Water Measurement and Reporting Regulation

California's recent droughts have highlighted the need for more current and accurate water diversion data on a statewide scale. Previous standards required monthly diversion totals be reported annually, but the 2012-2016 drought highlighted the limitations of such standards and their application to drought management. Even in non-drought years, rainfall and snow patterns vary widely. Adequate supply in some regions may occur at the same time as critical water shortages elsewhere, and these patterns can change throughout the year. High quality, accurate data that is collected and reported at a finer resolution is therefore essential for managing water resources throughout the state. Accurate reporting protects your water rights, helps inform both statewide and local water availability and future planning decisions, and assists in processing water right applications.

Measurement data helps improve the way California manages and allocates water rights by helping to

• Forecast and plan for limited water supplies
• Ensure compliance with permit and license terms of existing water rights
• Protect water rights based on priority year
• Provide for efficient management and use of water during times of shortage
• Improve water planning and near-term forecasting of water demand
• Facilitate collaborative solutions between the State Water Board and local water managers

In general, those who divert more than 10 acre-feet per year are required to measure and report their diversions. 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 a point of diversion and have a combined face value or historical use of more than 10 acre-feet
• Multiple water rights that share a place of use and have a combined face value or historical use of more than 10 acre-feet
• 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 reporting year. If you are unsure of the details of your water right or claim of right, please refer to the following guide: Know Your Water Right.

Refer to the Measurement and Reporting Manual for more information on who needs to measure their diversions.

Diverters must measure and report their diversion volumes by water right. In general, measurements must be accurate to within ±10 to 15 percent, depending on the size of the diversion. Refer to the Measurement and Reporting Manual for more information on measurement and accuracy requirements.

For diversions to storage, diverters must also measure each of the following:

• Volume of water diverted to storage under each water right
• Volume of water withdrawn and/or released from storage under each water right

For 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 measurements

Diverters must measure their diversions monthly, weekly, daily, or hourly, depending on the type and size of diversion. Refer to the table below for more information regarding how frequently to measure diversions. 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.

Diverters must measure their diversions using a measuring device, measurement method, or combination of these. The terms “measuring device” and “measurement method” have specific definitions in the context of this regulation that are described below. Refer to the Measurement and Reporting Manual for more information about measuring devices and measurement methods.

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. For your convenience, the State Water Board has a list of measuring device vendors.

Measurement methods are any other way of measuring diversions that do not use a “measuring device” (as defined above) to measure the volume of water diverted under a single water right. Usually, a measurement method will require some math to calculate the volume of water diverted for each water right. Here are some examples of measurement methods:

• A group of diverters each divert water from the same location, but they share a flow meter. Even though a flow meter meets the definition of a measuring device, a measurement method is needed to determine the volume diverted under each water right. The meter measures the total amount of water they all divert, so they use a measurement method to calculate the amount of water that is diverted under each of their water rights.
• A diverter uses a pump to divert water from a stream. The pump has its own dedicated electricity meter and operates at a constant rate. The diverter uses the electricity records combined with the pump specifications and pump curve to calculate the volume of water diverted.
• A diverter pumps water into a storage tank and only refills the tank when it empties. The diverter counts the number of times the tank is filled and multiplies that by the volume of the tank to calculate the volume of water diverted.

Below are some additional resources for measuring diversions:

• U.S. Bureau of Reclamation Water Measurement Manual
• Fact Sheet: Pipes and Closed Conduits
• Fact Sheet: Open Channels (including weirs, flumes, canal meter gates, non-standard structures)
• Fact Sheet: Wells
• Fact Sheet: Low Flow Rates (including battery-operated flow meters, volumetric calculations by stopwatch, pump electricity kW-h meters)
• Fact Sheet: Reservoir Diversions to Storage (including water balance calculations, measuring reservoir storage, depth-capacity curve, small reservoirs on ephemeral streams, monthly or manual water level measurement)
• Reservoir Storage Measurement and Recordkeeping Guide for Above-Ground Reservoirs (including installing a measuring device, creating a reservoir capacity curve)
• Average Cost of Measurement (last updated February 2016)
• Financial Assistance Programs (last updated November 2015)

There may be certain situations where a diverter is unable to measure their diversion as frequently or accurately as they are required. If doing so would be unreasonably expensive, unreasonably affect public trust resources, result in wasted water, or otherwise be infeasible, diverters may submit and implement an Alternative Compliance Plan (ACP). Diverters who measure and report under an ACP must meet their specified measurement requirements as much as possible and explain why they are unable to fully meet all requirements. Please refer to the Measurement and Reporting Manual for more information on how to submit an ACP.

Diverters should compile measurement data in a datafile and submit it as an attachment to their Annual Water Diversion and Use Reports. For detailed information on how to submit data, please refer to the Measurement and Reporting Manual and the Measurement Data Submission Video Tutorial.

