Swan Falls Monitoring and Measurement Program IDWR Goals and Perspectives Presented by Sean Vincent January 24, 2012

Goals 1.Facilitate determination of “average daily flow” as defined in paragraph 7B of the 1984 Agreement** –Need to consider reservoir operations because Idaho Power reservoirs are not strictly run-of-river –Beyond factoring out operations, method for determining “actual flow conditions” is not specified **Agreement on IDWR website ( 2.Transparency 3.Inform policymakers (accuracy/uncertainty of measurements, significance of fluctuations, etc.)

Subject to I.R.E. 408 Swan Falls Agreement Paragraph 7B

IDWR Perspective Priority is to develop accurate, transparent, and scientifically defensible method –Accuracy is most important at/near the minimum flows 3,900 cfs from April 1 through Oct-31 5,600 cfs during non-irrigation Idaho Power and USGS have strong gaging capabilities (staff, equipment, training, etc.) and have experience working collaboratively Good first steps but suggestions for improvement are welcomed

Complexities Gains/losses and diversions affect flow at Murphy –Water District 02 will help to quantify diversions –Seepage study will help to quantify gains/losses Lag time for impacts caused by reservoir operations Other measurement issues –Aquatic growth –Backwater effects –CJ Strike has two arms –Location of river/reservoir interface not well defined –Wide range of flows (max at Murphy = 47,300 cfs) –Wind effects

Specific Concerns Locating upstream gages requires balancing of factors: –Favorable physical characteristics for making measurements of inflow to the reservoir –Proximate the dam to avoid introduction of uncertainty and complexity from diversions and reach gains/losses to/from Snake River and to/from reservoirs Public perception –Avoid potential appearance of bias Accuracy of Murphy gage

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