To avoid state intervention, Stanislaus County OKs plan to reduce groundwater pumping
County supervisors on Tuesday approved a groundwater pumping reduction plan for an area in Stanislaus’ West Side in hopes of preventing intervention from the state.
The Delta-Mendota Groundwater Subbasin is considered to be critically overdrafted, according to the California Department of Water Resources, raising concerns about ground subsidence near the Delta-Mendota Canal and California Aqueduct.
Affected parties in the Delta-Mendota groundwater subbasin, in west Stanislaus and Merced counties, developed six coordinated groundwater sustainability plans, which were deemed incomplete by the state after a two-year review and declared inadequate after amendments were submitted to address deficiencies in 2022.
Faced with a perceived three-strikes rule, the local agencies decided to work with a consultant on a single plan for reduced pumping, along with well metering and monitoring, which was approved by Stanislaus supervisors Tuesday.
The State Water Resources Control Board could hold a probationary hearing on the state of the groundwater basin before June. Local entities like the Del Puerto Water District, West Stanislaus Irrigation District, Patterson Irrigation District and city of Patterson want to keep managing groundwater in the area for crops and municipal use.
California began an era of groundwater regulation when former Gov. Jerry Brown signed a package of legislation in 2014. Today, Stanislaus County has four Groundwater Sustainability Agencies requiring local agencies to manage the groundwater beneath them under close scrutiny from the state. The agencies include the Modesto, Turlock, Eastern San Joaquin and Delta-Mendota GSAs.
The Delta-Mendota group worked with EKI Environment and Water on the new plan, which includes monitoring, overdraft mitigations, measures to avoid subsidence that damages canals and efforts to maintain water quality.
To manage the groundwater in a sustainable manner, the Delta-Mendota plan sets a 2030 goal of reducing pumping from a deep aquifer by 9,000 acre-feet annually. That will require a 20% reduction each year starting in January and continuing for five years.
According to the plan, Patterson’s wells would be pumping 460 acre-feet less in 2030, while Patterson Irrigation District usage would be 417 acre-feet less and West Stanislaus Irrigation District would use 1,680 acre-feet less. An acre-foot is equal to 325,851 gallons of water.
Pumping cutbacks also would be triggered if ground subsidence averages 2.5 inches per year within a half mile of the canals. New wells within the zone would not be permitted until the problem is corrected.
Monitoring of groundwater levels will determine if overdraft mitigations are effective. The consultant told supervisors Tuesday that the impacts of groundwater management could be fallowing land, conversion to drought-resilient crops, less economic viability and conversion of ag land to development.
The plan would exempt wells that produce no more than two acre-feet of water per year and those constructed before Nov. 25, 2014, that pump less than 10 acre-feet annually.
County supervisors referred to the plan as the best strategy for holding onto local groundwater resources.
“It is a difficult spot to find ourselves in,” Supervisor Terry Withrow said. “We know the state is serious about this. ... We are talking about fallowing land to get through this.”
Anthea Hansen, general manager of Del Puerto Water District, said only a small amount of subsidence has been measured in the area. She said the district supports the plan, as it allows for quick response if hot spots develop and protects everyone’s ability to access groundwater.
Cuts to water allocations lead to pumping
In contrast to historic water rights held by irrigation districts in eastern Stanislaus County, water districts in the Patterson area often have their contracted water allocations cut, especially in dry years. That results in groundwater pumping to irrigate orchards and row crops.
Elsewhere in the San Joaquin Valley, the Kings County Farm Bureau filed a lawsuit in May after the State Water Resources Control Board placed restrictions on agricultural well pumping in the Tulare Lake groundwater basin.
The state’s probationary status imposed in April required growers to register their wells and pay a charge of $20 per acre-foot for water pumped from the ground.
Stanislaus County officials are hoping the Delta-Mendota subbasin can avoid probation through adoption of the pumping reduction plan.
“If the state comes in and takes over, that is not going to end well,” Withrow said.
This story was originally published October 29, 2024 at 5:20 PM.
