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Water Measurement and Reporting Regulation (aka SB 88)

Senate Bill 88 requires that all water right holders who have previously diverted or intend to divert more than 10 acre-feet per year or are authorized to divert more than 10 acre-feet per year under a permit, license, or registration, are required to measure and report the water they divert.

Diverters must measure their diversions monthly, weekly, daily, or hourly, depending on the type and size of diversion. In general, diverters only need to submit their measurement data to the State Water Board once per year. Data is submitted as an attachment to Annual Water Diversion and Use Reports. Optional datafile templates are available. Refer to the Measurement and Reporting Manual for more information on measurement frequency requirements.

Measuring devices can be any devices, including custom or in-house built devices, that directly measure either volume, flow rate, water velocity, or water elevation. Diverters must then use the measured value to calculate the volume of water diverted. Examples of measuring devices are shown in the table below.

Example Devices

Measured Parameter

Example Units

Formulas to Calculate Volume

Totalizer; totalizing flow meter


Acre-feet; gallons; cubic feet

Not applicable

Flow meter

Flow rate

Gallons per minute; cubic feet per second

Volume = flow rate x duration

Velocity meter

Water velocity

Feet per second

Volume = velocity x cross sectional area x duration

Staff gauge; transducer; weir

Water elevation


Diverter must provide formula

Additional information regarding frequency of measurement, and how to report can be found on the State Water Resources Control Board website.



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