San Luis Obispo County Water Resources

Public Works Department


Santa Maria River Valley Groundwater Basin Non-Adjudicated "Fringe Areas"


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The Santa Maria River Valley Groundwater Basin (Santa Maria Basin), DWR Bulletin 118 Basin No. 3-12 , underlies the coastal portion of the northern Santa Barbara and southern San Luis Obispo Counties. The DWR-defined Santa Maria Basin encompasses approximately 184,000 acres (288 square miles), of which approximately 61,220 acres (95.7 square miles) are within San Luis Obispo County. There are five "fringe areas" within the San Luis Obispo portion of the basin that are not subject to the adjudication stipulated in 2005. These fringe areas include the Pismo Creek Valley (approx. 1,220 acres), Arroyo Grande Valley (3,860 acres), Nipomo Valley (6,230 acres), Southern Bluffs (4,030 acres), and Cuyama River Plains (1,560 acres). Annual precipitation for the basin ranges from 13 to 17 inches with an average of 15 inches. Groundwater is found in alluvium, dune sands, and the Orcutt, Paso Robles, Pismo, and Careaga Formations of the basin. Groundwater is unconfined throughout most of the basin except in the coastal portion where it is confined.


In 2015, the State legislature approved an important new groundwater management law known as the Sustainable Groundwater Management Act (SGMA). SGMA requires that high and medium priority basins comply with the new law, with certain exceptions for certain adjudicated basins – DWR designated Santa Maria Basin as a high priority basin. SGMA does not apply to the portion of the Santa Maria basin that is at issue in the litigation (“adjudicated area”) provided that certain requirements are met. The adjudicated areas cover a majority of the basin, and are managed by the Northern Cities Management Area, Nipomo Mesa Management Area, and the Santa Maria Valley Management Area. However, the fringe areas described above must comply with the new groundwater management requirements. The maps below show both the adjudicated areas exempt from SGMA, and the fringe areas that are subject to SGMA.



Interactive Map of Santa Maria River Valley Groundwater Basin Fringe Areas

Welcome to the SGMA Interactive Data Viewer for the Santa Maria Basin! This is an interactive mapping system to help you to navigate around the Santa Maria groundwater basin by panning, zooming, or searching for a specific parcel or street address that you would like to locate. There are different map layers that can be shown and superimposed in this interactive mapping system such as boundaries of groundwater basins, cities, roads, SGMA eligible entities, and others by checking the layer names indicated on the left panel layer menu. To search and locate a specific APN or street address on the map


1. Enter either the nine-digit parcel number (APN) including hyphens or the complete street address in the “Search...” bar on the upper right hand corner of the map screen and then click on the search button to locate it. The APN or street address that you just entered will appear on the left panel and a location marker will show up on the map to identify the location.

2. Click on the APN or street address name shown on the left panel layer menu will zoom in to the specified location for a close-up look


Click here to open the Interactive Map of Santa Maria Groundwater Basin in a new window




Current News, Information, and Upcoming Meetings

Upcoming Announcements:


County Board of Supervisors Meeting

Request to approve and authorize a Notification on Intent to initiate development of a groundwater sustainability plan for the “fringe areas” of the Santa Maria River Valley Groundwater Basin within the County of San Luis Obispo.


    Tuesday, January 29, 2019, 9:00 AM

    San Luis Obispo Board of Supervisors Chambers

    1055 Monterey Street

    San Luis Obispo, Ca 93408


    Agenda Item #25


Draft Basin Boundary Modifications Released

The California Department of Water Resources (DWR) has released Draft Basin Boundary Modifications. To view Draft Basin Boundary Modifications results, please click here


For additional information, please visit DWR’s Basin Boundary Modification website by clicking here.



On June 5, 2018, the County Board of Supervisors adopted a resolution to formally initiate and submit the proposed Santa Maria Basin BBMR to the California Department of Water Resources (DWR). Subsequently, a BBMR application was submitted to DWR by the Santa Maria Basin Fringe Areas – County of San Luis Obispo Groundwater Sustainability Agency (County) and is now considered complete after DWR’s initial review and posted on DWR’s SGMA portal. The public comment period will close on October 7, 2018. Please click here to view information regarding the State/County public commenting process for the BBMR and how comments can be submitted. The BBMR map can be found here.


Notice for comments

Comment Period: Sep 7 - Oct 7, 2018.


Past Workshops and Public Meetings:


County Board of Supervisors Hearing

    Tuesday June 5, 2018

    9:oo AM

    San Luis Obispo Board of Supervisors Chambers

    1055 Monterey Street

    San Luis Obispo, Ca 93408



Santa Maria Groundwater Basin Boundary Modifications – Public Meeting

    Thrusday, April 12, 2018

    6:00 p.m. - 8:00 p.m.

    Georgie O'Connor Board Room 602 Orchard Street, Arroyo Grande, CA 93420



Approval to explore basin boundary modification for the Santa Maria River Valley Groundwater Basin

    Tuesday, March 6, 2018

    9:00 AM

    San Luis Obispo Board of Supervisors Chambers

    1055 Monterey Street

    San Luis Obispo, CA 93408


Presentation on the Results of the Santa Maria Valley Basin Characterization Study

    February 27 & 28, 2018

    Nipomo High School (Forum Building) & South County Regional Center

    *This information was presented at two optional meetings in February. Both meetings presented the same content. Please click the Presentation link above to download the presentation.


Santa Maria Fringe Area - 2nd SGMA|Stakeholder Forum


SGMA 101

    Wednesday, September 14, 2016

    6:00 PM - 8:30 PM

    South County Regional Center

    800 W Branch St.

    Arroyo Grande, CA 93420



More Information

For more information on the Sustainable Groundwater Management Act, please visit here.




Santa Maria River Valley Basin Documents and Reports

Santa Maria Groundwater Basin Characterization and Planning Activities Study Final Report


Santa Maria River Valley Groundwater Basin Basin Boundary Modification Request Technical Report


Santa Maria River Valley Groundwater Basin Fringe Area Characterization Study


Water Resources of The Arroyo Grande - Nipomo Mesa Area



How to Get Involved?

  • Check back to see current news, information, and upcoming meetings.
  • Show up at upcoming meetings.
  • Sign up for the SGMA Mailing List here.
  • Contact Information:
    • County - Dick Tzou

      (805) 781-4473


SGMA Mailing List

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