SCRAPER, Okla. - David Overbey is no scientist, but he says a person doesn’t have to be to see how much the Illinois River has improved in recent years.

Overbey, a 67-year-old retired laborer who spends his days fishing the river in the foothills of the Ozarks in eastern Oklahoma, said the water is clearer now than it was 30 or 40 years ago, and the drum and channel catfish he catches are bigger. And other locals, too, say the river is slowly beginning to heal after decades of deterioration.

Some trace the roots of the recovery to 2005, when Oklahoma brought a pollution lawsuit against the Arkansas poultry industry, suggesting the threat of legal action may have spurred the companies to do better at policing themselves.

“The water quality is getting better, and this year, especially, we had very little algae,” said Archie “Trey” Peyton III, 35, a former environmental consultant who now runs the Peyton’s Place float company.

“There’s got to be a reason for that, which to me it follows that the last two years that most of the poultry litter in this region has been trucked out. But it looks to me like that’s making an impact on the river,” Peyton said.

But Oklahoma says the industry needs to do more, and its closely watched case against 11 companies - including food giants Tyson Foods Inc. and Cargill Inc. - goes to trial Thursday.

It’s been a long-standing practice among poultry farmers in the Illinois River watershed to spread their chickens’ droppings on their fields. But as big business took over the production of broilers, the amount of waste being spread on local fields ballooned - to an estimated 345,000 tons annually in recent years, according to Oklahoma.

Rather of disposing the waste in safer but more expensive ways - including burning it as energy, processing it into pellets or composting it - the state argues that Big Poultry has chosen the easiest, and cheapest, route. Runoff from the waste spread on the fields has polluted the Illinois River with harmful bacteria, degraded its water quality and caused algae blooms, the state argues.

The bacteria in the water threatens the health of the tens of thousands of people who use the river recreationally each year, and of the many businesses that rely on it.

The industry argues that Arkansas and Oklahoma sanctioned this practice by issuing farmers permits to spread the inexpensive waste.

The companies say they’ve also taken steps to reduce the amount of waste spread on the fields. Records provided to The Associated Press by the poultry industry show that nearly 290,000 tons of chicken waste have been trucked out of the area between 2005 through last month.

The four-year estimate, which does not include litter hauled away by the Oklahoma Conservation Commission, still is about 55,000 tons less than the amount of waste produced in just one year in the watershed.

But the industry says it’s a start, and says it’s spending millions of dollars researching alternative uses for chicken waste and has bankrolled various river improvement projects.

Other states considering taking on Big Poultry are closely watching the Oklahoma case, which is expected to last several weeks.

In the meantime, the poultry and tourism industries will continue to share the lush, 1 million-acre swath of land that extends from northeastern Oklahoma into western Arkansas, with its thick forests, babbling brooks and 1,800 low-slung chicken houses that dot the landscape.

Those who live and work along the river say its health appears to be improving. There’s the fatter and more plentiful fish, for one, and less of the thick algae that once coated the river’s bottom like shag carpeting. Local merchants say they logged banner seasons outfitting the tens of thousands of tourists who flock to the river each year.

“This river is better now than it was 20 years ago,” said Jack Spears, a retired college professor who owns Arrowhead Resort, the second-largest float company in the area. His operation equips roughly 20,000 customers a year for trips down the river.

Spears has spent most of his 75 years in this county and remembers when he could look at water so clear in the Illinois that 10 or 12 feet down seemed like 6 inches.

“If I was in (the poultry companies’) position, I’d say, ‘hey, let’s police our act. Let’s clean up our act, or they’ll be forced to by someone else,’” Spears said.

The other defendants named in the lawsuit are Cal-Maine Foods, Inc.; Tyson Poultry Inc., Tyson Chicken Inc., Cobb-Vantress Inc., Cargill Turkey Production L.L.C., George’s Inc., George’s Farms Inc., Peterson Farms Inc. and Simmons Foods Inc.

CAPE CANAVERAL, Fla. - Space shuttle Discovery is finally back home in Florida following a cross-country journey and a trip to orbit.

Discovery arrived at Kennedy Space Center at noon Monday atop a modified jumbo jet. The plane left Barksdale Air Force Base in Louisiana in the morning. The flight actually began Sunday at Edwards Air Force Base in California, where Discovery ended its space station visit.

Stormy weather prevented Discovery from returning to its home base 1 1/2 weeks ago. It ended up in California, the the backup landing site. The detour cost NASA nearly $2 million.

