2017

Happy New Year to the Water Towers of Wyoming!

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Happy New Year – Water Year That Is

Across the Water Towers of Wyoming, October 1st of each year is a watershed moment, literally and figuratively. This is because the first day of October marks the beginning of a new water year. So Happy New Year to the Water Towers of Wyoming (Photograph 1)!

Photograph 1. Early fall storm clouds build over the Absaroka Mountains in western Wyoming. Across the high elevations of the State, annual snowpack begins to build around October 1st. This is the start of a new water year. Snow continues to fall through the winter and early spring, forming a deep white layer across the landscape. The deep snow melts in late spring and early summer. The melted snow becomes an ecosystem service to people within and downstream of the water towers.

What is a Water Year

“Water year” describes a years worth of precipitation. The time period for the water year depends upon the part of the world where the precipitation is being measured. In the water towers of Wyoming, the “water year” begins October 1st of one year and ends September 30th of the next. So, October 1st, 2017 through September 30th, 2018 is Water Year 2018.

Hydrologists and water managers in Wyoming use water years because year after year there is strong correlation between snowpack accumulation and streamflow (Figure 1).

Figure 1. Precipitation is measured in Wyoming’s mountains by staff working for the Natural Resource Conservation Service. The staff installs SNOTEL sites at strategic locations. Instruments at these sites measure precipitation and snowpack depth and water equivalence. This graph shows data, for Water Year 2017, collected at the Kirwin SNOTEL site in the Absaroka Mountains(snow covered area in Photograph 1) west of Meeteetse, Wyoming.

Water Year 2017

Water Year 2017 was exceptionally wet across all the water towers in Wyoming. For example, in the Kirwin area (Figure 1) thirty-six inches or three feet of precipitation was measured. The long-term average is about twenty-four inches or two feet. So, this area received twelve inches more precipitation than average.

The water year was also a huge snowpack year. Snow water equivalence or the amount of water in the snow was twenty-six inches or over two feet. The long-term average snow water equivalence is about eleven inches or just under one foot. So, this area received over twelve inches more snow water equivalence than average.

To appreciate the magnitude of water year 2017, on average, one foot of newly fallen snow contains one inch of water equivalence. So, on average the Kirwin SNOTEL site receives about eleven feet of snow every winter. In water year 2017, twenty-six feet of snow accumulated. That’s 312 inches. WOW!!

Water Year 2018

We won’t know how water year 2018 will stack up against water year 2017. Nor will we know how it will stack up against the long-term average. Only time will tell.

In the meantime, celebrate the new water year by getting out and enjoying your public lands. They are your lands after all.

Until next time…CHEERS and HAPPY NEW YEAR!!!

 

 

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