It’s been more than two months since Hurricane Irma cut a path through the heart of Florida, bringing damaging winds and relentless rains to many of our communities. Coming off a dry and dangerous wildfire season earlier in 2017, the summer rains were a welcome relief to some. But when Hurricane Irma hit an already saturated region, many residents living along the 160-mile Withlacoochee River worried about their safety and property.
The winding Withlacoochee River flows northward through eight counties from its source in the Green Swamp before it empties into the Gulf of Mexico near Yankeetown. During the storm, many residents watched and waited for news about when the river might swell and crest in their neighborhoods.
The Southwest Florida Water Management District worked diligently before, during and after the storm to carefully estimate potential flooding along the Withlacoochee River. It’s extremely difficult, however, to predict the exact height to which the water would rise and when it would crest. Experts from the National Weather Service also provided information at several locations along the river for local governments and residents to monitor the predicted flooding.
Before the storm, the district opened the Inglis Dam, allowing water to drain and to create additional storage in Lake Rousseau due to the predicted storm surge near Yankeetown. The Wysong-Coogler Water Conservation Structure, near Lake Panasoffkee, was fully lowered to minimize flood risk upstream of that structure.
More than 10 inches of rain fell on nearly the entire watershed overnight, causing river levels to crest in the Green Swamp (at the beginning of the river) on Sept. 15. Over the next few weeks, the flood wave passed the entire length of the river, with communities in Polk, Pasco, Hernando and southern Sumter counties experiencing the highest water levels they have seen since 1960. Further downriver, communities in Citrus, Marion and northern Sumter counties were slightly more fortunate, with flooding a bit less severe than the 2004 hurricane season.
During and after the hurricane, and with the expertise of the district’s engineering and watershed management personnel, district scientists worked tirelessly to document the peak of the flooding by capturing high-water marks with photos to better identify flood-prone areas and worked with local governments on flooding solutions. After the hurricane, the district created storage in Lake Rousseau to assist with flooding near the Dunnellon area.
District staff also worked in collaboration with the Florida Fish and Wildlife Conservation Commission to monitor a significant fish kill along the river and in Lake Panasoffkee. For weeks, this natural flood effect brought decaying plant matter into the river, depleting the oxygen levels in the water. Fortunately, this was only temporary and the river ultimately recovered.
Throughout this entire weather event, district experts were in constant communication with the community, partnering with local governments to inform residents of what was expected so they could plan to protect themselves and their families. However, the work isn’t finished. Information collected during the storm will be used to support the district’s High-Water Database and Watershed Management Program, which assist local governments, floodplain modelers and residents in better understanding flood risk and help in the development of solutions to flooding problems where possible. Working together with local governments and residents, the district will use this year’s experience to be even more prepared for next year’s storm season.
Mark Fulkerson is a senior professional engineer with the Southwest Florida Water Management District.