California Water Diversion Measurement and Recordkeeping

In general, those who divert more than 10 acre-feet per year are required to measure their diversions and submit the data to the State Water Board. This includes diverters who have - A single water right with a face value or historical use (whichever is greater) of more than 10 acre-feet per year - Multiple water rights that share either a point of diversion, place of use, or divert to the same reservoir and have a combined face value or historical use of more than 10 acre-feet per year - A storage facility with a capacity of more than 10 acre-feet Note: The 10-acre-foot threshold is based on the greater value of historical use or face value. It is not based on the amount of water diverted or stored during the current water year.

| Direct Diversion: Requirements are based on the face value or maximum annual historical use (whichever is greater) For multiple water rights that share a point of diversion or place of use, requirements are based on the combined face value or maximum annual historical use (whichever is greater) of all such water rights | More than 10,000 acre-feet | Hourly, plus telemetry requirements

Starting October 1, 2026, Large Diversion Requirements will replace the Telemetry Requirements of the previous version of the regulation. In addition to measuring the general measurement parameters described in the “What to Measure” section, diverters with any of the following are also subject to Large Diversion Requirements: - A claimed water right with a maximum allowable diversion amount greater than 10,000 acre-feet per year - A claimed water right with a maximum allowable direct diversion rate greater than 30 cubic feet per second - A combination of rights that share a point of diversion and have a combined maximum allowable diversion amount greater than 10,000 acre-feet per year - A combination of rights that share a point of diversion and have a combined maximum allowable direct diversion rate greater than 30 cubic feet per second Note: Diverters that were not previously subject to telemetry requirements have until October 1, 2027 to begin meeting the large diversion requirements.

Any other procedure used to convert the raw device output into a general measurement datafile or large diversion submission. Diverters must register measuring devices and submit a measurement methodology through CalWATRS by January 31, 2027.

Diverters do not need to submit the raw output from their measuring devices in addition to their general measurement data file, but they must maintain records of the raw device output for at least 10 years.