a. As part of the GSP Determination response, the Groundwater Commission formed an ad hoc committee to review the undesirable results definition and minimum thresholds. The ad hoc committee, comprised of Commission members Andrew Grady, Michael Ward, Todd Hamer, Hal Crain, and Bart Fleharty, held several meetings and developed a revised undesirable results definition and revised minimum thresholds for consideration.
The linked web map contains layers that include proposed 'Zones of Special Concern', potential recharge project locations, monitoring well locations and hydrographs, and RMS wells showing the current and proposed minimum thresholds.
b. In response to the GSP determination letters, the Undesirable Results definition will be revised. A proposed definition has been presented to the SMC Ad Hoc and Board of Directors for review.
Proposed Undesirable Results definition (as presented to the SMC Ad Hoc Committee)
Undesirable results occur when significant and unreasonable effects for any of the five sustainability indicators defined by SGMA are caused by Groundwater Conditions occurring in the Subbasin. The GSA defines the negative effects to beneficial uses and users that would be experienced as undesirable results conditions as 10 wells becoming dry (after the GSP revision) within each Thiessen polygon.
The GSA will address the adverse impacts, if any, through projects to supplement supplies of water and through a well mitigation program. The impacts to groundwater dependent ecosystems that may occur without rising to significant and unreasonable levels constituting undesirable results has yet to be determined.
The GSA is actively addressing data gaps and monitoring to establish the relationship between interconnected surface water and groundwater and the potential adverse effects of depletion of groundwater. The GSA will update the Undesirable Results definition to include a depletion of interconnected surface water in the 5 year update in January 2027.
c. In response to the GSP determination response, the Minimum Thresholds were revised and Special Zones were created. The Minimum Thresholds and Special Zones will be presented to the Board of Directors in April.
The proposed Minimum Threshold methodology is noted below; levels for individual RMS wells can be viewed on the linked web map.
Proposed Minimum Threshold methodology (as presented to the SMC Ad Hoc Committee)
• Minimum Thresholds within Specialized Zones: 2015 - 2022 Groundwater Low
Specialized Zones are based on Reported Dry Wells)
• Minimum Thresholds Outside of Specialized Zones: 2015 - 2022 Groundwater Low plus a 20’ buffer