YAKIMA, Wash. -- An effort to address polluted groundwater consumed by many rural Lower Yakima Valley residents was formally launched Thursday as local, state and federal officials pledged to tackle a stubborn problem that's been decades in the making.

"It's going to be a big challenge. It's a difficult problem," said Tom Tebb, regional director for the state Department of Ecology in Yakima.

"But it matters because we have people drinking water contaminated by nitrate and bacteria and at unsafe levels in some cases," Tebb said at a news conference to announce the effort.

Five agencies released the final version of a report on groundwater quality that is a wide-ranging compilation of historical data about the contamination, health effects, regulatory responsibilities and recommendations for action.

The report has been in the works for more than year, starting with a meeting in Zillah in December 2008.

That meeting, attended by residents of the Lower Valley and by people who live near a dairy in Moxee, was prompted by a series of stories in the Yakima Herald-Republic in October 2008. The series, "Hidden Wells, Dirty Water," examined a long history of regulatory confusion and inaction on groundwater quality despite ample evidence of a problem.

Of some 30,000 private wells in the Lower Valley, 20 percent have elevated levels of nitrate and bacteria.

This week, federal regulators began their own testing program on 150 wells to try and determine the source of the nitrates and bacteria.

To make sure the samples are tested in a timely fashion, a mobile laboratory has been driven to Yakima from Manchester, Wash., on the Kitsap Peninsula, home of the regional lab for the U.S. Environmental Protection Agency.

Two microbiologists will test for coliform bacteria, fecal coliform and e. coli and conduct "microbial source tracking" to determine if the bacteria are human or ruminant. Cattle are ruminants, and manure from dairy and feedlots is one suspected source of both nitrate and bacterial contamination.

Another round of testing in April will help the agency determine the link between elevated levels of nitrate and sources of nitrate, which can come from manure, chemical fertilizer or septic systems.

If the test results allow regulators to identify obvious sources of pollution, enforcement action could follow, said Tom Eaton, director of the Washington operations office of the EPA in Seattle.

Results are expected sometime this summer.

In the meantime, Yakima County commissioners said they intend to apply to Ecology for certification of a Ground Water Management Area (GWMA) to address water quality issues.

"A GWMA is probably the best solution, in our opinion," said Commissioner Rand Elliott.

Groundwater management areas typically apply for government grants to operate.

Once funded, they conduct programs to require farmers and livestock producers to adopt new management practices, such as more closely regulating the application of manure to crops, a potential source of groundwater contamination.

Elliott said that while the state budget situation is bleak, he's hopeful a pending bill to fund water projects by Sen. Jim Honeyford, R-Sunnyside, will win support in Olympia.

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

For more information:

State Department of Ecology site on Lower Yakima Valley groundwater quality:

www.ecy.wa.gov/programs/wq/tmdl/yakima_wq/LowerYak-gw.html

Ecology Department Information for private well owners:

www.ecy.wa.gov/biblio/0611021.html

and in Spanish:

www.ecy.wa.gov/biblio/0611021sp.html