Aug 24, 2016

Unwelcome Rains Will Put Stress on Lake Okeechobee’s Dike

Lake Okeechobee, Florida
USA
by
Jeff Masters
,
Weather Underground
Water level of Florida's Lake Okeechobee between January 2015 and August 23, 2016. Heavy winter El Niño rains forced emergency dumping in February, and dumping at a slower rate has continued all year. The Army Corps tries to keep the lake level below 15.5'; the dike surrounding the lake is in danger of failure when the lake level hits 18.5'. As of August 23, 2016, the lake level was 14.7’. Lake Okeechobee reached an elevation of 18.6' and 18.5'--both 1-in-30-year events--in 1995 and 1998. Image: USACE
Water level of Florida's Lake Okeechobee between January 2015 and August 23, 2016. Heavy winter El Niño rains forced emergency dumping in February, and dumping at a slower rate has continued all year. The Army Corps tries to keep the lake level below 15.5'; the dike surrounding the lake is in danger of failure when the lake level hits 18.5'. As of August 23, 2016, the lake level was 14.7’. Lake Okeechobee reached an elevation of 18.6' and 18.5'--both 1-in-30-year events--in 1995 and 1998. Image: USACE

Even if 99L never develops into a tropical cyclone, it has the potential to dump a large amount of rain on a place that doesn’t need it—the catchment basin of Lake Okeechobee in Central Florida. The huge lake represents an important source of fresh water to South Florida, but also poses a grave danger. The 25 - 30'-tall, 143-mile long Herbert Hoover Dike surrounding the lake was built in the 1930s out of gravel, rock, limestone, sand, and shell using old engineering methods. The dike is tall enough that it is very unlikely to be overtopped by a storm surge from the waters inside the lake, but the dike is vulnerable to leaking and failure when heavy rains bring high water levels to the lake. Torrential rains of 7+ inches from a tropical storm or hurricane are capable of raising the lake level by over three feet in a few weeks; this occurred in 2008, when Tropical Storm Fay took a leisurely romp across Florida, and again in 2012, when Tropical Storm Isaac lumbered past