Updated October 2, 2017

A nice snow storm to kick off the 2018 Water Year!  For the 2017 Water Year, Peterson Meadows received a total of 26.3 inches of precipitation, which is 114% of normal.  However, there was zero precipitation during August and only 0.5 inch during July.  February through June all received above-normal precipitation.  Overall this past summer, Georgetown Lake and Flint Creek fared better than just about any other watershed in Montana. New end-of-month water surface elevation records were set for June (6430.09 feet) and July (6429.71 feet).

The water surface elevation currently sits at 6428.78 feet, which is about 0.6 feet (7 inches) above the long-term normal for this time.  For September, reservoir outflow averaged 44.3 cfs and the reservoir lost 922 acre-feet of storage. Further calculations show that September lake inputs averaged 28.8 cfs, which is 132% of the long-term average.  Colder air temperatures and timely precipitation not only added water, but reduced evaporative losses.

Current CPC forecasts show elevated chances of above-normal precipitation for October through February.  

I ran the model based on continuing inputs of 132% of average (see attached JPG).  At this time, the focus should be on the next few months however, and getting the lake to a suitable level for freeze-up, which is typically in mid to late November at 6428.20 to 6428.50 feet.

 

Thanks, Dave

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