PDFWAC 173-549-020
Establishment of minimum instream flows.
(1) Minimum instream flows are established for stream management units with monitoring to take place at certain control points as follows:
Stream Management Unit Information
Stream Management Unit Name, Control Station Name and Number | Control Station Location by River Mile, Section, Township, Range | Affected Stream Reach | |
Lower Okanogan | |||
Okanogan R. at Malott (12447200) | 17.0, 9-32-25E | Okanogan River confluence with Wells Pool to confluence of Chewiliken Cr. | |
Middle Okanogan | |||
Okanogan R. nr. Tonasket (12445000) | 50.8, 8-36-27E | Okanogan River confluence of Chewiliken Creek to confluence Similkameen River | |
Upper Okanogan | |||
Okanogan R. at Oroville (12439500) | 77.3, 27-40-27E | Okanogan River confluence of Similkameen River to Osoyoos Lake | |
Similkameen | |||
Similkameen R. at Nighthawk (12442500) | 15.8, 7-40-26E | Similkameen River confluence with Okanogan River to Canadian Border | |
(2) Minimum instream flows established for the stream management units in WAC 173-549-020(1) are as follows:
Minimum Instream Flows in the
Okanogan River
(All Figures in Cubic Feet Per Second)
Month | Day | Lower Okanogan 12447200 | Middle Okanogan 1244500 | Upper Okanogan 124426000 | Similkameen 12439500 | ||||
Jan. | 1 | 860 | 800 | 320 | 400 | ||||
15 | 830 | 800 | 320 | 400 | |||||
Feb. | 1 | 820 | 800 | 320 | 400 | ||||
15 | 850 | 800 | 320 | 400 | |||||
Mar. | 1 | 880 | 800 | 320 | 425 | ||||
15 | 900 | 800 | 320 | 450 | |||||
Apr. | 1 | 925 | 910 | 330 | 510 | ||||
15 | 1,100 | 1,070 | 340 | 640 | |||||
May | 1 | 1,750 | 1,200 | 350 | 1,100 | ||||
15 | 3,800 | 3,800 | 500 | 3,400 | |||||
Jun. | 1 | 3,800 | 3,800 | 500 | 3,400 | ||||
15 | 3,800 | 3,800 | 500 | 3,400 | |||||
Jul. | 1 | 2,100 | 2,150 | 420 | 1,900 | ||||
15 | 1,200 | 1,200 | 350 | 1,070 | |||||
Aug. | 1 | 800 | 840 | 320 | 690 | ||||
15 | 600 | 600 | 300 | 440 | |||||
Sept. | 1 | 620 | 600 | 300 | 400 | ||||
15 | 700 | 600 | 300 | 400 | |||||
Oct. | 1 | 750 | 730 | 330 | 450 | ||||
15 | 960 | 900 | 370 | 500 | |||||
Nov. | 1 | 950 | 900 | 370 | 500 | ||||
15 | 950 | 900 | 320 | 500 | |||||
Dec. | 1 | 930 | 900 | 320 | 500 | ||||
15 | 900 | 850 | 320 | 450 | |||||
(3) Minimum instream flow hydrographs, as represented in WAC 173-549-900, shall be used for definition of minimum instream flows on those days not specifically identified in WAC 173-549-020(2).
(4) Future consumptive water right permits hereafter issued for diversion of surface water from the mainstem Okanogan River and the Similkameen River shall be expressly subject to minimum instream flows established in WAC 173-549-020 (1) through (3) except those described in WAC 173-549-070.
(5) Projects that would reduce the flow in a portion of a stream's length (e.g. hydroelectric projects that bypass a portion of a stream) will be considered consumptive only with respect to the affected portion of the stream. Such projects will be subject to instream flows as specified by the department. These flows may be those established in WAC 173-549-020 or, when appropriate, may be flows specifically tailored to that particular project and stream reach. When studies are required to determine such reach- and project-specific flow requirements, the department may require the project proponent to conduct such studies.