A Look to the Upper South Fork Boise

Posted by admin on April 18, 2010   |  Comments Off on A Look to the Upper South Fork Boise

A couple of warm days signals the beginning of spring run-off.  And a set of charts assembeld above provides insight on what the near term holds for Anderson Ranch Reservoir.  And there are implications for the South Fork Boise downstream of Anderson Ranch Dam.

The first chart shows the inflow to Anderson Reservoir at Featherville.  The flows have started to increase and are converging towards the long term average.

The second chart shows a very small change to the contents filling Anderson Reservoir. The amount in the reservoir is above average.

Looking at the Water Year so far (water year starts October 1) we see that water in Anderson Ranch is well ahead of last year and the long term average.  But, the rate of filling appears to be behind because major melting was delayed until mid April.

Finally, here is a comparison of the amount of snow at Trinity Mountain for 2010 and 2009.  At this time last year there was more snow in 2009.  And 2009 was a below average year.

In summary there is more water in the reservoir than last year at this time but less snow in the hills.  It’s a below average year for precipitation so water managers will hold the water back as long as possible so Anderson Ranch may stay at 600 cfs into June.  We’ll ask the Bureau of Reclamation but you heard it here first.

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