Oregon's Environmental Quality Commission Thursday adopted the strictest standard for toxic water pollution in the United States.

The new rules, adopted on a 4-1 vote, are designed to protect tribal members and others who eat large amounts of contaminated fish.

The changes, which drew thousands of public comments, dramatically tighten human health criteria for a more than 100 pollutants, including mercury, flame retardants, PCBs, dioxins, plasticizers and pesticides.

But improvements in water quality are expected to take years, if not decades, and it's not clear yet how much the rules will actually knock down pollution.

EQC Chairman Bill Blosser, a sustainability consultant and winery owner, called the new rules "a major first step" that put Oregon on the cutting edge of water quality regulation.

"But we've got a lot of work ahead to prove we can make this really work," he said after the vote.

The dissenting vote came from Jane O'Keeffe, a cattle rancher and former Lake County commissioner.

She said she shares concerns of farmers, ranchers, industries and others "operating on the front lines" that the new rule could end up costing millions while doing little to improve water quality.

"They gave a very compelling argument that this wasn't the time" for stricter rules, O'Keeffe said Thursday evening, "and that we could be putting money after something that may not achieve the goals."

Oregon's current water quality standard is built on an assumption that people eat about 17.5 grams of fish a day, about a cracker's worth. The new standard will boost that to 175 grams a day, just shy of an 8-ounce meal, to protect people who eat the most fish.

Those new consumption standards reduce allowable levels of 113 contaminants, which could boost costs for industries such as paper mills and for municipal sewage treatment plants, increasing sewer rates.

The tighter standards could also lower the health risks for those who eat a lot of local fish -- an estimated 100,000 Oregonians, including 20,000 children, according to a committee set up to consider the health effects of the new standard.

Industry, sewage treatment plants, farmers and foresters have all raised concerns about the changes.

But the Department of Environmental Quality, which will implement the standards, says waivers will be available for industry and treatment plants that can't meet them right away.

Those waivers, approved by the department's director and the U.S. Environmental Protection Agency, will include "pollution reduction plans" to ensure some progress is made, the agency says.

EPA has worked with Oregon during development of the new standards and says it supports the variance option.

DEQ has also assured farmers and foresters -- and concerned legislators -- that it will continue to allow the departments of agriculture and forestry to take the lead on enforcement of water quality violations for "non-point" pollution sources.

The concessions worry environmental groups, who say the new rules could end up being a paper exercise.

Blosser, the EQC chairman, said the new rules simply "reemphasized" that the agriculture and forestry departments have "the basic responsibility" to make the rules work, and that "if push comes to shove" the EQC can still mandate changes.

Oregon foresters have been able to show improvements in water quality under the state's forest practices act, he said, while agriculture has not yet demonstrated results.

Agriculture department officials say DEQ's increased work pinpointing the most polluted river basins will lead to more strategic pollution reduction, as farmers work with 45 soil and water conservation districts to cut erosion and runoff.

The department plans to boost water quality monitoring near farms and ranches to determine if the efforts are cutting pollution.

The new standards come nearly two decades after concerns about contamination in fish prompted studies that showed tribal members along the Columbia River eat far more fish than the general population.

Tribal leaders say they understand it will take time to meet the new standards, but add that they'll watchdog the variance process and regulation of non-point sources to ensure progress toward cleaner water.

The rules will take effect upon EPA approval, expected in the fall or early 2012.

-- Scott Learn