South Fork 4-1-18

Yesterday flow out of Palisades Dam was increased to 18000 cfs.  That flow makes for difficult near-term fishing. Over the last month the Palisades Dam flow graph looks like a step function, and for good reason. There is more than normal snow pack in the upper Snake River drainage.  Thus the Bureau of Reclamation placed a public announcement on April 3rd giving their Snake River water management strategy. Here is an excerpt from it that impacts the South Fork reach and the main stem Snake River to just below American Falls Dam.   Note Reclamation’s  estimate of 114% of the recent decade average.  That’s the basis for their management strategy.

Reclamation’s April through July volume runoff forecast for Heise is 3700 KAF, which is 114% of the 1981-2010 average.  To begin advancing on updated flood control targets for Jackson Lake Dam and Palisades Dam the following changes have or will be made this week. 

·       Jackson Lake Dam discharge will be increased Thursday (4/5) at 10 am from the current 630 cfs up to between 1,000 cfs and 1,500 cfs.

·       Palisades Dam discharge will be increased Thursday (4/5) evening into Friday (4/6) morning to go from the current 10,000 cfs up to between 14,500 cfs and 16,000 cfs by Friday morning.

·       American Falls Dam discharges were increased today from 11,000 cfs to 13,000 cfs.  Another increase will occur Wednesday (4/4) morning at 10 am to go from 13,000 cfs to 15,000 cfs.

The intent with respect to Palisades Reservoir is to decrease its capacity to around 50% ( Currently at about 70%) in order to contain expected run off.  More increases in flow out of these three dams are possible, with weather being a factor in determining flow management. For additional information and resources, please visit Reclamation’s website at:  https://www.usbr.gov/pn/hydromet/uppersnake/ .