KANSAS CITY, KAN. ? The president of a southeast Kansas water-testing laboratory has pleaded guilty to a charge of falsifying lab results, federal officials said.

As part of an agreement with prosecutors, Terian Koester, president of Quality Water Analysis Laboratories Inc. of Pittsburg, recently pleaded guilty to one count of making a false statement under the federal Clean Water Act by falsifying analytical results of wastewater, and one count of mail fraud.

He is scheduled to be sentenced Sept. 16 by U.S. District Judge G. Thomas Van Bebber in Kansas City, Kan.

Authorities shut down QWAL in September 2001 after an investigation by the Environmental Protection Agency alleged the lab had falsified during a five-year period records used to determine the safety of wastewater and treated hazardous wastes dumped into Kansas streams and rivers.

The EPA sent letters to nearly 900 clients of the lab, urging them to have their samples re-tested.

Federal and state authorities said Koester signed statements admitting to having falsified data.

Ray Bosch, an EPA attorney, said Koester has cooperated with authorities. The investigation into the lab continues, he said.

Bosch said other incidents of falsified records, aside from the one specifically charged against Koester, could be taken into account when Koester was sentenced.

Shari Stammer, water quality manager for the city of Lawrence, said the city had some testing done by QWAL. But Stammer said she has been assured by federal and state authorities that those specific kinds of tests were not the kind that were falsified.