Hydrologists are working to get a better picture of the Treasure and Payette valley aquifer, and how the water beneath our feet flows through the complex geological structure.
The U.S. Geological Survey is working with the Idaho Department of Water Resources to record water levels in about 600 wells in the area, triple the number that are regularly monitored. It’s the most widespread water level study in 25 years. Workers from local city water departments and water utility Veolia are also involved in the process, which is straightforward and quick.
"First thing we do is we sanitize the equipment to make sure we don't introduce any contaminants into the well," explained Kevin Olson, Idaho Department of Water Resources hydrogeologist.
We’re standing in the parking lot at the Eagle Bike Park, where, just off the asphalt, there’s what looks like an 8-inch metal pipe protruding about a foot and a half up from the ground. Its lid is hanging off along with an unlocked padlock as Olson prepares the measuring equipment.
"We're going to use this piece of equipment here called an e-tape, which is a basically a measuring tape that has a battery in it. And when this probe hits the water, it's going to go beep."
The reel squeaks as the tape goes further into the well, 50 feet, then 60, 70 feet and suddenly a loud beep.
"We see we have water here at 73.39 feet," Olson said.
And that’s it. The measurement is recorded and the process is done.
This unused, easily accessible well has an automatic measurement device inside; it's one of the about 200 Treasure Valley wells regularly monitored by IDWR. The manual measurement helps calibrate the automatic measuring tool.
This current effort to measure hundreds more wells is primarily meant to gather data from private wells and fill in areas of the map where data on the aquifer under our feet is sparse.
"We're going to have a lot of wells that were actually measured back in that 2001 study that we can compare to in this study and see what water level changes have occurred since then," said Ryan McCutcheon, IDWR hydrology project manager.
About 60% of wells officially measured 25 years ago will be measured again now. Many no longer exist, covered over by development as the local population has exploded. Others may be on property whose owners didn’t respond to the request to allow their well to be measured.
When asked why it has been 25 years since a study this broad was conducted, McCutcheon said it's a big undertaking.
"It's a lot of human resources and a lot of financial resources to pull something like this off."
Coordinating with different agencies and municipalities is a lot of moving parts, he said.
McCutcheon said updated data is needed for a new groundwater flow model being developed. The model is meant to improve understanding of the aquifer’s connections between the Mountain Home area and the greater Treasure Valley.
"This aquifer system is very complex. You have multiple layers of coarse sand and gravel that are interlaced with clays and mudstones that are confining layers," he explained. "What this is going to do is it's going to fill in data gaps and give us more information in between data points from our regular monitoring network."
Measurements will be conducted again in the spring and fall next year, providing three different snapshots in time for both long and short-term comparisons of water levels.
"Once we have all that data, we'll probably create some groundwater contour maps, some flow direction maps and determine really what has changed since that last mass measurement effort in 2001," McCutcheon said.
Measurements on varying timelines are important because water levels in some areas – especially shallow wells of around 200 feet or less – can swing with the irrigation season. Others, like the well at Eagle Bike Park, show a long-term trend of rising water levels. Olson says that’s a direct result of irrigation specifically near this well.
"There's a couple wells near here that are rising like this one. If you travel towards Eagle and Star it becomes more of a declining groundwater condition. Small declines, not large ones," he said. "Land use, the development over time, the way we're managing the recharge of the area could all contribute to different trends."
Results of the measurements will be posted to the department of water resources groundwater data portal as they’re collected, but will be analyzed as a whole in the coming months.
If you received a mailing about this well water measurement study coming to your property but haven’t responded yet, the Department of Water Resources still wants to hear from you. Follow instructions on the mailer, or call IDWR if you no longer have the information.
