Butte County staff say 2024 water year brought improved groundwater levels and storage

Butte County staff presented the county'level groundwater status report for water year 2024 to the Butte County Water Commission on April 2, saying hydrologic conditions were generally favorable and that groundwater levels and storage improved from the prior year.

Kelly, presenting the county report required under county code chapter 33, said the county compiled the report from the three subbasin annual reports and consultant work and that the county has produced these status reports for two decades. "This report is required under county code, chapter 33," Kelly said during the presentation.

Kelly described 2024 as an "above normal" water year on the Sacramento Valley Water Year Index and noted regional runoff and Lake Oroville levels that supported surface supplies. Countywide precipitation and surface flows were near average in many areas, and those surface supplies helped reduce pumping demands in places that are less groundwater dependent.

Breaking the county-wide picture into the three subbasins, Kelly said: - Butte Subbasin: groundwater levels rose about one foot year'over'year and the subbasin relies heavily on surface water (roughly 83% of total 2024 use), with only about 17% from groundwater. Pumping increased slightly but cumulative storage also rose. - Vina Subbasin: representative monitoring wells rose about two feet on a one'year comparison; Vina remains highly groundwater dependent (roughly 90%+ of use is groundwater) and long'term trends still reflect declines in many wells despite recent gains. - Wyandotte Creek Subbasin: largely stable seasonal changes in 2024 were reported, but the subbasin has fewer monitoring wells (9'12) and staff recommended expanding the monitoring network.

Kelly identified county priorities for 2025 including tracking wells with long'term declines and dry'well reports, administering the Drought Resilience and Outreach Program (DROP) for well repair and replacement, monitoring water quality in Wyandotte Creek where the Ione formation can cause high electrical conductivity, and pursuing recharge and irrigation'efficiency projects. She also noted the Environmental Health Division has funding to begin a revision to the county well ordinance and that the revision will include stakeholder outreach and public hearings.

Commissioners pressed staff on methodology for estimating pumping and the interpretation of cumulative storage decline lines in graphics; Kelly said some recent changes in estimation methodology explain part of the difference and pointed to representative monitoring wells as the basis for storage calculations. Members of the public urged staff to include upper'watershed precipitation stations and to monitor fractured'rock aquifers that lie outside SGMA subbasins.

The commission voted by voice to accept Kelly's presentation as an informational item.