When water users within a basin are in dispute over legal rights to the water, a court can issue a ruling known as an adjudication. Adjudications can cover an entire basin, a portion of a basin, or a group of basins and all non-basin locations between. The court decree will define the area of adjudication.
In basins or portions where a lawsuit is brought to adjudicate, the groundwater rights of all the overliers and appropriators are determined by the court.
The court also decides:
- Who the extractors (owners) are
- How much groundwater those well owners can extract
- Who the Watermaster will be to ensure that the basin or portion of the basin is managed in accordance with the court's decree
Prior to the passage of the SGMA, 22 basins - mostly in Southern California - had adjudicated areas. SGMA established a process for adjudicated basin Watermasters or local agencies to report information according to .
On October 9, 2015, California Governor Jerry Brown signed AB 1390 and SB 226 to implement a comprehensive approach to groundwater basin adjudications throughout the state. DWR is required to post notice and form answers received by plaintiffs related to comprehension adjudication activities (Code of Civil Procedure 836(m)). DWR has received the following notice and form answers:
Los Posas Basin v. Fox Canyon Adjudication (Received: 11/13/2018)
- By April 1, 2016, submit to DWR a copy of a governing final judgment, or other judicial order or decree, and any amendments entered before April 1, 2016.
- Within 90 days of entry by a court, submit to DWR a copy of any amendment made and entered by the court to the governing final judgment or other judicial order or decree on or after April 1, 2016.
- By April 1, 2016, and annually thereafter, submit to DWR a report containing the following information to the extent available for the portion of the basin subject to the adjudication:
- Groundwater elevation data unless otherwise submitted pursuant to Section 10932.
- Annual aggregated data identifying groundwater extraction for the preceding water year.
- Surface water supply used for or available for use for groundwater recharge or in-lieu use.
- Total water use.
- Change in groundwater storage.
- The annual report submitted to the court.