Every Drop Counts: Low snow, low flow 

By Jack Buban EBS COLUMNIST 

It was hard to get on a chairlift this year and not hear locals’ complaints about the lack of snow cover. Snowpack is both the lifeblood of the water resources in Big Sky, and what gives life to our winter recreation.  

According to a Water Budget report commissioned by the Gallatin River Task Force and completed by WGM Group, our snowpack accounts for roughly two-thirds of the total precipitation that Big Sky receives annually. Snowmelt throughout the spring and summer feeds our rivers and groundwater aquifers, replenishing vital freshwater that we rely on for irrigation, recreation and community drinking water.  

Making sense of snowpack can oftentimes be a difficult task, with acronyms like SNOTEL (Snowpack Telemetry, a national system for determining water and snowpack levels) and SWE (Snow Water Equivalent) being tossed around in conversation and cited articles, leading to more questions than answers. We’re really trying to determine two things, through all the science and science-related jargon: how the lack of snow affects summer streamflow, and whether all this spring snow made up for the dry winter and low snowpack.   

Late spring snow arrived in force this year and seemed like it wouldn’t stop. With over a foot falling just before Memorial Day weekend, Big Sky looked for a while like we may have been out of the woods after a historically warmer, dryer winter. However, comparison to historical averages via SNOTEL becomes less reliable late in the spring, as the rate that snow falls and melts is different from year to year, making averages at this time of year difficult to capture. In reality, significantly less precipitation has occurred this water year and we are still in a deficit.  

Unfortunately, large spring snowstorms don’t always offset prior drought. By incorporating last season’s snowfall and tracking upcoming weather patterns and trends, scientists can model what to expect from a streamflow perspective for the upcoming season, but can’t always accurately predict how precipitation in the spring can offset the deficit from the winter snowpack. That is precisely what Eric Larson, a water supply specialist at the Natural Resource Conservation Service, did when predicting what the summer outlook for water in the Gallatin River Basin might look like this year.  

Without being able to predict exactly how much rainfall we will see this summer, it is likely that we may still only see enough precipitation to bring the Gallatin River Basin up to 65 to 85% of its average streamflow. Even in the most optimistic models—where we receive above average amounts of rainfall—the Gallatin River Basin is still only expected to reach 85 to 95% of average streamflow.  

All of this is happening while Big Sky remains in a state of moderate drought, determined by many factors including streamflow. On the ground this means a handful of things, with the effects of drought being felt by everyone, from ranchers to recreationists and natural resource management agencies. Low snow means low flow, which can lead to fishing closures, limited water use for community sources, and restricted uses for downstream irrigators in the Gallatin Valley.  

Seasonal drought is expected to persist and is something our community should be prepared for—at any and all levels. Small things like mindful landscape irrigation practices, specifically watering during the cooler hours of the morning and evening, can go a long way to helping our community be more resilient during drought events like this that are being predicted for this summer and into the future.  

The 2023-24 winter was far from the wettest we’ve seen in Big Sky’s history; in fact, many would claim it as one of the dryest. And the effects of that are going to persist long after all the snow has melted. Experts anticipate low streamflow in the Gallatin this year, affecting lifestyles and livelihoods of people and wildlife that rely on this river.  

Unfortunately, low snow years and drought aren’t expected to be going away anytime soon, with scientists tracking a decline in snowpack throughout the Mountain West over the last 70-plus years, and predicting that this trend will continue in the future.  

In the face of the scientific evidence and predictions related to a changing climate, we have a responsibility in this community to adapt, to be mindful and to gain awareness about becoming a more drought- and climate-resilient community in the face of ever-changing weather conditions we are sure to face.  

Jack Buban has spent two years as the Watershed Corps member with the Gallatin River Task Force.