Annual reports show 2025 storage gains but long‑term groundwater deficit persists

Tehama GSA staff presented annual reports for Bowman, Red Bluff, Antelope, Los Molinos and Corning subbasins, reporting that the 2025 water year was classified as "above normal" and produced year‑to‑year positive change in groundwater storage, though long‑term cumulative storage remains in deficit compared with the 1990 baseline.

Will Anderson, standing in for the regular presenter, walked commissioners through extraction and change‑in‑storage charts, hydrograph appendices and a spatial breakdown of storage changes. For the Bowman subbasin he said "2025 was classified as an above normal year," with storage changes modestly positive but cumulative deficits remaining over multi‑decadal baselines.

Staff reported no indication of undesirable results for most sustainability indicators across the subbasins in 2025, though Corning had nine RMS wells below their minimum threshold during fall measurements. Antelope had two nitrate measurements that exceeded the monitoring objective (MO) but not the minimum threshold.

Several commissioners flagged apparent inconsistencies in the municipal and rural residential groundwater use tables (sharp increases compared with the 2023 report) and asked staff to double‑check the source datasets and calculations. Commissioners also requested more explicit reporting of rate‑of‑decline measures and longer‑period change‑in‑storage maps to better evaluate localized trends and identified small areas of inelastic subsidence for future agenda consideration.

Staff said hydrographs and appendices are included with the annual reports and committed to reviewing the flagged table anomalies and reporting back at the next meeting.