A much anticipated, billion-dollar courtroom battle between Harris County and a group of companies over whether they bear responsibility for turning a site on the San Jacinto River into one of the most polluted places in the nation commenced in a packed courtroom Thursday.

Nearly half a century ago, the owners and operators of a paper mill dumped tons of dioxin-laced waste into pits on the banks of the river that over the years became submerged and started leaking the cancer-causing chemicals into the water.

Harris County and the state of Texas are now trying to hold International Paper Co., McGinnes Industrial Maintenance Corp., and Waste Management Inc. responsible for that pollution, claiming the companies intentionally abandoned the pits.

They want jurors, who heard opening arguments in the 295th State District Court, to determine that the companies should be fined the maximum allowed by state law - $25,000 a day going back to 1965, or about $1.6 billion.

The companies argue that holding them responsible under current law for actions taken by the previous owners is unfair.

The trial comes as federal regulators are considering the best long-term remedy for the site, which was designated a Superfund site by the Environmental Protection Agency in 2008. Any jury award of fines would be in addition to the amount the companies are required to pay to clean up the site under federal law.

No dioxin warning

In his opening arguments, Earnest Wotring, a lawyer representing the county, said the companies did not warn anyone about the dioxin in the sludge, did not stop it from getting into the river, and walked away from it for decades, even though they were warned they would be responsible for taking care of the pits.

Wotring said that back in the mid 1960s, the mill had waste product dumped by a contractor into three pits that with time were overtaken by the river, then released into its waters.

And Wotring contends companies involved knew very well that there was a problem and that one day they might be held responsible.

International Paper's lawyer, Winstol "Winn" Carter, said it was important for jurors to travel back to the 1960s to see how back then, the company did everything by the book and then some.

He said it wasn't even known that dioxin was part of the paper making process until the 1980s.

"Back then it was the Wild West with regard to disposal operations," he told jurors, noting that it would be years before so much more was known about the impact on the environment.

"Things have changed significantly over the years," said Carter, who showed jurors a photo of himself back in the mid-1960s as a fourth-grader, and noted that cars then did not have seat belts.

He said not only was the county advised of the mill's efforts to dispose of the sludge, but said it was doing things the right way.

The waste in the pits was produced by Champion Paper, which merged with International Paper in 2000. McGinnes, which is now defunct, owned and operated the pits and became part of Houston-based Waste Management in 2005.

Carter told jurors that International Paper quickly purchased Champion, to prevent it being bought by a foreign company, and was not then aware of its past involvement with the San Jacinto waste matter.

Memorandums, letters and other correspondence between business and government officials who are long gone are expected to take on a central role in the high stakes civil trial.

In the opening arguments, there appeared to be no dispute over whether the river was contaminated with the cancer-causing agents or if anyone had been harmed. The question was who should have known about the pollution, who should have done something about it and who should be responsible.

State District Judge Caroline E. Baker warned jurors that as they weigh whether any statutes had been violated, they should not be influenced by the fact that the EPA is overseeing a massive cleanup at the site.

The trial is expected to take weeks.

Packed courtroom

If jurors decide fines are warranted, the money would be split between Harris County and Texas, in addition to legal fees that are already estimated to be more than $10 million.

The courtroom was packed, with not even enough standing room for all those who wanted to observe the proceedings.

Among them were San Jacinto River area residents who say they've been harmed by the river's waters. Outside of the courtroom, a group of Vietnamese fishermen, who have filed a separate lawsuit against the companies claiming their livelihoods are affected by the pollution, stood outside the courtroom holding flags from the United States, Texas and South Vietnam.

As the trial got under way, among those with a front row seat was Jacquelyn Young, of the San Jacinto River Coalition.

Her father is among the people claiming to have been harmed by the dioxin.

Young said she was glad the case had made it to a courtroom where the facts could be aired publicly and evaluated by citizens.

"They have the opportunity to hold environmental polluters accountable," she said. "I want people to know the community is very concerned about this site and very engaged."