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Document ID us-ca-wamere-2026-03-23 Title Water Measurement Regulation URL https://www.waterboards.ca.gov/waterrights/water_issues/programs/diversion_use/water_measurement.html Jurisdiction /us/ca Subdomain(s) none Language Status completed Analyzed at 2026-05-12 05:02:58.780619+00:00 Relevance inventory_targeted_fetch

Q Qualitative Requirements (30)

Req ID Category Intent Legal Status Name Subdomain(s) Context Conditions Confidence
#Q001monitoringoperationalmandatoryGeneral Diversion Measurement Requirement (WY 2026)otherIn 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.Applies to those who divert more than 10 acre-feet per year.high
#Q002monitoringreportingmandatoryMeasurement and Reporting by Water RightotherDiverters must measure and report their diversion volumes by water right.high
#Q003monitoringoperationalmandatoryRequired Measurement Volumes (WY 2026)otherDiverters must measure each of the following, as applicable: * Volume of water directly diverted under each water right * Volume of water diverted to storage under each water right * Volume of water withdrawn and/or released from storage under each water rightAs applicable.high
#Q004monitoringoperationalmandatoryReservoir Drawdown and Refill MeasurementotherFor reservoirs that operate in a pattern of drawdown and refill, diverters must also record each of the following: * Maximum and minimum water surface elevation during each drawdown-refill cycle * Reservoir volumes corresponding to these elevations * Dates of these measurementsFor reservoirs that operate in a pattern of drawdown and refill.high
#Q005monitoringoperationalmandatoryDiversion Measurement MethodsotherDiverters must measure their diversions using a measuring device, measurement method, or combination of devices and/or methods.high
#Q006reportingreportingmandatoryVolume Calculation from Measuring DevicesotherDiverters must then use the measured value to calculate the volume of water diverted.When using measuring devices that directly measure volume, flow rate, water velocity, or water elevation.high
#Q007administrativereportingmandatoryMeasuring Device Registration (January 2027)otherOn or before January 31, 2027, diverters must register each of their measuring devices in CalWATRS.high
#Q008administrativereportingmandatoryPrior Submission of Measurement MethodotherDiverters must have previously submitted a measurement method to the Board before February 1, 2026.When using measurement methods rather than measuring devices.high
#Q009monitoringreportingmandatoryAlternative Compliance Plan ImplementationotherDiverters who measure and submit data under an ACP must meet their specified measurement requirements as much as possible and explain why they are unable to fully meet all requirements.When operating under an Alternative Compliance Plan (ACP).high
#Q010administrativereportingmandatoryAlternative Compliance Plan Registration (January 2027)otherAll diverters pursuing alternative compliance must submit an ACP through CalWATRS on or before January 31, 2027 (regardless of whether they submitted a prior ACP before February 2026).Applies to all diverters pursuing alternative compliance.high
#Q011monitoringoperationalmandatoryMeasurement Frequency GuidelinesotherDiverters must measure their diversions monthly, weekly, daily, or hourly, depending on the type and size of diversion.high
#Q012reportingreportingrecommendedData File Submission (WY 2026)otherDiverters should compile measurement data in a data file and submit it as an attachment to their Annual Water Diversion and Use Reports.high
#Q013administrativereportingmandatoryMeasurement Methodology RegistrationotherEach diverter must register their measuring devices in CalWATRS and submit a measurement methodology that describes how they collect, interpret, and process the raw data from their measuring devices to meet the measurement requirements.high
#Q014operationaloperationalmandatoryQualified Individual RequirementotherMeasuring diversions can be complex, therefore a qualified individual must ensure that your diversions are measured accurately.high
#Q015monitoringoperationalmandatoryWho Needs to Measure Diversions (WY 2027 and Beyond)otherAny diverter with any of the following must measure their diversions and submit the data to the State Water Board: A claimed water right that has a maximum allowable diversion amount greater than 10 acre-feet per year, or A combination of claimed water rights that either share a point of diversion or divert to the same reservoir, if the sum of the maximum allowable diversion amounts of the claimed water rights is greater than 10 acre-feet per year.Applicable starting Water Year 2027.high
#Q016monitoringreportingmandatoryGeneral Measurement Parameters (WY 2027 and Beyond)otherDiverters must measure the following: Date and time of measurement, Volume and rate of water directly diverted, and Volume and rate of water diverted to storage.Applicable starting Water Year 2027.high
