for National Geographic News
About 2,500 people died in 1928 when water from Florida's Lake Okeechobee inundated their communities during a hurricane, making it one of the worst natural disasters in United States history.
Today the earthen barrier of Herbert Hoover Dike140 miles (225 kilometers) long, 35 to 50 feet (10 to 15 meters) highstands between area residents and the nearly Rhode Island-size lake.
Hurricanes have crossed or passed near the lake since the 1928 disaster. None of the storms has penetrated the massive dike or pushed water over its top. (See an interactive feature on hurricanes.)
But the dike has begun to leak.
The U.S. Army Corps of Engineers first noticed the problem when inspectors found evidence of "seepages" in the 1980s, according to Jacob Davis, a civilian engineer in charge of repairs.
The leaks are caused by water under constant pressure pushing against the dike, loosening soil, and gradually seeping through. As the water level rises, it exerts more pressure on the dike, and the seepage can worsen and cause the dike to fail.
"Water flows through the ground naturally," Davis said. "At every dam site around the world, seepage occurs. The water tends to move through gravel or clay and sand."
As the water moves, it finds larger openings and follows the paths of least resistance, Davis said.
Engineers are currently repairing a 22-mile (35-kilometer) section of the dike on the lake's eastern shorepart of a years-long effort to restore the dike.
About 40,000 people now live in lakeside towns such as Okeechobee, Pahokee, Belle Glade, and South Bay.
The dike, always looming somewhere in the background, has become part of life by the lake. But residents haven't forgotten the long-ago catastrophe.
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