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December 11 GSC Meeting Summary

GSC Previews Data and Tools that Will Support Future SLO Basin Management

At its quarterly meeting on December 11, GSA staff provided an update on the GSP development status to the GSC and nearly two dozen stakeholders, including an overview of key data and analysis that will inform how groundwater will be managed in the Basin moving forward.

Official review and comment was accepted for the draft of Chapter 3: Description of the Plan Area and Chapter 4: Basin Setting. Public comment on these chapters ended January 31. Chapter 3 provides a description of the SLO Basin plan area including its jurisdictional boundaries, the location and density of wells, future land use plans, and existing groundwater monitoring and management programs. Chapter 4 describes the Basin topography and boundaries, the primary users of groundwater in the Basin, regional geology, principal aquifers, surface water bodies, and an analysis of the Basin’s subsidence potential.

Next, the project team provided attendees a preview of key data that will be published in Chapter 5: Groundwater Conditions, scheduled for release at the March 11, 2020 GSC meeting, and Chapter 6: Water Budget, which will be released at the June 10, 2020 GSC meeting.

Using a series of topographical maps, the project team demonstrated the historical changes in groundwater levels throughout the SLO Basin, namely in areas of concern such as Edna Valley from Spring 1997 to Spring 2011, a time period demarked by widespread vineyard planting just before the most recent drought. Within that period, groundwater declined more than 40 feet near the Tiffany Ranch Road area on the southern tip of the Edna Valley Basin near Arroyo Grande.

The team also previewed results of their geophysical survey and the water budget, now in development. The geophysical survey defined the depth and thickness of various subsurface layers to characterize their water supply capacity, especially near the divide of the San Luis and Edna Valley areas. Further, the project team reported that progress is still being made on the development of the Integrated Groundwater/Surface Water Model.

The team also announced its next public workshop on April 8, where participants can work with the project team to define the sustainability goals for the Basin. This is first interactive workshop in the planning process.


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