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Mark Kerns, with Avion Water Co., Inc., said declines in groundwater levels shouldn’t be a problem for cities or large users, whose wells reach deeper underground.
Pete Erickson / The Bulletin
Drop in groundwater perplexes scientists
By Nick Budnick / The Bulletin
Published: February 23. 2009 10:52AM PSTSALEM — State and federal scientists are investigating a mysterious drop in groundwater levels in the triangle between Redmond, Prineville and Powell Butte.
One mile south of Redmond, for instance, they’ve seen water levels underground decline nearly 20 feet in the last 15 years.
If that trend looks to continue, it would be “troubling,” said Doug Woodcock, a Salem-based groundwater manager with the Oregon Water Resources Department.
And depending on where the new study points the finger, he acknowledged, it could reignite debate over a touchy subject: how water is managed in the Deschutes area.
“Basically, what we’re trying to get a read on is, how solid (is) our management in this basin?” he said.
To let developers build and farmers grow, the state’s Deschutes groundwater mitigation program requires users to purchase water rights to offset the effect their activities might have on the Deschutes River and its tributaries.
However, if the new study suggests that the program is not protecting underground water supplies, then it could lead to tighter rules, according to Kimberley Priestley of the group Water Watch of Oregon.
“I would think it would be of interest not only to the state but to developers,” she said of the study. “If we’re seeing declines, then that could bring a whole new layer of management.”
A July 2008 U.S. Geological Survey document said that some of the area’s well-water declines are because the basin started receiving less rain in the 1950s. However, it added, many wells “in the more developed parts of the basin appear to show declines larger than what would be expected due to climate alone.”
If that is true, then it could have “important implications” for the Deschutes groundwater mitigation program, the document said.
A new model
For months, state officials been working with USGS hydrologists on the new study. They have been gathering data to dust off a computer groundwater model they haven’t updated in years.
The three-dimensional model essentially carves the basin’s surface area into hundreds of tiny squares, then cuts each of them into eight layers extending 1,800 feet deep. Each section is assigned a value to show how easily water moves through it, to simulate how water moves through the region’s underground layers of rock, sand and sediment.
The model is being updated to show the number and location of new wells, add more recent data on rain and snowfall, and to show that some irrigation canals have been replaced by pipes – affecting recharge of the underground aquifier.
Once that work is complete, hydrologists will run tests to determine how much of the reduced groundwater reduction is due to pumping, how much to irrigation changes, and how much is attributable to reduced rain and snowfall.
Different opinions
It’s a study that Kevin Limbeck will be watching with more than casual interest.
Limbeck is board president of the Powell Butte View Estates Water District, which serves 88 homes perched on the butte’s western slope. He says the district drilled its well more than a decade ago, and has seen its water level drop 15-20 feet.
While it isn’t affecting them now, he said, “In five or 10 years, who knows?”
He contacted the state water department about the issue, and was told that officials are working on it already.
Limbeck is keeping an open mind, but suspects the rapid pace of development in recent years is largely to blame, saying, “There’ve been quite a few large wells put down in the Powell Butte area.”
Limbeck thinks Brasada Ranch is one possible contributor to the problem. But Mark Kerns, an Avian Water Co. manager who helps supply water for the development, disagrees. He said the development has barely started to pump due to the slow economy.
He agrees that pumping for new homes around Redmond, as well as changes in irrigation, such as moving water in pipes rather than canals, could be to blame for the decline in government observation wells. But he said the declines in upper reaches of groundwater don’t pose a problem for cities and large users, whose wells reach deeper underground.
“All the wells we trust up there are in the 600-foot range,” he said.
Marshall Gannett, the USGS hydrologist who is spearheading the study, said he doesn’t think the declines pose an “imminent risk” to the basin’s underground resource.
The study is expected to be completed by year’s end.
Nick Budnick can be reached at 503-566-2839 or at nbudnick@bendbulletin.com.
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