HAMILTON, Mont. - Hydrogeologists want to study how land use changes are affecting water in the Hamilton area.
Ravalli County commissioners gave the Montana Bureau of Mines and Geology the OK to pursue how growth is affecting ground and surface water levels.
Hydrogeologists spent Wednesday afternoon on a section of the Bitterroot River calculating how much groundwater is coming into the river.
Ravalli County has seen a great deal of growth in the past few decades. The landscape is changing.
Bureau research hydrogeologist Todd Myse said scientists want to see how land use changes affect groundwater levels and surface water levels.
"We're also coming in here to look at nitrates," said Myse.
A source of nitrates is found in septic systems.
Commissioners gave the bureau permission to start the process of studying three sites on county land near Hamilton.
"We're looking at those three different sites," said Myse, "because they're located in three different aquifers."
Scientists want to see how quickly water moves through those aquifers.
"That would involve drilling some wells," said senior research hydrogeologist Ginette Abdo, "and pumping and monitoring the effects in nearby wells."
When they pump the water they want to know how much is groundwater and how much is surface water.
The hydrogeologists said irrigation water replenishes aquifers. Agricultural irrigation has been a major part of Hamilton's history. But many farms and ranches have been converted into subdivisions.
"There is some question what happens when you take that land out of production," said Abdo. "What would that do to our resources, to our water resources?"
Scientists said the information would provide a model to help make predictions on how ground and water are affected by land changes -- a kind of library.
"It would help water management people make informed decisions based on science," said Abdo.
She said they are trying to tell the valley's water resource story for future generations.
The Bureau of Mines and Geology scientists hope to have their report out in 2016.