First Steps in Inter-Basin Coordination for SGMA: Basin Boundary Modification Requests in Santa Cruz County

Cameron Tana, Sean Culkin, and Nick Byler presented this poster at the Groundwater Resources Association of California Annual Conference in Concord this week. Download this poster here. DWR has draft approved these basin boundary modifications.

First Steps in Inter-Basin Coordination for SGMA: Basin Boundary Modification Requests in Santa Cruz County
Cameron Tana, Sean Culkin, Nick Byler, and Derrik Williams, HydroMetrics Water Resources Inc.

The Sustainable Groundwater Management Act (SGMA) uses Department Water Resources (DWR) Bulletin 118 (2003) to define the groundwater basins to be managed. SGMA also provides local agencies the opportunity to request basin boundary modifications. DWR issued regulations for modification requests and accepted modification requests from January-March 2016.

Three eligible agencies in Santa Cruz County submitted basin boundary modification requests to DWR during this period. The requests varied in the types of modifications requested but shared the goal of defining each basin as the groundwater resource providing supply for each agency. In conjunction with re-prioritization of some of the basins involved , the modifications will allow each agency to focus its management efforts on its groundwater supply resource and therefore improve management of groundwater resources in the region.

1) Scotts Valley Water District (SVWD) requested expansion of its basin defined by Bulletin 118 based on surficial alluvium with a new name of the Santa Margarita Basin to represent the series of underlying stacked aquifers that provide the groundwater resource for the area.
2) The Santa Cruz Mid-County Groundwater Agency (MGA) requested consolidation of all or parts of four basins defined by Bulletin 118 based on separate areas of surficial alluvium as the Santa Cruz Mid-County Basin to represent the series of stacked aquifers that represent the shared groundwater resource for MGA.
3) Pajaro Valley Water Management Agency (PVWMA) requested jurisdictional modifications to internal boundaries of the Pajaro Valley Basin (3-2) to be consistent with PVWMA being named the exclusive Groundwater Sustainability Agency (GSA) for its jurisdiction.

These modifications involved shared boundaries between the proposed basins. SVWD and MGA had to coordinate on the scientific justification for their shared boundary while accounting for their jurisdictional areas. In addition, the two agencies had to respond to a private water company objection to the initial shared boundary. MGA had to understand PVWMA’s plans to be the exclusive GSA for its jurisdiction in proposing their shared boundary. The basin boundary modifications have the advantage of removing the need for intra-basin coordination agreements between the agencies, but inter-basin coordination will still be necessary for these connected basins. Working through the issues for modifications of the shared basin boundaries in these requests were good first steps for future inter-basin coordination to achieve groundwater sustainability in Santa Cruz County.

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