WASHINGTON — The government has incomplete data about lead in the country's drinking water, and that problem and others may be undermining public health, congressional investigators say.

A Government Accountability Office study released Thursday looked at implementation of the Environmental Protection Agency's 1991 Lead and Copper Rule.

The rule requires water systems to test tap water at certain high-risk locations. If elevated levels are found, the water systems must notify customers and in some cases take action to lessen corrosion.

According to EPA data, the number of water systems exceeding the lead action level dropped by nearly 75 percent over about a decade beginning in the early 1990s. But GAO investigators found that recent test results from over 30 percent of water systems were missing from EPA data, apparently because states were not reporting them.

Also, the EPA requires states to report certain "milestones" to indicate whether water systems' lead levels are acceptable, but this information was missing for more than 70 percent of water systems, the report said.

"EPA has been slow to take action on these data problems and, as a result, lacks the information it needs to evaluate how effectively the lead rule is being implemented and enforced nationwide," said the report.

This weakness and others _ including standards for plumbing fixtures that might not be protective enough _ "may be undermining the intended level of public health protection."

The EPA defended implementation of its lead rule.

"The Lead and Copper Rule has been effective in more than 96 percent of water systems serving 3,300 people or more, and we are committed to further strengthening protections from lead through additional actions," said Benjamin H. Grumbles, assistant administrator for water.

He said the agency will be proposing improvements to the rule in coming weeks. The EPA also announced in March plans for stricter lead level monitoring and reporting.

The report recommended changes, including improved data collection, lead monitoring requirements and standards for plumbing fittings.

The findings sparked criticism from Democratic Reps. John Dingell of Michigan and Hilda Solis of California and independent Sen. James Jeffords of Vermont, the lawmakers who requested the report.

"It is unacceptable that the Bush administration cannot account for the water quality of more than 33 million Californians, including our children," Solis said. "The status quo of allowing our children's health to be put at risk while failing to take action is beyond irresponsible."

Source: Associated Press