OAR 690-085-0015: Methods for Measuring and Computing Water Use

(1) Beginning October 1992, methods shall be approved in advance by the Department except those prescribed in sections (4) and (5) of this rule which are approved by the Department. The methods prescribed in sections (4) and (5) of this rule are designed to meet OAR 690-085-0010(3). Alternate methods will be accepted by the Department if the conditions specified in section (6) of this rule are met. Any method is subject to review by the Department. (2) In Critical Groundwater and Serious Water Management Areas measuring requirements may be different. In such cases the more stringent measuring requirements will take precedence. (3) Where practical, water use shall be measured at each point of diversion. However, measurements may be taken at a reasonable distance from the point of diversion if the following conditions are met: (a) The measured flow shall be corrected to reflect the flow at the point of diversion. The correction will be based on periodic flow measurements at the point of diversion taken in conjunction with flow measurements at the usual measuring point; (b) If the measured flow includes flow contributions from more than one point of diversion, the measured flow shall be proportioned to reflect the flow at each point of diversion using the method prescribed in subsection (a) of this section; (c) A description of the correction method shall be submitted with the annual report the first time it is used and any time it is changed, or once every five years, whichever is shorter. (4) Approved methods for measurements made in open channels are as follows: (a) The following requirements apply for all approved methods of measurement in open channels: (A) Copies of all measurement notes, rating curves, and calculations shall be retained for three years and made available to the Department upon request. For each method of measurement, installation, and measurement procedures shall be as described in the references listed in subsection (4)(f) of this rule; (B) Channels shall be equipped with a staff gage and/or a continuous stage recorder which shall be installed in a location that provides an accurate reading of the control crest depth at all elevations and as described in the references listed in subsection (4)(f) of this rule. If only a staff gage is installed, an observer shall read the staff gage and record the reading at uniform intervals, and as close as practical before and after the time regulation of the diversion flow rate occurs. At no time shall the periodic interval be greater than three days. A continuous stage recorder may be used in lieu of periodic staff gage readings; (C) The method of measurement shall conform with the U.S. Geological Survey method for velocity-area measurements as described in the references listed in subsection (4)(f) of this rule; (D) Where practical, the rate of flow may be determined by measuring the amount of time needed to fill a container of known capacity; (E) For very low flows that cannot be measured by any of the above methods, the rate of flow may be determined by setting a portable weir or flume in the channel. The weir or flume shall be installed as described in the references listed in subsection (4)(f) of this rule; (F) Once a rating curve has been established, computation of reported monthly volume shall be as described by references listed in subsection (4)(f) of this rule with additional information available from the Department. (b) The Velocity-area Method: (A) A rating curve for the control shall be established and maintained as described in references listed in subsection (4)(f) of this rule. The distribution of open channel flow measurements shall be sufficient to establish a full range of values for the entire stage-discharge relation. Close attention shall be given to the upper end (high flows) and the lower end (low flows) of the curve; (B) Open channel flow measurements shall be taken at least once every six weeks, and at any time there is a change in channel conditions which may alter flow conditions across the control; (C) Readings taken from a staff gage shall be consistent with paragraph (4)(a)(B) of this rule. (c) The Weir Method: (A) A weir shall be installed and maintained as described in the references listed in subsection (4)(f) of this rule. Upstream from the weir a staff gage and/or continuous stage recorder shall be installed in a location that measures static head above the weir crest at all elevations and in accordance with the references listed in subsection (4)(f) of this rule; (B) When only a staff gage is installed, reading of the staff gage shall be consistent with paragraph (4)(a)(B) of this rule; (C) A rating curve shall be established for the weir as prescribed for the Velocity-area Method in paragraph (4)(b)(A) of this rule; (D) Open channel flow measurements shall be taken at least once every eight weeks, and at any time there is a change in channel conditions which may alter flow conditions across the weir. (d) The Flume Method: (A) A flume shall be installed and maintained as described in the references listed in subsection (4)(f) of this rule. A staff gage and/or continuous stage recorder shall be installed upstream from the flume in a location that measures static head and in accordance with the references listed in subsection (4)(f) of this rule; (B) When only a staff gage is installed reading of the staff gage shall be consistent with paragraph (4)(a)(B) of this rule; (C) A rating curve shall be established for the flume as prescribed for the Velocity-area Method in paragraph (4)(b)(A) of this rule; (D) Open channel flow measurements shall be taken at least once every eight weeks, and at any time there is a change in channel conditions which may alter flow conditions through the flume. (e) For a diversion monitored by the Department or a U.S. Geological Survey gaging station, it is sufficient to report: (A) The gaging station number if the station is at the point of diversion; or (B) The gaging station number and the appropriate correction, per section (3) of this rule, for adjustment back to the point of diversion, if the station is a reasonable distance from the point of diversion; (C) The current operation of any station by the Department or U.S. Geological Survey does not guarantee the continued operation or usage of the station for water use reporting purposes. (f) The following references provide guidance and requirements for the methods and installations prescribed in this rule: (A) “Measurement and Computation of Streamflow,” Volumes 1 and 2, 1982, USGS WSP 2175; (B) “Techniques of Water-Resources Investigations of the United States Geological Survey,” Book 3, Chapters A6–A8, A10, A13, and A14; (C) Water Measurement Manual, U.S. Department of the Interior, Bureau of Reclamation. (5) Approved methods for measurements made in pipes are as follows: (a) The Flow Meter Method: (A) The flow meter shall be capable of recording cumulative volume; (B) The flow meter shall be capable of measuring the full range of discharge from the source of water for which it is to be used; (C) The flow meter shall be installed and maintained according to the manufacturer’s specifications and in such a manner that there shall be a full pipe of water at all times during which water is being pumped; (D) There shall be no diversions of water between the source of water and the flow meter installation; (E) The manner in which the flow meter has been installed is subject to inspection and approval by the Director; (F) In the case of flowing artesian wells with pumps, the flow meter shall be installed in a manner which will allow measurement of both pumped and flowing discharge. (b) The Power Consumption Method: (A) This method shall not be used for flowing artesian wells; (B) A power meter shall be dedicated to one pump only; (C) The ratio of electric power consumption per quantity of water pumped shall be determined annually by physically measuring the volume of water pumped during a two-hour test. The test shall be conducted under normal operating conditions; (D) A record of the method and equipment used to determine the ratio of power consumption to volume of water pumped, and the monthly power readings for each well shall be retained for three years. The record shall be made available to the Department upon request. (c) The Time of Operation Method: (A) This method shall not be used for flowing artesian wells; (B) A meter that accumulates operating time of the pump shall be installed and dedicated to one pump only; (C) The volume of water pumped per unit time shall be determined annually by physically measuring the flow during a two-hour test. This test shall be conducted under normal operating conditions; (D) A record of the method and equipment used to determine the volume of water pumped per unit time and the monthly accumulated operating times shall be retained for three years. The record shall be made available to the Department upon request. (6) Alternate methods for reporting water use: (a) An alternate method may be used if a registered professional engineer certifies to the Department that the method will report water use within an accuracy of plus or minus 15 percent. The governmental entity shall submit a description of the method and the certification by the registered professional engineer to the Department; (b) The Department may review any alternate method at any time and may require modification to the method if the Department determines that the method does not accurately report water use as required in OAR 690-085-0010(3). [Publications: Publications referenced are available from the agency.]