In Seattle, an industrial firm found hiding toxic wastes in an underground pit is fined $1 million and its president sentenced to a year in prison.

In Winchester, N.H., a large leather company is convicted of dumping raw wastes into a nearby river, and the firm and five top officials are fined $498,000.

In Houston, a Chevron oil refinery is found allowing excess sulfur dioxide emissions into the air; the company is fined $4 million.

Three years after the scandal that gave the Reagan administration a reputation for cozying up to polluters, the Justice Department is quietly racking up impressive numbers in environmental prosecutions. The department's environmental crimes unit -- formed at the height of the controversy that shook the Environmental Protection Agency -- has produced 126 indictments and 109 convictions in the last three years, and another 59 indictments since Oct. 1.

Working closely with the FBI and a similar investigative unit at the EPA, the Justice Department has been increasingly successful in winning large fines against polluting companies and prison terms for some executives. There were almost no environmental prosecutions before the unit got under way in 1983.

"A lot of this activity has been going on for years, but it wasn't a crime because Congress didn't say it was a crime," said F. Henry Habicht II, assistant attorney general in charge of the Lands and Natural Resources Division. He said the more stringent laws and penalties have created a strong financial incentive for companies to cut corners.

To combat that, Habicht said, "The penalties should recover the economic benefit that someone gets by going for a couple of years without complying with the rules. They can save millions of dollars by going a couple of years without building the scrubbers or wastewater treatment equipment."

Justice officials say each prison sentence provides an important deterrent in a system that relies on voluntary compliance. "I don't think corporate America ever felt it ran the risk that officers may go to jail," said Judson W. Starr, head of the environmental unit.

As its enforcement staff has tripled, the division also has boosted the number of civil suits filed to more than 200 a year. These have produced consent decrees for $500 million in privately funded cleanups at hazardous waste sites.

Jim Moorman, who held Habicht's job in the Carter administration, said that creating an environmental crimes unit "was one that I was never able to accomplish. I think they've done pretty well."

The criminal units at both Justice and the EPA were created in the final months of Anne M. Burford's tenure as EPA administrator. Burford and her top aides resigned in March 1983 following disclosures of mismanagement and political favoritism in the Superfund cleanup program.

Richard Mays, the EPA's senior enforcement counsel, said Justice Department officials convinced Burford to go along with the units, but that investigations "were not a high priority at all" during her tenure. "That's why the enforcement numbers were so pitiful," he said.

Mays said that the EPA has gotten serious about enforcement under Burford's successors, William Ruckelshaus and Lee M. Thomas. While conceding that the 35-person unit is undermanned -- which sources say has limited the number of investigations it can take on -- Mays said it has referred a growing volume of cases to the Justice Department.

This effort broke new ground in December when the Justice Department brought the first criminal case that charges a defendant with knowingly placing others in imminent danger of serious injury. The case against Arthur J. Greer of Maitland, Fla., had languished for years with local prosecutors until the environmental unit got involved.

Greer was charged with criminally mishandling hazardous waste from 1980 to 1982 through four companies he owns. Greer caused employes "to become ill by having them sniff samples from drums of various wastes to determine the contents of the drums," the indictment said.

The employes suffered dizziness, breathing problems, headaches and eye irritation from exposure to such wastes as cyanide, toluene and methyl benzene, according to the indictment.

One worker's clothing was burned off when he handled a deteriorated drum of waste, the indictment said. In another case, it said, Greer had drums containing toxic waste from school laboratories labeled "nonhazardous" and "dirt."

Greer also was charged with cheating customers that hired his firms to transport hundreds of gallons of chemical waste, which he allegedly resold or dumped at an Orlando site without a federal permit. An attorney for Greer, who faces 17 years in prison and $300,000 in fines if convicted, could not be reached for comment.

Habicht's division is also expected to bring a spate of lawsuits to force the closure of hazardous waste disposal sites. More than two-thirds of the country's 1,600 such facilities have said they will close rather than comply with strict new EPA rules.

The owners cannot "just fold up their tents and leave" without cleaning up the sites, Habicht said. His office filed the first such civil suit this month, charging Conservation Chemical Co. of Illinois and operator Norman B. Hjersted with failing to submit a proper closure plan for a hazardous waste site in Gary, Ind.

The suit charges that some barrels at the Gary site -- containing such substances as cyanide, chromium, zinc, mercury and lead -- have leaked onto the ground, and it seeks $25,000 a day in fines until the site is properly closed. An attorney for the defendants declined comment.

Since these cases are highly technical, Justice and FBI investigators have joined in training courses with EPA experts. Such preparation paid off in a recent case involving a small laboratory hired by several Missouri communities to analyze their wastewater discharges for the EPA.

Investigators found that Eric D. Roth Sr. was reporting the same figures each month, with no seasonal adjustment, and charged him with making them up without doing any tests. Roth pled guilty to falsifying reports and received a four-month jail term.

Officials hope such convictions will spread the word that the federal cop is back on the environmental beat.

"The public still remembers the controversy and scandal that occurred," the EPA's Mays said. "We're still tainted with it. It's a lot harder to build back a good reputation than to tear it down, but I think we've done a lot to regain it."