Withlacoochee Update (Post-Milton) - 11/4/2024

Entire Withlacoochee River Has Crested; Water Levels Remain High

 

Withlacoochee River:

• It took more than three weeks, but the entire Withlacoochee River has finally crested, and most areas are now dropping.
• Flooding remains in many areas, and it will take weeks/months for some areas to return to normal.
• In the Green Swamp, river levels (which crested a few days after Milton) have now declined 5-6 feet and are dropping 2-3 inches per day.
• Near Trilby (US 301), river levels have already dropped 5 feet and are falling 4 inches a day.
• At Hwy 50, river levels have dropped nearly 3 feet and are falling 3 inches a day.
• Near Nobleton, river levels have dropped more than 2 feet in the past couple weeks and are falling 2.5 inches per day.
• At Hwy 48, river levels (which crested 12 days ago) have dropped about a foot and are declining an inch per day.
• Near Hwy 44, river levels (which crested last week) have only dropped about 2 inches so far and are declining around ¾ of an inch per day.
• Near Hwy 200, river levels finally crested last Friday, falling about an inch since then. They are currently declining ½ inch per day, but that rate will increase in the coming days.
• At Dunnellon, the river is currently cresting and should start slowly dropping this week.

 

Withlacoochee River Flooding near Hwy 44  (November 1^st, 2024)

 

 

 

Tsala Apopka Chain of Lakes:

• After Hurricane Milton, water was released from the lake chain prior to the river cresting.
• For the past 2 ½ weeks, floodwaters have been diverted from the Withlacoochee River back into the Tsala Apopka Chain of Lakes as the river was rising.
• River levels are now receding, and all three pools of the Tsala Apopka Lake Chain are near or above their high levels again.
• The Leslie Heifner structure was partially closed today but remains open moving some water off the river near Hwy 48.
• The Golf Course and Moccasin Slough structures are now closed preventing additional flow into the Inverness Pool which is above its high level.
• The Brogden Bridge structure (between Inverness and Hernando) was closed last week.
• Water levels in the Hernando Pool continue to rise because floodwaters from the Withlacoochee River are flowing overland through Potts Preserve into the Hernando Lakes.
• The Van Ness structure remains open, diverting maximum flow into Two-Mile Prairie.
• The S-353 structure remains closed, due to flooding near Hwy 200 and because river levels have nearly equalized with Hernando Pool levels.
• Staff will continue to adjust gate openings to benefit both the lakes and the river as they monitor the potential for additional rainfall this week.

 

High Water Levels near the Tsala Apopka Outfall Canal  (November 1^st, 2024)

 

 

 

Lake Panasoffkee and Wysong Structure:

• Lake Panasoffkee crested late last week and has dropped about 1.5 inches since Friday.
• Lake levels are currently dropping ½ inch per day as the Withlacoochee River slowly declines.
• Creek inflows into the lake from the east remain strong.
• Outflow from Lake Panasoffkee into the Withlacoochee River is the highest it’s been in decades, over 400 million gallons of water per day.
• The Wysong Structure on the Withlacoochee River, which was fully lowered in early August, remains fully lowered.
• River flows at Wysong remain very high as water levels slowly decline.

 

Aerial View of Wysong Structure – Fully Lowered  (November 1^st, 2024)

 

 

Lake Rousseau and the Lower Withlacoochee:

• The Withlacoochee River is currently cresting near Dunnellon, just below moderate flood stage.
• Flood levels would have been higher in this area if Lake Rousseau wasn’t drawn down over the past several weeks.
• The Inglis Main Dam on Lake Rousseau remains open several feet and the west end of the lake is 18 inches below its normal level.
• Over 3 billion gallons of water per day (~5000 cfs) is being discharged through the Inglis Main Dam to the Barge Canal, its highest flow in decades.
• Properties between the Dam and Barge Canal are experiencing “white water” conditions as these high flows exit to the Gulf of Mexico.
• Properties along the Lower Withlacoochee River were spared of flood damage from Hurricane Milton because of the Inglis Dam’s ability to divert these excess flows to the Barge Canal.
• The Inglis Bypass Spillway remains fully open, discharging maximum design flows to the Lower Withlacoochee River.
• As river levels recede near Dunnellon, Lake Rousseau will slowly return to its normal level.

 

Inglis Main Dam Discharging High Flows from Lake Rousseau (November 1^st, 2024)

 

 

 

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