Water Wisdom: Supply-side conservation

By David Tucker EBS CONTRIBUTOR

As you may or may not know, the Big Sky Water and Sewer District is looking for another source of quality, accessible water on Lone Mountain for the Mountain Village. Household water comes from groundwater sources throughout the area, and while these sources are not rapidly declining, they likely will not be enough for projected growth, especially considering warming temperatures and a declining snowpack.

“Up to this point, there is no alarming downward trend in our local aquifers,” said Mike Richter, a Montana Bureau of Mines and Geology research specialist. “We watch the water levels with our long-term monitoring network, available to the public through our Ground Water Information Center website. What we see in Big Sky is groundwater levels closely tied to precipitation and snowpack.”

BSWSD draws all of its water supply from aquifers in the Meadow and Mountain villages, and while these sources see good recharge from deep winter snowpacks, projected consumption puts the pressure on to find more soon. So far, the district has not found a large source of easily accessible clean water, and so their quest continues.

While the effort does not include surface waters like the Gallatin River and its tributaries, groundwater withdrawal can be connected to decreased surface water flows, and we are learning more about the connection between the two all the time.

“Groundwater and surface water used to be thought of as different resources,” Richter said. “But now we know it’s a single system.” Locally, “surface waters are naturally losing water into the aquifer at the top end of the system, and gaining water lower down. The relationship is heavily dependent on our geology and topography,” he said.

Because of this connectivity, withdrawal could start intercepting groundwater recharge, decreasing groundwater flow and changing the surface-groundwater relationship. “Stretches of streams gaining water from groundwater tend to be where fish seek refuge from temperature extremes, meaning they’re essential for healthy fisheries,” Richter added.

Healthy fisheries are essential for our community, which is why drought-planning and building a resilient water supply are critical. “That’s where conservation becomes so important—we need things in place before the next drought cycle,” Richter advised.

Planning for drought is challenging, and even above-average snow years can lead to dry, low-flow summers. In 2018, the Gallatin Watershed’s snowpack was well above average in late winter. By early summer, several hot, dry months had melted most of the snow and all that water ran off downstream, leaving us low and dry. This winter, we sit at 116 percent of normal on March 5, but who knows what spring has in store?

One way BSWSD is encouraging conservation is through its tiered water rates. Summer water use is at least seven times higher than winter, due largely to landscaping irrigation. The new tiered system hopes to discourage excess water use with higher rates once a user goes above a certain threshold. The Gallatin River Task Force also encourages conservation through a rebate program for residents, wherein participants get paid to upgrade their water-using appliances to more efficient models.

While these measures likely are not enough to keep BSWSD from needing another supply of water, it is a critical tool for a functioning community. “The cheapest, most river-friendly water they can find is the water people don’t use,” Richter said, reinforcing the notion that conservation is the best way to combat the worst case of a supply shortage.

For now, abundant snowfall continues to keep the Meadow Village aquifer full and clean. Surface waters are sufficiently recharged by groundwater flows, keeping fish happy and healthy. Happy and healthy fish are keeping anglers engaged and entertained. But all this doesn’t mean we shouldn’t keep our eyes on the future, because we aren’t certain what it’ll bring, and there simply isn’t enough water to not conserve.

David Tucker is the communications manager for the Gallatin River Task Force.