Withlacoochee Update (Post-Milton) - 10/21/2024

Withlacoochee River Still Rising in Some Areas

 

Note: In the update below, I’ve included links to the USGS gauge conditions so you can keep an eye on what the river is doing in different areas.

 

River Crest Timing:

• The Withlacoochee River has now crested from the Green Swamp to Nobleton.
• Areas downstream (north) of Hwy 48 are still rising.
• The National Weather Service has updated their timing forecast for when the Withlacoochee River may crest in the remaining areas.
• If you live near an area that has already crested it doesn’t mean that water levels in your area have reached their highest level yet.
• As a river rises out of its banks, it pushes laterally to flood adjacent lands, so many areas farther from the river may still be rising as those floodwaters seek to level out, even though the river has crested nearby.
• After river levels crest, it may we weeks/months before those floodwaters totally recede.

 

 

 

Little Withlacoochee River (Sumter/Hernando Counties):

• The Little Withlacoochee River at US 301 has been slowly dropping for the past 6 days, but remains in flood stage.
• Properties downstream (west) of US 301 should have now crested and will see water levels decline in the coming days/weeks.

 

 

Withlacoochee River (Green Swamp to the Gulf of Mexico):

Green Swamp

• The Withlacoochee River at SR471, in the middle of Green Swamp, crested on October 12^th and has dropped 2.5 feet since then.
• At the Dade City gauge on the west side of the Green Swamp, river levels crested on October 13^th and have fallen nearly 2 feet since then.
• Many homes near Dade City are still seeing rising water levels as floodwaters from the Green Swamp continue to push out laterally from the river and fill up low-lying lands.
• There are no water control structures in the Green Swamp that could hold back or divert any floodwaters.

 

Trilby and Ridge Manor

• The Withlacoochee River crested at Trilby (US301) on Friday night (Oct 18^th) at its highest level in 110 years (since 1934).
• The National Weather Service is predicting Trilby to continue to slowly recede in the coming days/weeks.
• The river at Trilby rose 10.5 feet from Hurricane Milton.
• After rising 9 feet in 9 days, the river near Ridge Manor (SR50) crested on Saturday (Oct 19^th).
• River levels in Ridge Manor remain very high and it will take weeks for the flooding to recede.
• Properties away from the river near Trilby and Ridge Manor may still see water levels rise for a couple days as the floodwaters level out into adjacent low-lying lands.

 

Nobleton and Hwy 48

• Downstream at Nobleton (CR476), the Withlacoochee River finally began cresting yesterday (Oct 20^th).
• River levels at Nobleton rose 5 feet from Hurricane Milton and will remain high for many days/weeks.
• At Hwy 48 (between Floral City and Bushnell), river levels appear to be cresting today, after rising 3.5 feet from Milton.
• Just downstream of Hwy 48 near Trails End in Floral City, water levels are still slowly rising but expected to crest in the next day or two.
• The Leslie Heifner structure at Trails End remains open, bringing river water into the Tsala Apopka Chain of Lakes.

 

Hwy 44 and Hwy 200

• River levels at Hwy 44 are rising more rapidly now and are currently about 6 inches higher than the peak from Hurricane Irma (2017).
• The increased rate of rise is due to areas upstream that have finally peaked and higher flows making their way downstream.
• The Withlacoochee River at Hwy 44 is expected to rise for another 4-6 days possibly peaking a foot higher than it is today.
• At Hwy 200 (Holder), the Withlacoochee River is also still rising and will continue to rise for another 10 days or so.
• The National Weather Service is predicting Hwy 200 will rise about 12 inches by the end of this week, and could rise 1.5 to 2 feet higher from now to the end of October.
• The S-353 structure was closed today as river levels continue to rise near Hwy 200, farther upstream we are diverting some of the floodwaters into the lake chain.

 

Dunnellon and Lake Rousseau

• Over the past few days, the Withlacoochee River at Dunnellon (Hwy 41) has also begun to rise more rapidly due to increased river flows making their way downstream.
• The river at Dunnellon, which is now in minor flood stage and rising, is expected to crest by early November, possibly a foot higher than it is now.
• Lake Rousseau remains lowered as the Inglis Dam, which was opened on August 3^rd, continues to discharge high flows to the Barge Canal.
• The lake may continue to drop as increased flows are discharged to help prevent greater flooding at Dunnellon.
• The Inglis Dam has no effect on river levels upstream near Hwy 200 or other places farther upstream.

 

Lower Withlacoochee River

• The Inglis Bypass Spillway is fully open, discharging high flows to the Lower Withlacoochee River.
• The Inglis Dam is also open discharging increased river flows into the Barge Canal.
• Residents living between the Inglis Dam and the Barge Canal should expect increased flows and higher river levels in the coming days.

 

 

Tsala Apopka Chain of Lakes (Citrus County):

• The Tsala Apopka Chain of Lakes are being used to divert water off the Withlacoochee River.
• The Leslie Heifner structure on Trails End Rd remains open, moving high flows of water into the lakes from the flooded river.
• The S-353 structure in Hernando is now closed and no water is flowing from the lakes into the Withlacoochee River.
• The Hernando Pool may rise a few inches over the next week as we fill it back up to its high level.
• The Floral City and Inverness Pools should stay about the same levels as we move river water through the system.
• The Van Ness Structure remains open, discharging flows from the Hernando Pool to Two-Mile Prairie.
• Even with these structures open, there is no way to prevent the flooding we are experiencing on the Withlacoochee River.

 

 

Lake Panasoffkee and Wysong Structure (Sumter County):

• Lake Panasoffkee is rising quicker now.
• As of this morning, the Withlacoochee River has risen above the level of the lake.
• High flows are still entering Lake Pan from the east and now the river is starting to flow into the lake from the west.
• The Wysong Structure on the Withlacoochee River, which was fully lowered in early August, remains fully lowered.
• The boat lock is also fully lowered, discharging as much flow as possible downstream.
• With nowhere to drain, Lake Panasoffkee may rise another foot over the 5-7 days.
• Lake levels are currently 8 inches below their peak from the 2004 hurricanes.
• There is no way to lower the rising water on Lake Panasoffkee. It will start dropping once the river crests nearby and begins to fall.

 

Best Regards,

Mark

 

 

 

 

Mark Fulkerson, Ph.D., P.E.

Chief Professional Engineer

Southwest Florida Water Management District

 (352) 269-6073 (office)

(352) 279-4493 (cell)

Mark.Fulkerson@WaterMatters.org

 Withlacoochee River Watershed Initiative