San Luis Obispo County Key Well Index Analysis

The San Luis Obispo County Flood Control and Water Conservation District manages a countywide groundwater monitoring program that measures the water levels in more than 300 wells. The data from this monitoring program has helped the County assess groundwater resources in its five medium- and high-priority basins. To use the data publicly, the County needed a way to report aggregated data so as not to compromise the confidentiality of individual well owners.

GSI conducted a key well index analysis that enabled County personnel to quickly see the condition of the San Luis Obispo Valley Basin and share data from its groundwater monitoring program with the public without compromising well owner privacy. GSI selected key representative wells within each basin and aggregated these into groups of wells, and then developed hydrographs and maps to show average water elevation of well groups and change in elevation within each basin.

GSI's work involved:

• Judiciously selecting key representative wells within each basin.
• Aggregating key wells into groups of wells, helping to refine data gaps in the existing monitoring program and present trend analyses and hydrographs compliant with the Sustainable Groundwater Management Act (SGMA).
• Developing hydrographs and maps to show average water elevation of well groups and change in elevation within each basin while maintaining well owner privacy.
• Analyzing data gaps and evaluating whether an increased density of key wells would be needed.