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Bear Lake Water Supply

The News-Examiner of Montpelier, Idaho

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The outlook for a good runoff into Bear Lake just keeps getting worse -and worse - and worse. In early January, water things looked pretty "normal". Snowpack was above average, runoff was forecast at 85% and the soil moisture was quite high. By early February, this report would have been very short. The temperatures had been 10 degrees above normal, the snowpack had decreased to 74% and the runoff forecast was down to 70%.

By early March, I couldn't force myself to write any kind of summary - too gloomy to send out. Northern Utah had very little snow, record warm temperatures (the hottest Feb and March on record) and record low snow packs. We even had runoff recorded in January! The only two positive trends were that stream flows were near normal and soil moisture content was very high.

We interrupt this lake level report... this just in, facts about snowmelt from Randy Julander, NRCS SNOTEL guru and Brian Mcinerney NOAA stream flow guru.

Most snowmelt is caused by shortwave solar radiation. A much smaller percentage is caused by heat, but if the heat is combined with wind, the snow sublimates. Two other factors include the relative humidity and the ground temperature. Larger (deeper) snow packs take longer to melt than smaller, shallower snow packs. Historically, Smaller snow packs see melt out finish earlier but about 40% of the stream flow comes after the melt out.

Larger snow packs, on the other hand, delay the peak runoff but most of the runoff comes before melt out. Once melt out has occurred, steam flow decreases quickly. Back to the report...

The situation in northern Utah this year can be summed up easily. We didn't get much snow (I.e. a near record low snow pack)! Looking at historical comparisons, only 1934 and 1977 were drier. What precip we did get was rain at the lower and mid elevations (hence the near normal stream flows and record high soil moisture content through the winter). The high level snow, while not deep, has not started to melt. So despite the record temperatures and the small snow pack, unless we get a prolonged warm wind, we should not be faced with an abysmal runoff.

The worst net runoff into Bear Lake was 0.39 ft in 1977! We are already at 1.13 ft (the 12th worst year) with runoff yet to come! At this point, our hope lies in a wet cool prolonged spring.

Lake level - so far As of 3/25 Bear Lake was at 5,913.23 ft. (UP&L datum).

That is up 1.13 ft from last year's low.

We'll get PacifiCorp's forecast for lake elevation and irrigation allocation at the Bear Lake Preservation Advisory Committee meeting in Logan on April 7th @10am at the Bridgerland Applied Technology campus

The April forecast comes out within 5 or 6 days. We'll update you then on what we learn.

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Original Publication Date: April 8, 2015

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