By Kristin Gardner EBS CONTRIBUTOR
Groundwater
quality and quantity is threatened by the proliferation of septic systems and
individual wells in the Upper Gallatin Canyon potentially leading to
degradation of drinking water supplies and the health of the Gallatin River. To
better understand these impacts, the Montana Bureau of Mines and Geology is
conducting an extensive study over the next three years.
“This study
will answer many important questions about the underlying aquifer including
recharge sources, nutrient loads and connection to the Gallatin River,” said
Mike Richter, a long-time Big Sky resident and research specialist for the
MBMG. “The shallow aquifer is of most concern because it is utilized by
residences, businesses and our local school system.”
MBMG
Groundwater Investigation Program, which is funded through the Montana
legislature, will oversee the Upper Gallatin Canyon study. This program
supports science-based water management in Montana and “is important for the state
because it provides stakeholders with answers to locally identified, site
specific questions,” said Ginette Adbo, the manager for the GWIP program.
To qualify
for a GWIP study, a project must be nominated by a local entity. The Gallatin
River Task Force in partnership with the Gallatin Local Water Quality District
submitted a nomination for the Upper Gallatin Canyon project in spring 2018.
The need was identified as a priority action item outlined in the Big Sky
Sustainable Watershed Stewardship Plan, produced in 2018 through a
collaborative local planning effort.
The Upper
Gallatin project was one of three GWIP projects selected across the state to
start in 2019.
Assessing
groundwater flow and transport of contaminants is complex and there is a
certain mysteriousness because you cannot see what is below the surface.
Groundwater flow is slower than river flow but this movement ultimately affects
how and where land uses impact the river.
The study
will also assess when and where groundwater interacts with the Gallatin River.
This
interaction may vary in location and across seasons. In some situations or
locations, the river may gain water and pollutants from the groundwater system,
while in other situations, the river may recharge groundwater and cause changes
in groundwater quality.
To get at
these questions, MBMG anticipates measuring groundwater levels and water
quality in 35-40 wells and will test surface water quality and flow at 11
locations across the study area.
“We also
anticipate drilling some wells in the area next summer, if necessary, to
determine the thickness of the alluvial aquifer, the nature of the underlying
bedrock and water chemistry,” said James Rose, associate hydrogeologist for
MBMG.
“The
knowledge gained will be integral to fully understand Big Sky’s water resources
and make wise, informed decisions regarding land, water and wastewater
management in the Upper Gallatin Canyon,” Richter said.
To learn
more about the upcoming Gallatin Canyon GWIP study, attend the public kickoff
meeting on Dec. 11 from 4-6 p.m. at the Big Sky Water and Sewer District.
Kristin Gardner is the executive director of the Gallatin River Task Force .