Natural healing, coupled with restocking of fish by state biologists, has allowed anglers to return to the banks of the stream on the Kentucky-West Virginia border.

"Fishermen have been catching high numbers of small fish," said Kevin Frey, a state biologist. "That would suggest that the river is beginning to heal."

The spill, one of the South's worst ecological disasters, affected the main stem of the Big Sandy, the Tug Fork and some of its tributaries, including Coldwater and Wolf creeks in rural Martin County. Frey estimated that 1.6 million fish smothered in the molasses-like substance.

The sludge broke through the bottom of a mountaintop impoundment on Oct. 11, 2000, gushing through underground coal mine portals before flowing into the streams.

Lawns were buried up to 7 feet deep in sludge. Biologists said every fish in Coldwater and Wolf creeks was killed, and many in the Big Sandy River died.

Massey Energy, which owned the 72-acre impoundment that ruptured, reported spending $46 million to clean up the spill. The company also paid $3.25 million in penalties and damages to the state of Kentucky.

The company also agreed to pay a $225,000 fine levied by the Kentucky Department of Fish and Wildlife Resources.

Frey said the state began using that money to restock fish last year. He said the restocking is expected to be complete by 2006, when West Virginia releases the last hatches of sauger and walleye into the stream.

As of last week, the state had released 22,860 flathead catfish, 22,500 channel catfish, 30,000 bluegill and 525 largemouth bass.

Fish have also migrated into the tributaries and the main stream from unaffected areas.

David Morgan, director of the Kentucky Division of Water, said all of the affected streams have recovered well. "They're back to at least the condition they were in before the spill," he said. "They're still not pristine streams. Things are looking much better than they were."

Frey said surveys of fishermen suggests that the Tug Fork has nearly as many fish now as it did before the spill. The fish, however, are younger and not as large. He said Coldwater and Wolf creeks also have rebounded well, thanks in large part to numerous floods that have occurred over the four-year period.