TAHLEQUAH, Okla. (AP) – It’s hard to picture the crystal-clear Illinois River that Oklahoma Attorney General Drew Edmondson remembers from his youth, how he could look to the bottom and spot a dime, no matter how deep the water.

That was almost 45 years ago, and time has not been a friend. Pristine water has turned to green soup in some places. Algae coats the rocks and pebbles that once seemed to sparkle when the light was just so.

The river’s watershed – where Edmondson saw his first daddy longlegs, floated away endless summer days and still comes to recharge – is the centerpiece of his federal lawsuit against the Arkansas poultry industry, which he says polluted the area with tons of bird waste from hundreds of poultry farms.

Two months before the Sept. 21 trial, he is driving through hundreds of acres of lush forest in his Ford Escape hybrid, taking the two-lane highways and narrow backroads he knows by heart.

His first stop: A public access area called No Head Hollow.

Edmondson gets out and rolls up the cuffs of his blue dress shirt. It may be the middle of summer, but the 62-year-old Democrat is in Oklahoma Politician Mode, sandwiching his drive between appearances for his gubernatorial campaign.

He walks down the river bank and takes in the scenery. A few beer cans litter the shore.

“This was our weekends,” he says, holding court among dragonflies and a chorus of locusts.

“Look! Over there!” Edmondson points to a creature darting into the tall grass. “I don’t know what that was. A muskrat?”

He remembers when the river started to change. It was in the early 1970s, after he got back from the Navy and a tour of duty in Vietnam.

“One of the things I noticed was the algae,” he says. In the lawsuit, Edmondson claims runoff from land that has been spread with chicken waste for decades has contaminated the watershed. He is suing a dozen Arkansas poultry companies that buy birds from the 1,800 poultry houses that dot the watershed in Oklahoma and Arkansas. The defendants include Tyson Foods Inc., the world’s largest meat producer.

Edmondson’s pedigree – the nephew of a governor, son of a congressman and brother of the chief justice of the state’s Supreme Court – has given Oklahoma’s case more weight, and it has drawn national attention because of the potential for similar environmental lawsuits in other states.

The next stop on Edmondson’s road trip is trickier to navigate, but worth the effort.

The attorney general squeezes his SUV under an aging, concrete bridge not meant for wide vehicles – a close enough shave to knock a few spiders onto his windshield – and drives halfway up a bluff overlooking the river. Nearby stands the house built for the 1974 film of the book, “Where the Red Fern Grows.”

“This river can right itself in a matter of years if we stop the runoff,” Edmondson says as he watches a pair of garfish swim near a cluster of rocks. A turtle pops its head above murky water.

If Edmondson can win a court order stopping the companies from disposing of large amounts of chicken waste on farmland, the lawsuit could have the broadest and longest-lasting impact of any he has worked on in his 15 years as Oklahoma’s attorney general.

But it will be tough to claim victory: A judge recently decided the state could not win damages because it failed to include the Cherokee Nation – whose lands lie within the watershed – as a plaintiff. The state had sought more than $611 million.

A second ruling barred two of the state’s expert witnesses, who were to testify about the pollution.

The stakes are high for Edmondson as well as the state. He’s running for governor in 2010.