#Q017monitoringreportingmandatoryQualifying Reservoir Measurement Requirements (WY 2027 and Beyond)otherDiverters with water rights to store or withdraw water from reservoirs with a capacity greater than 5,000 acre-feet (called “qualifying reservoirs”) must also measure the following: Volume and rate of water withdrawn from storage (i.e., water removed for immediate or downstream use), and Volume and rate of water released from the reservoir (i.e., total reservoir outflow).For reservoirs with capacity > 5,000 acre-feet.high
#Q018reportingreportingmandatoryMeasurement Methodology Description (WY 2027 and Beyond)otherIn your Measurement Methodology, you must describe how you converted to volume and flow rate.When using a measuring device that does not directly measure volume and flow rate.high
#Q019administrativereportingmandatoryDevice Registration and Methodology Submission (January 2027)otherDiverters must register measuring devices and submit a measurement methodology through CalWATRS by January 31, 2027.high
#Q020reportingreportingmandatoryApportionment of Measurement Data (WY 2027 and Beyond)otherDiverters must submit their general measurement data (described in the "What to Measure" section above) in the form of a general measurement data file, with data apportioned to individual water rights.high
#Q021reportingreportingmandatoryRecord Retention for Raw Device Output (WY 2027 and Beyond)otherDiverters 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.high
#Q022monitoringreportingmandatoryLarge Diversion Parameters MeasurementotherFor any claimed water right or point of diversion that meets any of the criteria described above, diverters must measure the following: Date and time of measurement and Volume and rate of diversion (Note: you do not need to distinguish between direct diversions and diversions to storage).Applicable to large diversions starting October 1, 2026.high
#Q023monitoringreportingmandatoryLarge Diversion Reservoir ParametersotherDiverters with water rights to store or withdraw water from reservoirs with a capacity greater than 5,000 acre-feet must also measure the following: Total volume of water in the qualifying reservoir and Volume and rate of water leaving the reservoir (including all outflow and water withdrawn for use).For large diversion reservoirs with a capacity > 5,000 acre-feet.high
#Q024reportingreportingmandatorySubmitting Large Diversion Measurement Data FrequencyotherIn general, diverters need to submit their large diversion submissions on a weekly basis, with a lag time of no more than 7 days between the most recent measurement and the submission date.Applicable to large diversions.high
#Q025reportingreportingmandatoryLarge Diversion Submission Method (Beginning October 2027)otherBeginning October 1, 2027, diverters must submit their large diversion submissions in one of the following ways: Using a standardized data file template provided by the State Water Board (templates will be available in CalWATRS), Directly transmitting their large diversion submission to CalWATRS, or Posting their large diversion submission to a website approved by the Deputy Director...Beginning October 1, 2027.high
#Q026operationaloperationalmandatoryQualified Individual Accurate Measurement AssuranceotherA qualified individual must ensure that diversions are measured accurately. Qualified individuals are responsible for installing and verifying the accuracy of measuring devices and certifying that measurement methodologies and alternative compliance plans meet regulatory requirements.high
#Q027reportingreportingmandatoryAlternative Compliance Plan Deficiencies StatementotherDiverters must fulfill as many requirements of the regulation as they can, and describe in their ACP which requirements they are unable to meet and what they proposed to do instead. Diverters with ACPs must still submit measurement data.When operating under an Alternative Compliance Plan.high
#Q028administrativeoperationalmandatoryUpdated ACP Submission DeadlineotherDiverters must submit an updated ACP (based on the updated requirements), on or before January 31, 2027.For ACPs submitted before February 1, 2026.high
#Q029administrativeoperationalmandatoryNew ACP Submission DeadlineotherDiverters wishing to submit a new ACP must do so according to the updated requirements of the revised regulation. They must submit their ACP to the Board on or before January 31, 2027 or before implementing the ACP, whichever is later.For ACPs submitted on or after February 1, 2026.high
#Q030administrativeunknownguidanceThermal Plan Exception Authoritywastewater, otherRegional Boards may, in accordance with Section 316(a) of the Federal Water Pollution Control Act of 1972 and subsequent federal regulations [collectively termed the Clean Water Act] including 40 CFR 122, grant an exception to Specific Water Quality Objectives in this Plan.In accordance with Section 316(a) of the Federal Water Pollution Control Act of 1972 and subsequent federal regulations including 40 CFR 122high

