On January 19, 2016 the California State Water Board adopted an SB-88: Emergency Regulation for Measuring and Reporting Water Diversions. The key provisions of the regulation call for all water rights holders to report their diversion and use of water annually. As the size of water diversion increases, the more stringent the measurement and monitoring are the requirements. SB-88 follows of the pattern of many Rocky Mountain states already requiring that individual water rights holders measure and report their usage amounts.
As a practical matter, SB-88 means that many users who had not previously been subject to measurement and reporting measures are no required to do so. Depending upon water usage, the required device accuracy varies from 10-15%, with monitoring frequency from hourly to monthly.
How Do Flumes Apply to SB-88?
Flumes are dimensionally fixed hydraulic devices that do not require field calibration or rating. So long as the flume is installed correctly, adheres to the published dimensions, and is not submerged due to downstream conditions, no additional rating need be done. Even should a flume shift out of position or become submerged due to downstream conditions, corrections have been developed for certain flume types to correct the level/flow readings.
Also, properly installed, open channel flumes can be expected to exhibit a measurement accuracy of +/- 8-10% (within even SB-88’s most stringent requirement).
Level (and flow) reading can be taken manually though the use of a staff gauge in the flume – or by surveying stick. For installations where more frequent monitoring is required, flumes can be outfitted with low cost pressure transducers that automatically record the flow rate.
Which Types of Flumes are Used?
Parshall and Cutthroat flumes are the two most commonly used.
The Parshall flume began development in the 1920’s for exactly this purpose: measuring water rights and surface water flows.
The Cutthroat flume is a later development (1970’s), and is the result of trying to overcome certain deficiencies that are present in the Parshall flume. Of the two, the Parshall flume is the most common, while the Cutthroat flume is best suited for retrofitting into relatively flat channels.
How Can Openchannelflow Help?
Your local Openchannelflow California representative – Kent Bricker of Southland Water Technologies (800–795-5231) has been working with SB 88 water users to develop cost effective monitoring and reporting solutions.
Contact Kent today to see how Southland Water Technologies and Openchannelflow can help you get in compliance.
