1. DWR identified two subsidence deficiencies in the Merced Subbasin groundwater plan. The California Department of Water Resources issued an incomplete determination letter dated October 8, 2026. Staff described two deficiencies: the plan does not adequately define how much total subsidence is allowable, and it needs more support for its groundwater-level stabilization measures and their relationship to subsidence. The subbasin’s three groundwater sustainability agencies have 180 days, with a resubmission deadline of April 6, 2027, to address the deficiencies. Staff said technical work has been underway since a May meeting with DWR and described the response period as sufficient.
2. Satellite data show subsidence in affected areas, including localized readings approaching four feet. Data covering June 2015 through June 2025 showed roughly 1–2.5 feet of land-surface decline in affected parts of the Merced Subbasin. DWR’s letter also identified localized areas with nearly four feet of subsidence. Staff said the cause of one localized area was not yet clear. Staff pointed to affected areas along the subbasin boundary and to subsidence outside it. They said limited historical groundwater-level data make it difficult to determine critical head—the groundwater level below which clay compaction and subsidence occur—and to assess which management actions within the subbasin could practically address the problem.
Already have an account? Sign In
