(AP) -- Officials investigating the cause of a huge oil spill along a major river in southern Michigan say it will take months to clean up the mess, and damage to wetlands and wildlife may last considerably longer.
Enbridge Inc., the Canadian owner of the ruptured pipeline that released the crude into the Kalamazoo River, says the spill is contained. Gov. Jennifer Granholm said after a helicopter inspection of the stricken area Friday that the company's handling of the problem had improved since she gave it poor reviews earlier this week.
"I can say there's been significant progress," Granholm said at a news conference, adding: "I don't want to suggest we are satisfied. We continue to ask for additional resources."
Enbridge, based in Calgary, Alberta, said it was preparing to remove the damaged section of pipe as its focus shifted to cleaning up the spilled oil, which it estimates at 820,000 gallons. The Environmental Protection Agency puts the total at more than 1 million gallons.
"No one is sugarcoating it," company spokesman Alan Roth said. "There's still a tremendous amount of work to do, but good progress is being made."
EPA chief Lisa Jackson said she was "very confident" the oil would not reach Lake Michigan, where the river empties about 80 miles from where the spill has been contained.
Enbridge said it had recovered 100,800 gallons of oil and estimated that 420,000 gallons are in a holding area and will be pumped into tanks.
Federal and company officials said they were close to reaching the 40-foot section of pipe containing the break, which has been inaccessible because it's in a marshy, oil-covered area. Only when the pipe is reached will it be certain that the leak has stopped, said Ralph Dollhopf, EPA's on-scene coordinator.
Once removed, the section will be taken to a National Transportation Safety Board lab for tests, said Matt Nicholson, the agency's lead investigator. A team from NTSB's Office of Pipelines and Hazardous Materials division will be on site for up to 10 days, he said.
Scientists fear the worst may be yet to come for fish in the river. Jay Wesley, a biologist with the state of Michigan, said the oil spill had killed fish in "very limited numbers" along the affected stretch of the river from Marshall westward into Battle Creek.
The bigger problems for fish may come within a week or so, if the oil spill results in decreased water oxygen levels. Wesley said insects, algae, frogs and turtles along the river have been killed in high numbers - which could hurt the fish food supply.
"The effects are probably going to be more long-term," Wesley said. "We probably won't know the full effects for weeks or months or years."
The Marshall area has been considered a good area for bass fishing. Recreational anglers also fish the area for northern pike, catfish and suckers. Until the spill occurred, health officials considered fish taken from the waters from Marshall to Battle Creek OK to eat in limited amounts - unlike a downstream, westward stretch from Kalamazoo that is laden with PCBs and is on the federal Superfund list of highly contaminated areas.
Explore further: Montana oil spill estimate lowered to 30,000 gallons