TULSA, OKLA. — Opinions by one of the state's expert witnesses in a poultry-litter pollution trial are based on sound science and weren't developed by attorneys to fit the lawsuit, said Oklahoma Attorney General Drew Edmondson in a recent court filing. Mr. Edmondson refutes in a 109-page document filed May 26 in federal court a motion filed by 13 Arkansas poultry companies seeking to exclude the testimony of Valerie Harwood, according to The Associated Press.

Mr. Edmondson wants to use Ms. Harwood as a witness in Oklahoma's 2005 lawsuit against the poultry companies over allegedly polluting the 1 million-acre Illinois River watershed with poultry waste. She claims to have identified a poultry litter-specific "biomarker," and reportedly traced a path that contamination from poultry waste travels from fields into the watershed.

A trial is expected to begin in September.