Withlacoochee River Update - 5/24/2018

River Levels and Flows Higher as Summer Approaches

 Rainfall:

• Flows and water levels in the Withlacoochee River rise and fall each year depending on rainfall patterns.
• Some years its very dry during the winter/spring, and summer rains only fill things back up to normal levels.
• That was the case last year, until late summer when Hurricane Irma dumped 8-12 inches of rain over the entire region, causing flooding along several areas of the river.
• Other years (like this one) we receive above normal rains during the dry season (Oct-May) and the river is already up before the summer rains come.
• The table below compares our region's monthly rainfall (January through April) for this year, last year and the historical average.

Green Swamp:

• The beginning of the river is in the Green Swamp.
• That doesn’t mean that all of the river’s flow comes from the Green Swamp; there are numerous other tributaries and areas of land that also flow into the river.
• The Green Swamp acts like giant bowl or a sponge, storing rainfall as it fills up during the summer, slowly releasing water downstream.
• There are also many rock outcroppings, log jams and sandbars that the river must overcome.
• Once it does fill, excess rainfall passes more quickly downstream.
• This happened last year as the Green Swamp stored much of our summer rainfall.
• Then Hurricane Irma came, completely flooding the Green Swamp and other flood-prone areas downriver.
• The image below shows the river in the Green Swamp during both low and high water. Hurricane Irma was about a foot higher than the 2004 flood.

Withlacoochee River:

• The geology of our region makes groundwater (aquifer) levels and river flows sensitive to rainfall changes.
• River levels are currently 1 ½ to 2 feet higher than they were this time last year.
• River flows are currently about 8 to 10 times greater than they were a year ago.
• Aquifer levels are also higher and many of the swamplands that border the river, which were dry this time last year, have water standing in them.
• We just didn’t get much of a dry season this year.
• That doesn’t mean the river will flood again this year, but if you live in a flood prone area, please take the necessary precautions.

 If you have any questions about the Withlacoochee River, please let me know and I’ll be glad to meet with you to discuss this complex and magnificent system.

Have a great rest of the week!

Mark

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

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