The magnitude of an unexpected rupture in the wall of the C&O Canal near Carderock became evident in August when a two-mile portion of the waterway was drained by the leak, leaving fish and marine life to die on the muddy bottom.

Although wall ruptures are common along the 157-year-old dirt canal, park rangers were surprised by the size of this hole, located between Locks 13 and 14, which was large enough for a small truck to pass through.

They had expected the repair work to take several weeks, but it has already taken more than a month: Workers discovered 14 smaller leaks in the canal's clay liner and decided to patch them, said David Murphy, chief ranger of the C&O Canal National Historical Park.

Murphy said that while work on the portion of the canal between Carderock and Great Falls probably of the canal between Carderock and Great Falls probably will not be completed for another month, maintenance workers have begun to fill it with about a foot of water. The canal is usually four feet deep.

"We'll have some water in the canal by this weekend," Murphy said. "But it will be low until we get the clay liner in place."

Richard Stanton, superintendent of the C&O National Historical Park, said the canal has developed many leaks since construction began on it in 1828.

"When it was being used as a freight-barging canal, they constantly had breaks that help up canal traffic for a week or two," he said. "It's a dirt canal. Not a concrete, masonry Army Corps of Engineers project."

In the last century, raw materials and produce were brought into Georgetown from Cumberland along the 184-mile canal. Today, the canal is run by the National Park Service and is used only for recreation.

Mother nature has dealt harshly with the fragile waterway. It has been partially rebuilt several times after floods and storms.

The canal wall was also damaged during flooding last year and by Hurricane Agnes in 1972.

The recent leak has destroyed hundreds of fish, mostly carp and catfish. After the water drained out of the canal, fish and other life died slowly in the muddy bottom. Some joggers and bikers have rescued some of the fish by tossing them into the Potomac River.

"The difficulty in doing that is that you wind up to your knees in mud," Murphy said.

Stanton said when workers show up for work in the morning they routinely collect the fish that are still alive and put them in the river.

"When we have a break like this it's a major disaster for us," he said. "There's nothing we can do about it."