Los Osos Valley Groundwater Basin

The Los Osos Valley Groundwater Basin, DWR Bulletin 118 Basin No. 3-08, is bounded on the north by Park Ridge, on the south by Irish Hills, on the west by Morro Bay, and on the east by a drainage divide separating Los Osos Valley from San Luis Valley. The Los Osos Basin, as defined by DWR, is located in San Luis Obispo County and covers 6,990 acres (10.9 square miles).

On February 11, 2019, DWR released the 2018 Final Basin Boundary Modifications for Los Osos Valley Groundwater Basin, including the following basin modifications: 

  • DWR approved the creation of two jurisdictional subbasins:
    • Los Osos Area Subbasin (3-08.01)
    • Warden Creek Subbasin (3-08.02)
  • DWR approved the removal of the southern fringe area
  • DWR denied the removal of the minor northern fringe area

#mc_embed_signup{clear:left; font:14px Helvetica,Arial,sans-serif; } /* Add your own MailChimp form style overrides in your site stylesheet or in this style block. We recommend moving this block and the preceding CSS link to the HEAD of your HTML file. */

Sustainable Groundwater Management Act

In 2015, the State legislature approved a groundwater management law known as the Sustainable Groundwater Management Act (SGMA). DWR categorized the Los Osos Valley Groundwater Basin as a high priority basin and designated the basin to be in a “condition of critical overdraft”. SGMA does not apply to the portion of the Los Osos Valley – Los Osos Area Subbasin at issue in the litigation (“adjudicated area”) provided that certain requirements are met by the Los Osos Basin Management Committee.

The Warden Creek Subbasin and minor northern fringe area are located in the non-adjudicated areas of the basin, the County of San Luis Obispo formed a groundwater sustainability agency in to manage these basin areas within their respective jurisdictions (see “Final Basin Boundary Modifications Release” in Recent News Section below for more details).  The map below displays both the adjudicated area exempt from SGMA, and the newly modified basin fringe areas that are subject to SGMA, pending the State’s prioritization basin results anticipated in Spring 2019. 

Recent News & Announcements

Final Basin Boundary Modifications Released

DWR has released the 2018 Final Basin Boundary Modifications decisions and accompanying documents.

Click on the following links to view the 2018 Final Basin Boundary Modifications results:

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

Prioritization for Modified Basins Released

On April 30, 2019, DWR announced Basin Prioritization Phase 2 draft results for basins with modified boundaries. This announcement begins a 30-day public comment period to allow input from the public and local agencies.

Public comments submitted to DWR can be viewed by clicking here.

On December 18, 2019, DWR announced completion of the Phase 2 Basin Prioritization, designating the Los Osos and Warden Creek Subbasins as very low priority.

Meeting Information

The County provides updates on SGMA at the Los Osos Groundwater Basin Management Committee (BMC) meetings regularly held on the 3rd Wednesday of every month starting at 1:30pm at the South Bay Community Center on 2180 Palisades Avenue in Los Osos, CA. Click here to view the Los Osos BMC Meeting Calendar.

How do I get involved?

Interactive Map of the Los Osos Groundwater Basin

Click the link above to access the SGMA Interactive Data Viewer for the Los Osos Valley Groundwater Basin! This is an interactive mapping system to help you to navigate around the Los Osos Valley 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

Sign up for the SGMA Mailing List

Click here to subscribe to the SGMA email notification list!

Related Forms & Documents