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Swan Falls Monitoring and Measurement Program IDWR Goals and Perspectives Presented by Sean Vincent January 24, 2012. Goals. Facilitate determination of “ average daily flow ” as defined in paragraph 7B of the 1984 Agreement**
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Swan Falls Monitoring and Measurement Program IDWR Goals and Perspectives Presented by Sean Vincent January 24, 2012
Goals • 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 (http://www.idwr.idaho.gov/) • Transparency • Inform policymakers (accuracy/uncertainty of measurements, significance of fluctuations, etc.)
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