WAC 173-173-130   What are the specific requirements for measuring systems on open channels?  The following requirements apply to weirs, flumes, ramps and orifices. For other devices, the department will determine specific requirements on a case-by-case basis.

     (1) At any flow rate measured by the measuring system, i.e., the measuring device plus any secondary equipment such as data recorders, the system shall register not less than ninety percent, nor more than one hundred ten percent, of the water actually passing through the system.

     (2) In determining a stage-discharge relation for these devices, the distribution of open channel flow measurements shall be sufficient to establish a full range of values for the entire stage-discharge relation.

     (3) For other conditions necessary to ensure accurate and precise data, generally accepted industry standards, such as those in the U.S. Bureau of Reclamation "Water Measurement Manual, Third Edition" and information from the manufacturer or designer, shall guide the selection, installation, and maintenance of measuring devices and facilities by water users. The department also shall use these standards in evaluating the selection, installation, operation and maintenance of the measuring system.



[Statutory Authority: RCW 90.03.360, 90.44.050, [90.44.]250,[90.44.]450 and chapter 43.21A RCW. 02-02-017 (Order 00-01), § 173-173-130, filed 12/21/01, effective 1/21/02.]