Wednesday, March 6, 2013

US NRCS March "Basin Outlook Report"

The Idaho Office of the US NRCS yesterday released their monthly "Basin Outlooks Report."  Here is the relevant narrative for The Salmon River:

"For a whole, the Salmon basin snowpack decreased from 101% of median a month ago to 91% on March 1. Snowpacks in the Salmon River tributaries range from a low of 77% of median in the low elevation Little Salmon to normal conditions in the Lemhi basin. The MF Salmon River and most other tributaries are in the 90-95% of normal range. 

With the lack of precipitation the past two months, streamflow forecasts continued the downward slide throughout February, down another 10-20 percentage points from last month. The Salmon River near White Bird is forecast at 5,150,000 acre-feet, 87% of average. This would equate to 79% of the 1971-2010 average value. River runners and water users need to get used to the new normals. 

The higher percentages are a lot like river runner stories; you need to decipher the facts from the inflated percentages or numbers. Overall, this year’s runoff will still be promising; the volumes will not be as high last year. There are still six to eight weeks left in the snowpack accumulation season in these central mountains, so let’s hope this roller coaster precipitation pattern bottoms out and starts climbing again. Peak flows and timing of runoff are spring weather dependent."

You can read the full statewide document below or click here to obtain the file from the US NRCS FTP Server:

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