The Paso Robles Groundwater Basin occupies more than 500,000 acres stretching from the Highway 101 corridor to Shandon, and from Garden Farms south of Atascadero to San Ardo in Monterey County. Thousands of residents and a great deal of critical wildlife habitat depend on it. Because it is severely overdrafted, meaning groundwater is being pumped out of it faster than the rate of natural replenishment, it has been designated a high-priority basin by the California Department of Water Resources (DWR). Under the Sustainable Groundwater Management Act (SGMA), regionalgroundwater agencies for such basins are required to create groundwater sustainability plans (GSPs) and show that these plans canachieve their stated goals.

On Jan. 21, the DWR issued "incomplete" determinations on four groundwater sustainability plans. The deficient groundwater agencies were given 180 days to address the issues and resubmit their revised GSPs to the department for review.

The Paso Robles Groundwater Basin, as should surprise no one who has followed the long and tortured history of attempts to manage it, was on the DWR's do-over list. (If you didn't read "Paso basin still wishing and hoping" in the July/August Santa Lucian, go ahead and read that and come back.) DWR found that the Paso basin plan failed to adequately assess the potential impacts to domestic wells associated with the chronic decline of groundwater levels or the potential depletion of interconnected surface waters.

All the plans that received an "incomplete" have been revised and are posted on the SGMA Portal. Sept. 19 is the last day for the public to submit comments on those plans. Sometime after that, the state will render judgment.

In our remarks on the revised Paso Robles Basin Final Groundwater Sustainability Plan, the Santa Lucia Chapter of the Sierra Club and North County Watch underscored the primary deficiency of the plan.

First, there is a disaster in waiting, in the form of the county's new Paso basin planting ordinance, which, per its environmental impact report, will greatly expand pumping rights for ag zoned land in the basin via a permit to pump up to 25 acre-feet of water per year (AFY) for new plantings. As the Aug. 25 New Times reported, "Over the next 22 years, the EIR estimates it would spawn 250 new, 20-acre vineyards, which would add close to 10,000 AFY of demand on the basin—almost double what the basin's overdraft is already estimated at now."

Second, the revised Paso Robles groundwater sustainability plan, like the previous draft, doesn't acknowledge the magnitude of our current climate reality. California is in the midst of the driest year of the last 128 years, and San Luis Obispo County is in the extreme drought category ("Producers begin irrigating in the winter; ... water is inadequate for agriculture, wildlife, and urban needs; reservoirs are extremely low; hydropower is restricted").

The revised groundwater plan offers a five-year snapshot of past basin conditions and yield—missing the long-term threat of climate change and in no way a suitable predictor of the future sustainability of the basin. The plan assumes that "the estimated future sustainable yield is similar to the estimated sustainable yield for the historic base period. This similarity indicates that potential future changes in climate are not projected to have a substantial impact on the amount of groundwater that can be sustainably used compared to historical conditions."

That conclusion is possible only in the absence of a robust assessment of climate change on weather patterns and rainfall, the percolation of streamflow and precipitation, and soil aridification. That last one alone knocks the groundwater plan's optimistic assumptions into a cocked hat. As soil moisture declines, soils become less able to absorb water during rain events. As less water is retained in the soil year over year, crops will require more irrigation. Hotter summers will increase evaporation dramatically. Even with no growth in irrigated lands, more water will be required to generate the current production levels.

The basin plan claims there will be no future growth in groundwater use. Why? Because "an overarching assumption is that any future increases in groundwater use within the subbasin will be offset by equal reductions in groundwater use in other parts of the subbasin, or in other words, groundwater neutral through implementation of the GSP"—an assumption that might be correct if the groundwater sustainability plan included a one-to-one offset program to assure the neutral impacts of ag pumping in the manner of the county's soon-to-expire 1:1 offset program. But it doesn't.

The state should require a date certain, within one year of approval of the plan, by which an adequate number of monitoring wells and pumping data are in place and data is being utilized. The Department of Water Resources plans to wait until 2040 for high-priority basins to achieve groundwater sustainability goals.The basin cannot wait anywhere near that long for mandatory cutbacks to be enacted.

Decades of dithering by the county, in deep genuflection to Big Grape, have worked in tandem with climate change to make a bad situation worse. We are now in an emergency. Δ

Andrew Christie is the director of the Santa Lucia Chapter of the Sierra Club. Reach him through the editor at [email protected].