A report on water quality throughout the Wood River Valley, released by the U.S. Geological Survey on Friday, indicates that decades of development have had little impact on the purity of drinking water.
The report was the last step in a four-phase study initiated in 2006 and funded half by the USGS and half by all the local municipalities and by The Nature Conservancy.
A report on Phase I of the study, released in January 2008, analyzed water-quantity trends.
The study’s water-quality phase, which cost $144,000, analyzed 45 wells and five surface-water sites on the Big Wood River in July and early August 2012. The sampling sites were spread from the Sawtooth National Recreation Area headquarters north of Ketchum south to U.S. Highway 20, including throughout the Bellevue Triangle.
“The concern was that growth in the Wood River Valley could lead to groundwater contamination.”
Blaine County commissioner
“The concern was that growth in the Wood River Valley could lead to groundwater contamination,” Blaine County Commissioner Larry Schoen said. “This study seems to reinforce earlier results that we don’t have serious contamination or widespread contamination.”
The report found levels of nitrate and nitrite, both of which can be produced by human activity, to be within U.S. Environmental Protection Agency standards. Both nutrients can have harmful effects on human health, especially that of infants.
The study found that nitrate and nitrite concentrations varied, but were higher near population centers and in agricultural areas than in Big Wood tributaries and less populated areas.
“Overall, the water quality in the valley is very good,” said the report’s author, USGS hydrologist Candice Hopkins, in an interview.
Hopkins said that given the Wood River Valley’s geology, little contamination was expected from natural sources in the underlying rocks and sediments. She pointed to arsenic as an example of a natural contaminant that can be produced by some kinds of volcanic rocks.
The report states that E. coli bacteria, which are usually associated with fecal material, either from humans, domestic animals or wild animals, was found in all five surface-water sites and in two wells. Hopkins said the tests were as a means of using the bacteria to determine the sources of any nutrients found, and were not conducted in a way that can be correlated with EPA standards. She added that stream waters are not considered to be potable.
“It’s not a contaminant issue so much as something that naturally occurs,” she said. “You would expect to see coliform bacteria in any natural source.”
Schoen said the cooperative funding for the studies “demonstrates the ability of many different interest groups to come together and do serious research.”
He said he hopes the report will help prompt voters in Hailey to support a bond issue to pay for a new wastewater treatment plant on the ballot this November.
“Maintaining high water quality is very important for everybody who lives in the Wood River Valley,” he said.
Greg Moore: firstname.lastname@example.org