BATTLE CREEK, Mich. — A Canadian company whose pipeline leaked hundreds of thousands of gallons of oil into a Michigan river boasts on its website of being “an industry leader in pipeline safety and integrity.”

A decade’s worth of leaks, an explosion and regulatory violations throughout the Great Lakes region and elsewhere in the U.S. suggest otherwise.

Embridge Inc. or its affiliates have been cited for 30 enforcement actions since 2002 by the Pipeline and Hazardous Materials Safety Administration — the U.S. Department of Transportation’s regulatory arm.

In a warning letter sent Jan. 21, the agency warned the company that it may have violated safety codes by improperly monitoring corrosion in the pipeline responsible for the massive spill Monday in Talmadge Creek, a waterway in Calhoun County’s Marshall Township that flows into the Kalamazoo River.

The Environmental Protection Agency estimated the spill at more than 1 million gallons of oil, and by Thursday, the slick had traveled at least 35 miles downstream. Gov. Jennifer Granholm warned of a “tragedy of historic proportions” should it travel another 80 miles and reach Lake Michigan and the vacation communities that depend on it.

Company spokeswoman Lorraine Grymala declined to comment Thursday about the Jan. 21 letter. After being criticized for dragging their feet in their initial response to the Monday spill, company officials have pushed the message that they’re doing all they can to clean and contain it.

On Thursday, hundreds of workers and contractors went to work on the oil with more than 12,000 feet of containment and absorption boom, 14 skimmers, 43 vacuum trucks and a number of tanker trucks, excavators and other trucks, Embridge said.

Health officials went door-to-door Thursday to advise residents in about 30 to 50 homes near the spill to evacuate because of air quality concerns, Calhoun County health official Jim Rutherford said. He said health officials were advising residents of about 100 homes near the river that use well water to use bottled water for drinking and cooking.

The slick, which emits a noxious, unpleasant odor, has killed fish and coated other wildlife in oil.

About 20 injured animals, mostly birds, were being treated Thursday at a wildlife rehabilitation center in Calhoun County’s Marshall Township, where the leak occurred, the U.S. Fish & Wildlife Service said. The center refused to admit an Associated Press reporter, and an agency spokeswoman said officials didn’t want to further traumatize the animals by allowing in more people.

According to the Jan. 21 warning, Enbridge was implementing an alternate way of monitoring corrosion in the pipeline, and had detailed to regulators the steps it was taking to track corrosion in the interim.

But the agency warned the company in the letter that it was violating code by not using a sufficient amount of certain chemicals used to protect pipe interiors, not using proper monitoring equipment to determine if those chemicals were working, and not examining its monitoring equipment at least twice a year.

“The transition from one technology to another must be implemented in a manner that ensures continued compliance with the regulations,” the agency wrote.

Two years ago, Enbridge was cited for committing eight probable violations that may have contributed to an explosion that killed two people working Nov. 28, 2007 on a 34-inch pipeline near Clearbrook, Minn. Among its findings, the regulatory agency found Enbridge failed to follow written procedures for couplings on the pipeline, didn’t make the repairs in a safe manner and didn’t make sure workers had adequate training for that job.

Jeff Share, editor of the Pipeline & Gas Journal, said violations like those Enbridge was cited for aren’t uncommon for pipeline companies.

“It is purely a pipeline company. If they’re not operated safely, they don’t make any money,” Share said. “It pays for them from a business and social perspective that their pipelines operate as efficiently and safely as possible.”

An Enbridge affiliate, Houston-based Enbridge Energy Co., spilled almost 19,000 gallons of crude oil onto Wisconsin’s Nemadji River in 2003. Another 189,000 gallons of oil spilled at the company’s terminal two miles from Lake Superior, though most was contained.

In 2007, two spills released about 200,000 gallons of crude in northern Wisconsin as Enbridge was expanding a 320-mile pipeline. The company also was accused of violating Wisconsin permits designed to protect water quality during work in and around wetlands, rivers and streams, the Wisconsin Department of Natural Resources said. The violations came during construction of a 321-mile, $2 billion oil pipeline across that state. Enbridge agreed to pay $1.1 million in 2009.

The Michigan leak came from a 30-inch pipeline, which was built in 1969 and carries about 8 million gallons of oil daily from Griffith, Ind., to Sarnia, Ontario.

Bruce Bullock, director of Maguire Energy Institute at Southern Methodist University’s Cox School of Business, said Enbridge is similar to many other pipeline companies. Noting the age of Michigan’s pipeline, Bullock said that like the rest of the industry, Calgary, Alberta-based Enbridge is dealing with aging infrastructure.

“They don’t have a reputation of being particularly a star player in terms of their profile or anything like that, but they certainly have a good reputation in terms of delivering for their shareholders,” Bullock said. “They certainly don’t have a bad reputation.”

But Andy Buchsbaum, director of the National Wildlife Federation’s Great Lakes office, said Enbridge has a history of spills — including two major leaks in the past year. He said those leaks, coupled with the fatal blast in Minnesota that killed two workers, are problematic.

“This is a company whose safety record is very definitely suspect and cause for concern,” Buchsbaum said.

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Runk reported from Detroit. Associated Press writers Corey Williams and Mike Householder in Detroit contributed to this report.