Discovery’s next flight is in the spring.

During the two-week mission, Discovery and its crew delivered a fresh load of supplies to the international space station.

ZURICH - Switzerland’s top technology institute says a U.S. chemist has resigned as head of research after scientific data were found to have been manipulated.

The Swiss Federal Institute of Technology, or ETH, says Peter Chen acknowledged responsibility as head of the research group that published the doctored data in 1999 and 2000.

ETH says it has not established who manipulated the data. It said Monday that Chen would remain at the Zurich-based institute.

Chen studied at the University of Chicago and completed his doctorate at Yale before moving to Harvard in 1988. He joined ETH - one of the world’s top research institutes - in 1994.

UNITED NATIONS - In the highest-level conference yet on climate change, 100 world leaders come to the United Nations on Tuesday to decide how to start an energy revolution.

While attention turns to U.S. President Barack Obama’s first U.N. speech, the most substantial changes may come from what the presidents of China, India and other major economies spell out for billions of people and their households, businesses and farms in the decades ahead.

Those leaders are expected to make more ambitious commitments than the U.S. leader, whose hands are still tied by Congress.

“We are asking developing countries to do as we say, not as we did,” said Ed Miliband, Britain’s climate secretary, whose nation has pledged to cut carbon emissions by more than a third from 1990 levels by 2020, and said 40 percent of the UK’s electricity by then would come from renewable sources.

Tuesday’s U.N. summit and the G-20 summit in Pittsburgh at the end of this week are intended to add pressure on the United States and other rich nations to commit to cuts and provide the billions of dollars needed to help developing nations stop cutting down their forests or burning coal.

China and the U.S. each account for about 20 percent of all the world’s greenhouse gas pollution created when coal, natural gas or oil are burned. The European Union is next, generating 14 percent, followed by Russia and India, which each account for 5 percent.

Chinese President Hu Jintao is expected to lay out new plans for extending China’s energy-saving programs and targets for reducing the “intensity” of its carbon pollution - carbon dioxide emission increases as related to economic growth.

China has been cutting energy intensity for the past four years and could the new carbon intensity goal in a five-year plan for development until 2015. China already has said it is seeking to use 15 percent of its energy from renewable sources by 2020.

India, too, may draw away some of the spotlight for laying out plans for the fifth-biggest contributor of global warming gases to bump up fuel efficiency, burn coal more cleanly, preserve forests and grow more organic crops.

The United States, under former President George W. Bush’s administration, long cited inaction by China and India as the reason for rejecting mandatory cuts in greenhouse gases.

Tuesday’s meeting is intended to rally momentum for crafting a new global climate pact at Copenhagen, Denmark, in December. Bush rejected the 1997 Kyoto Protocol for cutting global emissions of warming gases, which expires at the end of 2012, based on its impact on the U.S. economy and exclusion of major developing nations like China and India, both major polluters.

But neither China nor India say they will agree to binding greenhouse-gas cuts like those envisioned in a new climate pact to start in 2013. They question why they should, when not even the U.S. will agree to join rich nations in scaling back their pollution.

“The crisis today on climate change is the inability of the United States to put on the table credible emissions reduction targets for 2020,” said Jairam Ramesh, India’s environment minister.

The EU is urging other rich countries to match its pledge to cut emissions by 20 percent from 1990 levels by 2020, and has said it would cut up to 30 percent if other rich countries follow suit.

Japan’s incoming prime minister, whose nation generates more than 4 percent of the world’s greenhouse gases, has announced a new goal of a 25 percent cut in greenhouse gas emissions from 1990 levels by 2020.

Obama has announced a target of returning to 1990 levels of greenhouse emissions by 2020. Todd Stern, the top U.S. climate envoy, said the Obama administration is moving “full speed ahead” toward helping craft a global climate deal.

But with Congress moving slowly on a measure to curb emissions, the United States could soon find itself with little influence when 120 countries convene in Copenhagen.

The U.S. House of Representatives passed a climate bill this summer that would set the first mandatory limits on greenhouse gases. But action in the Senate has been delayed as lawmakers wrestle with overhauling the health care system.

China’s ambition to grow quickly but cleanly soon may vault it to “front-runner” status - far ahead of the United States - in taking on global warming, the U.N. climate chief said Monday.

“China and India have announced very ambitious national climate change plans. In the case of China, so ambitious that it could well become the front-runner in the fight to address climate change,” U.N. climate chief Yvo de Boer told The Associated Press. “The big question mark is the U.S.”