Optional datafile templates are available below. Each template corresponds to a different measurement frequency. Please refer to the instruction manual for detailed information on how to use the templates. The State Water Board highly recommends using the provided templates to reduce unintentional reporting errors, ensure that submitted datafiles include all required components, and ensure that datafiles are in an appropriate and readable format. For diverters who opt to use a datafile format other than what is presented in the provided templates, please refer to the Datafile Best Practices and Datafile Practices to Avoid sections below for general guidelines on how datafiles should be structured.

Datafile Templates for Measurement Reporting

• Datafile Template Instruction Manual
• Datafile Template for HOURLY Measurements
• Datafile Template for DAILY Measurements
• Datafile Template for WEEKLY Measurements
• Datafile Template for MONTHLY Measurements
• Datafile Template for CUSTOM INTERVAL Measurements

Datafile Best Practices

In general, datafiles should contain the following information:

1. File type that can be opened using either Microsoft Excel or Microsoft Access (common file types include.xls, .xlsx, .csv, .txt, .dat)
2. Descriptive column headings in the first row of the datafile
3. Use only one spreadsheet “tab” with only one data table per datafile (you may submit multiple datafiles with your Annual Water Diversion and Use Report)
4. Use only one datafile per measuring device per water right/claim
5. Date and time of measurement
6. Measured value (the raw/unaltered data output from your measuring device or measurement method)
7. A separate column of QA/QC’d values correcting for known or suspected errors
8. Comments or data flags identifying any known or suspected errors
9. Volume of water diverted under the water right at each time stamp and measured value (any calculation or conversion protocols should be attached separately to your Annual Report and not included within your datafile)
10. Units written out in their entirety (i.e., not abbreviated)
    • Any standard units are acceptable. Common examples include acre-feet or gallons (for volume), cubic feet per second or gallons per day (for flow rate), feet per second (for water velocity), and feet or meters (for water elevation).

Datafile Practices to Avoid

In general, datafiles should not contain the following:

1. Images or graphs, or file types that are not machine readable, such as .pdf, .jpg, .png, .bmp, etc.
2. Unclear or missing column headings
3. Multiple spreadsheet “tabs” or data tables in a single datafile
4. Multiple datafiles for the same measuring device for the same water right/claim (e.g., do not split up data from a single device into separate datafiles by month)
5. Merged cells or multiple values within the same cell
6. Irrelevant data that does not relate to diversion measurements
7. Excessive narrative text
8. Hyperlinks to external databases

Measuring diversions can be complex, therefore a Qualified Individual must ensure that your diversions are measured accurately. A Qualified Individual is always required, regardless of whether the diversion is measured using a measuring device, measurement method, or Alternative Compliance Plan. However, the exact role the Qualified Individual performs varies depending on how the diversion is measured. Refer to the Measurement and Reporting Manual for information on Qualified Individuals and when they are needed.

The term “Qualified Individual” has a specific definition in the context of this regulation depending on the size of the diversion, as shown in the table below.

Most diverters may find it easiest to hire a Qualified Individual to help measure their diversions. For your convenience, the State Water Board maintains a list of consultants that practice in water rights. Note: The State Water Board does not endorse any of the professionals on these lists and you may find other professionals that suit your needs.

Alternatively, any diverter can become a Qualified Individual by completing a training course on measurement devices through the University of California Cooperative Extension. Please refer to the University of California Cooperative Extension website for more information, including a list of upcoming training classes and registration information.

California's State Legislature passed Senate Bill 88 in 2015, authorizing the creation of the Water Measurement and Reporting Regulation. The State Water Board held public meetings and workshops in affected areas around the state to receive input on the regulation before it was adopted in January 2016 and became effective in March 2016. The regulation is in effect until it is revised by the State Water Board. Materials from past events are available upon request by contacting DWR-Measurement@Waterboards.ca.gov.

In 2023, the State Water Board hosted public listening sessions and outreach workshops to better understand and address common questions, concerns, and other comments regarding the water measurement and reporting regulation. The staff presentations and a summary of public feedback are available below:

• Guidance Workshop – December 2023, PowerPoint Presentation
• Guidance Workshop – December 2023, Video Recording
• Public Listening Session – August 2023, PowerPoint Presentation
• Public Listening Session – August 2023, Feedback Summary

Note: Some of the materials from past events are outdated. Please refer to the Measurement and Reporting Manual for the latest information.

For more information regarding the water measurement and reporting regulation, please refer to the following resources:

• Measurement and Reporting Manual
• Frequently Asked Questions (FAQs)
• Datafile Templates
• Telemetry Website
• Alternative Compliance Plans
• SB-88 Rulemaking Information and Documentation

The State Water Board maintains lists of attorneys and consultants that practice in water rights for your convenience. The State Water Board does not endorse any of the professionals on these lists and you may find other professionals who are suited for your needs.

For additional questions and assistance, please contact Division of Water Rights staff at DWR-Measurement@Waterboards.ca.gov.