CORVALLIS - The state of Oregon has lifted a well-water warning it issued almost three years ago for homes in an area east of Corvallis.

The warning was issued in spring 2000 after a number of problems were found in fish at the Oregon State University Food Toxicology and Nutrition Laboratory. These problems included high mortality, altered growth, kidney damage and physical deformities.

The state had cautioned people who draw water from wells near the laboratory to consider using bottled water for drinking and cooking.

"There were no human health effects reported. We issued the warning solely on the basis of the fish problems," said Dave Stone, public health toxicologist for the Department of Human Services. "It was one of those situations where we wanted to use caution and let people know we were looking into this."

The warning was lifted Monday.

"We have completed an extensive sampling of the aquifer around the area and determined there was nothing of public health concern in the area," Stone said.

A report from the task force studying the problems said that no unusual events have been observed over the past 18 months.

The task force now believes that the fish deformities were the result of an "episodic event" and not an ongoing problem. The researchers ruled out several potential causes for the problems, including:

• A continuous source of contamination, such as a buried waste site.

• A biological agent bacterial or viral in nature.

• Toxic algae blooms from nearby surface ponds.

• Low levels of detected contaminants in well water.

Stone cautioned that even though the state is lifting the warning, well users should continue to use caution. "There's nothing to say it won't happen again," he said.

Shallow wells, typically wells that are 40 feet or less in depth, are especially susceptible to contamination, and should be monitored closely.

The fish laboratory is also helping to monitor the situation. The lab has installed new filters to protect the fish in its studies but will continue to leave some fish in tanks with untreated water.

"Those fish will kind of be our canary in a cage," Stone said.

Residents of the area with questions about their well water should call either the Benton County Extension Office at 766-6750 or the Linn County Extension Office at 967-3871.

A full report on the water study can be viewed online at www.dhs.state.or.us/publichealth/esc/docs/osulab.cfm.