Withlacoochee River System Update - 3/3/2025

Drier Than Average Winter Continues

 

Rainfall:

• Rainfall is the source of water to our region’s lakes, rivers, and aquifers…and yet it can be very unpredictable at times.
• Las month our region received around 1.1 inches of rainfall, well below the historical average for February (3.0 inches).
• Last year was a very wet winter, with 11.2 inches of rainfall from December through February.
• This winter has been much drier, with only 4.4 inches of rainfall over the past 3 months.
• Less rainfall is causing water levels and flows throughout our region to steadily decline.
• Aquifer (groundwater) levels remain above average, currently in the 66^th percentile for this time of year, higher than last year (55^th percentile).
• The figure below shows how much rainfall different areas received last month.

 

 

Withlacoochee River (from the Green Swamp downstream past Hwy 200):

• High water marks on trees and buildings bear witness to the severe flooding experienced last fall along the Withlacoochee River.
• But the river itself gives no indication of how high it was just a few months ago, as it peacefully meanders under normal conditions for this time of year.
• Along the entire Withlacoochee River, water levels and flows declined again during the month of February.
• This is a normal trend for our dry season, when rainfall totals average 2-3 inches per month.
• Last week, our area did receive some rainfall, which temporarily increased river levels and flows but it won’t have a lasting effect.
• River levels dropped an average of 6 inches last month, while flows declined another 21% in February.
• Many low-lying areas and wetlands throughout the watershed are still holding water, as evaporation and infiltration (downward seepage) are the only ways for these areas to drain.
• The table below compares current river levels and flows to what they were last month and last year.

 

 

Withlacoochee River in the Green Swamp (February 2025)

 

 

Tsala Apopka Chain of Lakes:

• All three pools of the Tsala Apopka Chain of Lakes continue to slowly decline as our dry season continues.
• In the winter months, when temperatures are cooler and trees/plants are dormant, the lakes drop very slowly.
• During the spring months, when it gets warmer and vegetation is drawing water to grow, water levels will drop quicker.
• In February, all three pools declined about 3-4 inches, which is normal for this time of year.
• The Floral City Pool is about 3 inches lower than it was a year ago, while the Inverness and Hernando Pools are currently 2 and 7 inches higher, respectively, than they were last year at this time.
• All the water control structures remain closed, helping to conserve water in the lake chain.
• Water levels in all the lakes/canals/wetlands that make up the Tsala Apopka Chain, are expected to continue to decline until the summer months bring excess rainfall to the area.

 

Wet Prairie near Flying Eagle Preserve (February 2025)

 

 

Lake Panasoffkee and Wysong:

• Across the river in Sumter County sits Lake Panasoffkee, a spring-fed lake with continuous inflows and outflow.
• Inflows to the lake from Shady Brook and Little Jones Creek declined slightly in February.
• Outflow from Lake Panasoffkee to the Withlacoochee River also declined last month.
• The water level on Lake Panasoffkee dropped during the first half of February but rose again last week due to rainfall over the lake.
• Overall, there was only a slight drop to lake levels from the start to the end of the month.
• Lake Panasoffkee is currently 10 inches lower than it was a year ago, mostly due to less rainfall this winter compared to last winter.
• The Wysong structure, located 3 miles downstream of Lake Panasoffkee, spans the entire Withlacoochee River.
• The main gate at Wysong (230-foot-wide) remains fully raised while the independent gate (19-foot-wide) is partially raised.
• Wysong is helping to maintain a higher level on Lake Panasoffkee while also passing river flows downstream.
• Both lake and river levels are expected to naturally decline over the next few months as the warmest dry season months approach.

 

Large Gator Napping along the Banks of the River (February 2025)

 

 

Lake Rousseau and the Lower Withlacoochee River (from Dunnellon to the Gulf of Mexico):

• Downstream of Dunnellon, the Withlacoochee River enters Lake Rousseau, an in-stream lake formed over a century ago with flood control structures near Inglis.
• Inflow to Lake Rousseau includes combined flows from the Withlacoochee and Rainbow Rivers.
• Rainbow River flow (which reflects changes in aquifer levels) fell 7% in February.
• Withlacoochee River flow (which depends on rainfall and runoff from adjacent lands) decreased 28% last month.
• Overall, inflows to Lake Rousseau have declined 19% over the past month but remain slightly higher than they were a year ago.
• Water levels on Lake Rousseau have stayed relatively constant the entire month of February.

 

• Flows that enter Lake Rousseau from the east exit through water control structures on the west end of the lake.
• The primary outlet from Lake Rousseau is the Inglis Bypass Spillway which provides continuous freshwater flow to the Lower Withlacoochee River.
• As inflows to the lake have declined, outflows have also declined, about 20% over the past month.
• The Inglis Bypass Spillway is currently flowing at 81% of its capacity.
• The Inglis Main Dam discharges excess water from Lake Rousseau to the Barge Canal, whenever the Bypass Spillway reaches maximum capacity.
• This structure, which had been open since early August, was finally fully closed in February when the Inglis Bypass was once again able to handle all incoming flows to Lake Rousseau
• Over the next few months, as inflows to Lake Rousseau are expected to continue to drop, less freshwater flow will be available to pass through to the Lower Withlacoochee.

 

 

Enjoy the beautiful weather!

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