BARATARIA PRESERVE - In the heyday of oil exploration on Louisiana's coast after World War II, companies dug about 10,000 miles of canals as straight as Kansas highways through a natural world that's unraveling today - due, in part, to those canals.

Soon, about 16.5 miles of canals are to be filled in the Barataria Preserve - making a small dent in a massive problem.

Interior Secretary Sally Jewell on Monday toured canals in the preserve by airboat. She called the work crucial.

The National Park Service is using $8.7 million from civil penalties drawn from the catastrophic BP Gulf of Mexico oil spill in 2010 to do the work.

Long ago, oil companies abandoned the canals and spoil banks, which have interfered with hydrology and funneled salt water inland ever since.