Georgetown Lake levels back above average

The water surface elevation of Georgetown Lake is above average for this time of year, based on 80 years’ worth of lake elevation data. The lake remains frozen. As of mid-February, the lake’s elevation level was at 6,428.69 ft.

That’s according to Todd Blythe with the Montana Department of Natural Resources and Conservation’s Water Sciences Bureau, who stated in his February report that “lake elevation has been slowly increasing since November due to lower outflows. In January, outflows were increased but were still lower than inflows so lake level as continued to rise into February. The lake gained the most storage (more than 800 acre-feet) in November of 2024. Last month, January, the lake gained 595 acre-feet. January average monthly outflows of 9.5 cfs were less than inflows making the average total lake inputs equal to 19.2 cfs. The inflows were 68% of normal for January.”

As to precipitation, Blythe’s report stated the Peterson Meadows SNOTEL site accumulated 2.2 inches (157% of normal) in January. Currently, the SNOTEL is showing 7.3 inches of snow (111% of normal). The Warm Springs SNOTEL site, which gives an idea of the higher elevation precipitation conditions, accumulated 3.5 inches of precipitation (100% of normal). As of Feb. 14, Warm Springs is reading 13.5 inches of snow (92% of normal). 

Blythe’s report includes the following model forecast: “I have continued to implement the new version of the Georgetown Model that allows for variable monthly inflow percentages which are shown for each month on the bottom of the graph. I used a conservative estimate of 60% normal inflows for the next 2 months with outflows set to 12 cfs. For the spring runoff season I increased the inflow percentages to better represent the current snow conditions (which are above normal based on SNOTEL sites). These inflows might also be considered conservative if snow continues to fall the rest of the winter. Under these simulated conditions the lake still fills by June with increased winter outflows greater than 10 cfs. More importantly, this gives plenty of time to adjust if conditions worsen between now and May.”