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173-508-050  <<  173-508-060 >>   173-508-070

PDFWAC 173-508-060

Instream flows for the Cedar River.

(1) The instream flows established in this section apply to waters of the Cedar River and affect the entire watershed drained by the Cedar River including all tributaries thereto.
(2) Instream flows established in this section shall be measured at the existing U.S. Geological Survey gaging station No. 12.1190.00 on the Cedar River at Renton, Washington.
(3) Except as provided herein (critical year flows), water flows in the Cedar River and tributaries thereto shall, to the extent depletion under existing rights and natural flow conditions permit, be maintained throughout each year at levels which, during the time periods designated, do not fall below the following measurements:
(a) Normal Year Flow
January 1 to June 20:
370 cfs
June 20 to July 15:
Linear decrease from 370 cfs on
June 20 to 130 cfs on July 15
July 15 to September 10:
130 cfs
September 10 to September 20:
Linear increase from 130 cfs on September 10 to 200 cfs on September 20
September 20 to October 1:
200 cfs
October 1 to October 10:
Linear increase from 200 cfs on October 1 to 370 cfs on October 10
October 10 to January 1:
370 cfs
Normal year flows must be maintained at all times unless a critical condition is declared by the director. If natural Cedar River flows fall below the 1 in 10 year Cedar River flow frequency, the director, or his designee, may authorize flows below the normal year flows, but not lower than the critical year flow except where a declaration of overriding considerations of public interest is made by the director. All requests to deplete below the established instream flow level will be considered on a case-by-case basis.
(b) Critical Year Flow
January 1 to June 15:
250 cfs
June 15 to July 1:
Linear decrease from 250 cfs on June 15 to 110 cfs on July 1
July 1 to October 1:
110 cfs
October 1 to November 1:
Linear increase from 110 cfs on October 1 to 250 cfs on November 1
November 1 to January 1:
250 cfs
Critical year flows represent flows below which the department believes substantial damage to instream values will occur. Critical year flows are expected to be met unless natural Cedar River flows fall below the one in fifty year Cedar River flow frequency.
[Statutory Authority: Chapters 90.22 and 90.54 RCW. WSR 79-10-002 (Order DE 79-9), ยง 173-508-060, filed 9/6/79.]
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