield). It also steers us clear of dangerous cliffs (such as overdraft and other undesirable results); provides a clear map explaining how the basins will get to their destination (measurable objectives); tracks the speed they are traveling (the first groundwater sustainability plan is due in 2020, with multiple subsequent updates); and projects when improvements will arrive (sustainability must be achieved by 2040).
It seems basic, but groundwater is a complicated resource – made more complicated by the fact that people can’t actually see it, and therefore it can be difficult to realize when we are headed off of a cliff and need to change course.
As climate change warms California, we are projected to lose up to 80% of our historic snowpack. This year’s record low snowpack is a bellwether of what is to come. Sustainable groundwater management is critical to adapt to this massive loss of surface water storage. In California, it’s time to start steering toward sustainability, and we have no time to lose.
Please join us for our next two webinars on stakeholder involvement in the Sustainable Groundwater Management Act and setting measurable objectives to achieve sustainable groundwater management.