TOPPENISH, Wash. — Federal clean-water regulators will begin next week seeking permission from a number of well owners in Yakima County to test their water for contamination with the aim of identifying the sources of the problem and ultimately fixing it.

“We know there’s a problem. We’re beyond that,” Mike Cox, risk assessment supervisor at the Environmental Protection Agency’s Seattle office, told a group of about 50 stakeholders at an information session held at the offices of the Yakama Nation.

More than 12 percent of wells in the Lower Yakima Valley have tested above the maximum contaminant level of nitrates. In the Satus sub-basin, the figure is as high as 36 percent.

Although they welcomed the agency’s effort, several people in the audience were worried about the effect on families who find out their water is bad.

Excessive nitrates can harm infants and people with compromised immune systems. They can also indicate the presence of pathogens and chemicals like animal antibiotics, which can lead to human resistance to antibiotics.

“Do you realize this affects people very deeply?” asked David Bells, a pastor from White Swan.

Cox said the agency doesn’t have an easy answer except to supply owners with information on their options, such as bottled water or filtration systems. He said the agency doesn’t have money to help low-income well owners buy those filtration systems or drill a deeper well into cleaner water.

Officials at the Indian Health Service, however, indicated they have some resources for tribal well owners.

   The EPA effort, announced last fall, is the result of “Hidden Wells, Dirty Water,” a series published in October 2008 in the Yakima Herald-Republic showing that as many as 30,000 Lower Valley residents — most of them Latino farm workers — had been drinking well water contaminated by nitrates.

   Many rural residents in unincorporated areas depend on private wells for drinking water. The wells may be old, poorly constructed, leaky and close to irrigation drainage systems, dairies or feedlots.

Using a geographic information system, EPA is identifying wells for testing that are likely to be high in coliform bacteria and nitrates, contaminants that come from nitrogen-rich fertilizer applied to crops, dairy manure, feedlot runoff and human waste from leaking septic systems.

The agency wants to identify 550 wells and has set a goal of getting at least 150 residents to permit the sampling, which is scheduled between February 22 and March 7. The aim is to collect the samples before the start of the irrigation season on April 1.

Once it has the samples, the EPA will use various scientific techniques to identify the sources of the pollutants.

“Whose coliform is it? We’ll be looking at an amazing array of things,” said Curt Black, an environmental scientist with EPA. A mobile laboratory will be able to detect pesticides, hormones, antibiotics and personal-care products, such as prescription drugs.

After the results are published this summer, the agency will consider steps to address the problem, ranging from enforcement actions that would target polluters with legal action to requiring new “best practices” in the application of fertilizer and storage of manure.

The EPA’s Cox noted that the study has some limitations.

For example, the sampling is not the same as groundwater monitoring that would allow for a more complete picture of water quality over time. It will also be difficult to determine if the contaminants are old or new, which would indicate if the problem is historic or current.

Phil Rigdon, deputy director of the Yakama Nation’s Natural Resources Department, thanked EPA for the effort but wondered whether it will lead to any change.

“How do we get rid of the dirty wells? That question is still out there. How are you going to fix it so our community is safe?” Rigdon asked.

Said Black: “We’ve got to do something that changes what’s happening.”

Leah Beth Ward can be reached at 509-577-7626 or lward@yakimaherald.com