P Quantitative Requirements (13)

Req ID Category Intent Legal Status Name Subdomain(s) Limit Type Limit Value Context Conditions Confidence
#P001operationalreportingmandatoryGeneral Measurement Thresholdotherrequirement> 10 acre-feet per yearrequires diverters who divert more than 10 acre-feet of water per year to measure their diversions and submit the data to the State Water BoardBased on the greater value of historical use or face value.high
#P002operationalreportingmandatoryGeneral Measurement Accuracy (WY 2026)otherrequirement<= 10 to 15 percentIn general, measurements must be accurate to within ±10 to 15 percent, depending on the size of the water right.Depending on the size of the water right.high
#P003operationalreportingmandatoryDirect Diversion Measurement Frequency (> 10,000 acre-feet)otherrequirement> 10,000 acre-feetDirect Diversion Volume Threshold: More than 10,000 acre-feetRequired Measurement Frequency: Hourly, plus telemetry requirementshigh
#P004operationalreportingmandatoryDiversion to Storage Measurement Frequency (10,000 acre-feet or more)otherrequirement>= 10,000 acre-feetDiversion to Storage Volume Threshold: 10,000 acre-feet or moreRequired Measurement Frequency: Hourly, plus telemetry requirementshigh
#P005operationalreportingmandatoryQualified Individual Threshold (Standard)otherrequirement<= 200 acre-feet per yearFor diversions of 200 acre-feet per year or less, a qualified individual can be anyone trained and experienced in water measurementhigh
#P006operationalreportingmandatoryQualifying Reservoir Capacity (WY 2027)otherrequirement> 5,000 acre-feetDiverters with water rights to store or withdraw water from reservoirs with a capacity greater than 5,000 acre-feet (called "qualifying reservoirs") must also measure the followingApplies starting WY 2027high
#P007operationalreportingmandatoryLegacy Measuring Device Accuracyotherrequirement<= 15 percentMeasuring devices installed on or before January 1, 2016, must be accurate to within ±15 percent.Applies to devices installed on or before Jan 1, 2016high
#P008operationalreportingmandatoryMeasurement Accuracy (> 1,000 acre-feet)otherrequirement<= 10 percentVolume Threshold: More than 1,000 acre-feet | Accuracy: Within ± 10%Hourly measurement frequencyhigh
#P009operationalreportingmandatoryMeasurement Accuracy (201 to 1,000 acre-feet)otherrequirement<= 10 percentVolume Threshold: 201 to 1,000 acre-feet | Accuracy: Within ± 10%Daily measurement frequencyhigh
#P010operationalreportingmandatoryMeasurement Accuracy (11 to 200 acre-feet)otherrequirement<= 15 percentVolume Threshold: 51 to 200 acre-feet (Weekly) and 11 to 50 acre-feet (Monthly) | Accuracy: Within ± 15%Weekly or Monthly measurement frequencyhigh
#P011operationalreportingmandatoryLarge Diversion Volume Thresholdotherrequirement> 10,000 acre-feet per yearA claimed water right with a maximum allowable diversion amount greater than 10,000 acre-feet per yearSubjects diverters to Large Diversion Requirements starting October 1, 2026high
#P012operationalreportingmandatoryLarge Diversion Rate Thresholdotherrequirement> 30 cubic feet per secondA claimed water right with a maximum allowable direct diversion rate greater than 30 cubic feet per secondSubjects diverters to Large Diversion Requirements starting October 1, 2026high
#P013operationalreportingmandatoryLarge Diversion Submission Lag Timeotherrequirement<= 7 daysIn general, diverters need to submit their large diversion submissions on a weekly basis, with a lag time of no more than 7 days between the most recent measurement and the submission date.high

D Definitions (0)

No definitions.