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 (GSA) to manage these basin areas within their respective jurisdictions.

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