Withlacoochee River System Update - 5/1/2020

April Showers Bring May Flowers…and Some Relief to our Declining Water Resources

  

Rainfall:

• Last month our region received an average of 4.6 inches of rainfall; much higher than the historical average (2.7 inches) for April.
• That’s more rainfall than the previous three months combined and a welcome relief after essentially no rain in March.
• The sharp decline our water levels and river flows were experiencing has come to a stop, at least temporarily.
• Aquifer levels have continued to steadily decline (which is normal for the dry season) and are now in the 59^th percentile for this time of year.
• Overall, our rainfall deficit for 2020 (actual rainfall received minus historical average rainfall) shrunk from -6.3 inches to -4.4 inches after a wet April.
• Unless we receive above average rainfall in May, we can expect water levels and flows to continue to decline until our wet season officially begins this summer.

No Flow at Devils Creek Bridge in Green Swamp (April 2020)

 

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

• The sharp declines we saw in March came to an end this month, because of high rainfall in April.
• Along the entire river, water levels and flows have either held steady or increased over the past month.
• In the Green Swamp (where the river begins) river levels remained about the same and essentially no flow is still exiting the swamp.
• Farther downriver, flows have increased over the past month.
• Flow increases at Hwy 44 and Hwy 200 (downstream of the Wysong Structure) are also due to an effective hydrilla treatment in the Outlet River of Lake Panasoffkee in early April.
• The table below compares current river levels and flows to what they were last month and last year.

 

 

Tsala Apopka Chain of Lakes:

• More rainfall in April, kept lake levels from dropping as quickly as they had in recent months.
• Lake levels fell about 2 inches in April and are currently about 12 inches lower than they were last year at this time.
• All of the lakes/canals/marshes are currently about 2 feet lower than their high guidance levels.
• All the water control structures (aka “locks”) remain closed, helping to conserve water in the lakes.
• Lake levels are expected to continue to decline over the next month or so as our dry season continues.
• The table below compares current water levels to what they were last month and last year.

 

My Daughter Landing a Nice Bass in the Tsala Apopka Lake Chain (April 2020)

 

Lake Panasoffkee and Wysong:

• Water levels on Lake Panasoffkee fluctuate based on changing inflows and outflows, much like a bathtub or swimming pool.
• Creek inflows remained about the same over the past month.
• Outflows from the lake to the Withlacoochee River increased by about 50% due to a successful hydrilla removal project in early April.
• The combination of greater outflows but more rainfall on the lake, resulted in a net water level decrease of 2 inches in April. In March, water levels fell nearly 4 inches.
• The Wysong water conservation structure remains raised, helping to conserve water upstream and in Lake Panasoffkee.
• The main gate (220 ft wide) is currently fully raised while the independent gate (19 ft wide) has been partially lowered in April, due to an increase in river flows and levels.
• We can expect lake levels to continue to decline over the next month or so, unless our region receives above average rainfall in May.
• The table below compares current lake levels and flows to what they were last month and last year.

 

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

• Downstream from Dunnellon, the Withlacoochee River is influenced by water control structures on Lake Rousseau.
• Inflows to Lake Rousseau include combined flows from the Withlacoochee and Rainbow Rivers.
• Withlacoochee River flows (which depend on rainfall and runoff from adjacent lands) increased by 23% over the past month.
• Flow in the Rainbow River (which reflects changes in aquifer levels) decreased by 4% over the past month.
• Most of the flow entering Lake Rousseau is still coming from the Rainbow River (a situation we typically see during the dry season).

• Outflows from Lake Rousseau have decreased by about 40% over the past month and are currently much lower than they were at this time last year.
• All flow entering the lake is currently passing through the Inglis Bypass Spillway to the Lower Withlacoochee River.
• The Inglis Main Dam, which conveys excess flow to the Barge Canal, has been fully closed for the past couple months.

 

Best Regards,

Mark

 

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

Chief Professional Engineer

Water Resources Bureau

Southwest Florida Water Management District

 (352) 796-7211, ext. 4410

(800) 423-1476 (FL only)

(352) 279-4493 (cell)

Mark.Fulkerson@WaterMatters.org

 Withlacoochee River Watershed Initiative