Office of the Delta Watermaster

Term 91

Term 91 has been included in all permits and licenses, granted after 1965, for diversion and use of water in the Delta watershed. Term 91 requires that those holding such permits and licenses cease diverting water when the State Water Resources Control Board’s Division of Water Rights (Division) gives notice that Term 91 is in effect. The Division will also give notice when Term 91 is no longer in effect.

Term 91 is designed to interrupt diversions under junior water rights when conditions in the Delta watershed threaten certain water quality objectives. When such conditions occur (generally in the hot and dry months of most years), the State Water Project and the Central Valley Project are required to release previously stored water from their upstream reservoirs in order to meet those water quality objectives.

The complex calculations to determine when conditions may trigger Term 91 are illustrated in the graph available at the following link: 2019 Term 91 Curtailment Graph

Standard Term 91 (Stored Water Bypass Requirements)

When natural flows to the Delta are insufficient to meet water quality standards, the State Water Project and the Central Valley Project (Projects) will be operated to meet instream water quality standards. The Projects will release supplemental, stored water to meet the water quality standards which may trigger Term 91.

More information on the DWR/USBR CVP-SWP table for Term 91 calculations.

Prior Water Year Term 91 Curtailment Graphs (2018, 2017, 2016, 2015)

New! Term 91 Water Availability and Curtailment Frequently Asked Questions (FAQ), November 30, 2018


Term 91 Curtailment Notices

Year Advance Notice Curtailment Notice Final Notice Extension Notice
2018 05/18/18 06/01/18 11/30/18
2017 No Curtailment
2016 05/10/16 06/02/16 10/14/16
2015 02/13/15 10/02/15 12/15/15
2014 02/03/14 11/26/14
02/11/14 01/08/14
2013 04/17/13 10/24/13 11/15/13
05/01/13 05/30/13 08/27/13
2012 05/10/12 07/24/12

Questions about these Notices?