ORLANDO, Fla. – Even with sunnier skies now, water levels along the St. Johns River remain elevated.
Parts of the river are still in moderate flood stage following last week’s above-normal tides, strong winds, and heavy rainfall from earlier weeks.
Water levels at St. Johns
Right now, a flood warning remains in effect through Tuesday, as water levels are expected to slowly recede.
Flood warning
Along the river, conditions vary by stage: When the river reaches action stage, water begins to cover a few yards; in minor flood stage, docks go underwater; at moderate flood stage, many yards are flooded; and in major flood stage, water begins entering homes and structures.
St. Johns River
So why does it take so long for the water to go down?
The St. Johns River is one of the few rivers in the country that actually flows north — and it does so at an incredibly slow pace. It’s the longest river in Florida at 310 miles long. From the marshes south of Melbourne all the way to Mayport near Jacksonville, the river drops less than 30 feet in elevation — only about an inch per mile. Because it’s so flat, the Atlantic tide can actually push the water backward twice a day, sometimes all the way down to Lake Monroe. When strong northeast winds stick around, that backward flow can last for several days, keeping water levels higher than usual.
When heavy rain or high tides push extra water into the river, it doesn’t just rush out to sea. Instead, it can back up from downstream, especially when onshore winds or tides keep pushing water inland. This “backwater effect” causes the river to rise and stay elevated for days or even weeks after a storm has passed.
That’s why areas near Astor often see lingering high water long after the rain has stopped.
The St. Johns doesn’t flood quickly—but once it does, it takes its time going down.
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