Eastern Municipal Water District

Action/Info Item

Approve and Authorize West San Jacinto and Southwest San Timoteo Groundwater Basins Boundary Modifications


Department:Groundwater Management & Facilities PlanningSponsors:
Category:Action/Info ItemMeeting Workflows:Board Planning Committee Workflow


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The Sustainable Groundwater Management Act (SGMA) was signed into law on September 16, 2014.  The intent of SGMA is to promote sustainable management of groundwater basins.  SGMA requires that medium and high priority basins be managed by a Groundwater Sustainability Agency (GSA), and grants new and additional groundwater management authorities to GSAs.  On December 7, 2016, EMWD’s Board approved Resolution 2016-135 to become the GSA for the West San Jacinto Groundwater Basin. On June 7, 2017, EMWD’s Board approved Resolution 2017-050 to become the GSA for the Southwest San Timoteo Groundwater Sub-basin.


Groundwater basin boundaries throughout California are established based on the limits of alluvial aquifers, and are described in a publication produced by the Department of Water Resources (DWR) called “Bulletin 118 California’s Groundwater” (Bulletin 118).  With the passage of SGMA, the basin boundaries described in Bulletin 118 have taken on greater significance.  The San Jacinto Groundwater Basin, as defined in Bulletin 118 (Basin No. 8-005), has been identified by DWR as a “high priority” basin, making it subject to more aggressive deadlines in the SGMA regulations.  The San Timoteo Groundwater Sub-basin, as defined in Bulletin 118 (Basin No. 8-002.08), has recently been reassigned by DWR as a “very low priority” basin and management action is voluntary based on the SGMA regulations.


SGMA established a process for local agencies to revise the boundaries of an existing Bulletin 118 basin to better represent the local groundwater aquifer and enhance management of the basin.  EMWD submitted Bulletin 118 basin boundary modification requests to DWR for both the San Jacinto Groundwater Basin and the San Timoteo Groundwater Sub-basin before the June 30, 2019, deadline.  The basin boundary modification requests were based on scientific justification that most accurately defined the sedimentary basin relative to the well-consolidated bedrock within and surrounding the exiting basin boundaries.


DWR finalized the approved basin boundary results on February 11, 2019.  The San Timoteo Groundwater Sub-basin boundary modification request was fully approved by DWR.  As such, the area encompassing the Southwest San Timoteo GSA has been removed from the sub-basin boundary.  The Board is being requested to consider withdrawal of EMWD as the Southwest San Timoteo GSA because this sub-basin is no longer within EMWD’s sphere of influence.  The San Jacinto Groundwater Basin boundary modification request was approved in all areas except the area encompassing Lake Perris.  As a result of the basin boundary modification approval, the West San Jacinto GSA will be revised to reflect the modifications approved by DWR.  The Board is also being requested to consider approval of the revised West San Jacinto GSA area, which excludes adjudicated areas of the basin and March Air Reserve Base.

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Water Supply Diversity and Reliability: Develop and implement a portfolio of projects and management techniques to achieve a reliable and cost-effective balance of water supplies utilizing imported, local and recycled water sources.





Approve and Amend Resolution 2016-135 to revise the West San Jacinto Groundwater Sustainability Agency Area to be consistent with the basin boundary modification as approved by DWR; and Rescind Resolution 2017-050 and withdraw EMWD as the Southwest San Timoteo Groundwater Sustainability Agency for the San Timoteo Sub-basin.

Meeting History

Apr 11, 2019 3:30 PM  Board Planning Committee Regular Meeting
draft Draft
Apr 17, 2019 9:00 AM  Board of Directors Regular Meeting
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Ms. Gray provided an update on this item

MOVER:Stephen J. Corona, Board Member
SECONDER:Philip E. Paule, Vice President
YES:Ronald W. Sullivan, Philip E. Paule, Stephen J. Corona
ABSENT:Randy A. Record, David J. Slawson