Groundwater Sustainability Agencies still unsure over monitoring, nearing draft sustainability plan
Greater Kaweah intends to achieve five percent of sustainability plan over five years, growers encouraged to track groundwater use
By Paul Myers @PaulM_SGN
EXETER — Measuring the water beneath our feet takes technology that looks out of this world, and pictures that actually are.
As the deadline for sustainable groundwater plans draws near agencies in charge are looking to NASA, foreign governments and top universities to figure out how much groundwater we have and how much we can use.
Since California’s Sustainable Groundwater Management Act (SGMA) was signed into law in 2014, it has been a mad dash to identify what is sustainable. Five years later, Greater Kaweah Groundwater Sustainability Agency (Greater Kaweah) general manager, Eric Osterling says that things are getting clearer as their Groundwater Sustainability Plan (GSP) comes into focus.
Draft GSPs are slated to come out this summer and as of now the Greater Kaweah and other GSAs were able to identify that the Kaweah sub-basin—one of the most critically over drafted sub-basins in California—has an average annual overdraft of 78,000 acre feet. The Greater Kaweah’s portion of that is 42,675 acre feet. Considering that agriculture is the core of the local economy, Osterling says they cannot implement 100 percent of their plan on day one.
“We’re taking a very conservative approach to make sure we are not overshooting the objective,” Osterling said.
With much to be reconsidered and reviewed as the Greater Kaweah holds public meetings over their GSP before the official finalization by Jan. 31, 2020, Osterling says their plan is to achieve 5% of their plan in the first five years to put 2,134 acre feet back into the aquifer.
The first 5 percent in the first five years does little to impact individual pumpers. Instead of focusing on individual well owners, the Greater Kaweah’s main focus is to address recharge projects.
“Recharge is critical. Some of the oldest recharge programs reside here in the Valley” Osterling said.
He added that the Greater Kaweah could put an emphasis on projects like increasing ponding basins to capture more water that would otherwise runoff. But to save on large land purchases they could also institute a recharge incentivization program for growers. Osterling said the Greater Kaweah would work with farmers to offer them surface water at a reduced cost to over irrigate to sink the water into the aquifer.
“For a fraction of that cost you are working with the grower to help spread some of that water out,” Osterling said.
While sustainability is key to satisfy SGMA requirements, GSAs like the Greater Kaweah still have to avoid undesirable results like poor water quality, chronic lowering of groundwater elevation, chronic subsidence, and damage to groundwater dependent ecosystems. Chris Johnson Founder and principal hydrologist with Aegis Groundwater Consulting from Fresno says it is a mystery about how the State’s says it is a mystery about how the State’s Department of Water Resources might take over if undesirable results occur.
“As much as we don’t want big government, if they don’t feel that we are doing a good job of managing this resource, they’ll do it for us. How so is hard to say,” Johnson said.
In a new SGMA world one thing is clear, GSAs will have to find a way to monitor the water that is coming out of the ground. For individual pumpers the future is uncertain, which is why they are being encouraged to mine their own data now.
Data is king
Three weeks ago when ag professionals and SGMA experts convened at the Exeter Memorial Building there was a lot to take in. But the most useful information that might help growers dependent on groundwater can be collected by themselves.
It is the job of a Groundwater Sustainability Agency (GSA) to measure the water below the ground, and how to make it sustainable. The problem is that measuring water in the underground basin is not a perfect science.
“GSA’s are struggling with the fact that there is not that much information so they are making assumptions,” Johnson said.
If growers have to defend their usage, Johnson says it is best to have the concrete data to back it up. In terms of clients, Johnson said that approximately 50% of them at one time or another had no instruments telling them the static water level, pumping water level, or drawdown. And then there is the outstanding question about whether the gauges are appropriately calibrated to give accurate readings. Which Johnson says is a common problem. He added that too often growers drill a well and put a pump on it and then forget about it till it breaks.
“Out of site out of mind. It’s metal, with time it rusts, natural minerals will plug it up, if you don’t maintain it you’ll spend a lot of money. So, maintenance is important,” Johnson said, and then likened it to a car. “You’d never know if your car was getting bad fuel economy without gauges.”
Without accurate well data pumpers would be left in a vulnerable position if GSAs are forced to limit the amount of water growers can pump and then force them to meter their pump at their own cost. Data is helpful because it can challenge a GSA’s assumption. Groundwater Sustainability Agencies may be deriving their groundwater measurements from an index well, or taking an average from a sample size of all wells in the GSA. The GSAs could then use those measurements to determine sustainable groundwater levels.
Johnson says that growers who do not think their well is reflective of an index well or average will best be able to argue their point with their own data. In some cases, the data might show that a grower was not over pumping, or should be allotted more acre feet.
“It’s a position of defensibility,” Johnson said.
For GSAs like the Greater Kaweah, trying to determine a starting point has taken some serious effort.
“Everything beneath our feet is a black box. But we do have data points and there are ways to fill in those points with facts,” Osterling said.
Thanks to efforts from Stanford University, the Danish Government and the US National Aeronautics and Space Administration (NASA), the Greater Kaweah was able to deploy some cutting-edge technology to study the sub-basin. Perhaps growers or others around Tulare County noticed space age looking material flying around the sky last November. Well, it wasn’t anything out of this world that will help find sustainability in the water basin, but helicopters dangling sizable hexagons 100 feet above the ground have helped measure what is below the surface.
SkyTEM, meaning Sky transient electromagnetic technology works most similarly to sonar. It has helped create 3-D models of the basin going down as much as 80 feet, and Osterling says this level of tech can help well owners.
“SkyTEM gives us a tremendous amount of information into our model…and helps people installing new wells so they can have better certainty about where they are going to place it and be spot on,” Osterling said.
As for metering individual wells, Osterling says that it’s too early to tell if they will have to. He added that metering every well in the Greater Kaweah, much less the entire sub-basin, is an expensive way to go. Another option is to actually go out of the world. Osterling says that a much more affordable option is to measure evapotransporation from satellites in space, which is what they are currently doing.
The Kaweah Delta Water Conservation District has been contracting with a firm called David’s Engineering that offers remote sensing solutions. They use government satellites that allow them to judge how much water is applied to vegetation in the area. Shortcomings are that its sensors cannot tell what the crop is, nor can it tell whether the water came from the surface or the ground.
Osterling added that the Greater Kaweah has been fortunate in the sense that they do not have to aggressively meter the water taken out of the ground. At least not yet. While everyone understands the danger subsidence has on infrastructure, the three GSAs that predominately cover the Kaweah sub-basin do not have structural deficiencies encumbering urgent solutions. Osterling says GSAs in the Tule sub-basin has been forced to move right to metering.
“There is nothing currently that we are as concerned about as the people in the Tule [sub-basin] are with the Friant Kern Canal,” Osterling said.