With these waterways and their branches touching over half the country, it is easy to see why the GYE has been called the “headwaters of the nation.” Furthermore, the 2013 Yellowstone National Park “Vital Signs” report states that all the park’s waters are classified Outstanding Natural Resource Waters for their exceptional ecological significance and water quality.
A Good Year
But years like this one, where high snowfall totals lead to an abundance of water, are becoming the exception, not the rule. “We have these cycles of good snow years and not good snow years, and this was a big year,” says Ann Rodman, Yellowstone’s Branch Chief for Physical Resources and Climate Science, who studies weather, climate change, and snow accumulation in the GYE. “But, looking at the data from the past 35 years or beyond, the overall trend is towards a decreasing snowpack and over time these big years will become more unlikely.” This is backed up by the “2013 Vital Signs” report, which says that winters at the Northeast Entrance since 1980–as determined by the annual number of days with measurable snow on the ground –have shortened by over twenty days, or eleven percent. At Mammoth Hot Springs, since 1976, the average annual daily minimum temperature and the average annual daily maximum temperature have increased by 4.6˚F and 3.5˚F respectively. Increases in temperatures and heat waves not only mean less precipitation as snow but also faster runoff due to a shorter window of snow storage over the course of the year. According to The Greater Yellowstone Area Climate Explorer (see sidebar), historically 28 percent of the GYE watersheds have been categorized as “snow dominated,” meaning that on April 1 they still have more than 40 percent of winter precipitation stored in their snowpack. But by the middle of this century, climate models estimate that less than half of these watersheds will still be “snow dominated” on April 1.
“But years like this one, where high snowfall totals lead to an abundance of water, are becoming the exception, not the rule.”
“This change is reflected in what we are seeing as snow starts to melt earlier and faster. Now when you hit the peak snowpack you have a shorter period of time until it all melts,” says Rodman. “This will mean a dramatic change in the amount of water stored as snow and the timing and amount of snow melting the spring. This runoff supplies most of the water that the park and everybody downstream depends on throughout the summer.”
In an effort to safeguard the park’s watershed in the face of this change in climate, the National Park Service included a “water” section in their strategic plan for sustainablity designed to protect Yellowstone’s watersheds as well as the park’s natural hydrological and geothermal features and potable water supply. Some projects in this widespread conservation effort are preventative, such as increased monitoring for leaks in the park’s infrastructure. Others are more proactive, like installing an upgraded irrigation system on the 12 acres of historic lawn in Mammoth Hot Springs.
“Now we water the grass with an automated system that uses water based on current weather, not a set time of day,” says Molly Nelson, a member of the park’s Green Team and an NPS engineer who worked on this project. “So far, we’ve seen a 20 percent water savings since 2011 and eventually expect that to rise to 30 percent when the project is finished.” Park personnel are also experimenting with new technologies and design techniques to reduce the impact of paved surfaces on water resources, which entails trying out test patches of 4