Instream Flows Policy



These FAQs will be updated periodically. The last update was on April 17, 2008. Specific questions may be directed to Division of Water Rights staff via email at or via telephone at (916) 341-5342.

    Assembly Bill 2121 (stats. 2004, ch.943, § 3), added Water Code section 1259.4 which requires the State Water Board to adopt principles and guidelines for maintaining instream flows in northern California coastal streams as part of state policy for water quality control, for the purposes of water right administration. The State Water Board released a draft policy on December 28, 2007, with modifications dated January 7, 2008 and March 14, 2008. Once adopted, the policy will implement Water Code section 1259.4.
    The upper limit of anadromy is the upstream end of the range of anadromous fish that currently are, or have been historically, present year-round or seasonally, whichever extends the farthest upstream. The draft policy's minimum bypass flow criteria allows the use of the watershed drainage area at the upper limit of anadromy for calculating the minimum bypass flow at points of diversion that are above the upper limit of anadromy. The location of the upper limit of anadromy is also considered when selecting points of interest to evaluate the proposed project's effect on fishery resources.