Georgetown Lake Update 3-15-2018

The lake level this winter has been fluctuating around 6428.35 feet, which is perfect.  Outflow has also been pretty steady at around 30 cfs.  Normal winter outflow is only about 16 cfs, so outflow has been high in order to keep a steady lake level with an abundance of moisture in the system.

 The lake level was 6428.34 feet on January 31 and 6428.31 feet on February 28.  Therefore, February inputs to the lake averaged a healthy 28.6 cfs, which is 122% of normal.  Last week, the NRCS released its’ early March Water Supply Outlook. The snowpack for Flint Creek, including SNOTEL sites and manual snow courses, was calculated as 157% of normal.  Today, just looking at the Peterson Meadows and Warm Springs SNOTEL sites, snow water equivalent is approximately 181% of normal. So, a lot of snow, a lot of snow water equivalent, and a forecast calling for more this evening and tomorrow.

 

 The NRCS Water Volume Forecast for Flint Creek at Southern Cross is 158% of normal at the 50% chance of exceedance (best estimate at this time), for April through September.  There is also a 30% chance of exceeding 177% of normal.  Right now, there is even a 90% chance of exceeding 106% of normal. 

 

 For now, I modeled the “best estimate” only.  We still have winter, especially at higher elevations, and snowpack typically peaks in the upper basin in early May.  Attached is the model run for 158% of normal conditions. Keep in mind that the model output shows 158% for all months.  In reality, the 158% of normal is a seasonal volume estimate.  Therefore, some month-end elevations and inflows (March, April) will be overestimated by the model; some months (May, June, July) will possibly be underestimated.

 

 At this time, we don’t know how or when the snow will come off.  But with the existing snowpack I think it’s a good time to start thinking about high water storage/release strategies.

 

 Thanks, Dave

 


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