And it gets most of its water straight from the sky.
As presented at the Big Cypress Symposium
But that doesn’t mean …
It hasn’t changed over the decades.
In fact, by the time the Big Cypress was saved from development – and designated as natural refuges, parks and preserves – a vast network of canals and levees had already been put in place.
Animation of how drainage altered the watershed
For one, the watershed shrunk.
The headwater delivery system that used to reach high up into the Caloosahatchee and Lake Okeechobee is now diverted to the coasts. Meanwhile, the water that used to flow into Big Cypress from the Everglades has been cut off, or even reversed.
Major drainage preceded conservation of The Big Cypress
We’re not saying we don’t love being a watershed.
It’s the best of all possible foundations to build on. The next step is doing hydrologic restoration projects great and small to get the water right.
When thinking about geography, and hydrology, too.
Historic Phytogeography of South Florida with Present Day SFWMD Features, 2019, by Lexie Hoffart & Nichole Miller, Geographers, SFMWD. View a full scale version of the map here. Find out more about how the map was made here.
The dredging of the Caloosahatchee River, and specifically blowing up of Ft. Thompson Falls in the 1880s, is often invoked as the starting point of drainage of Lake Okeechobee and the Everglades.
In the years and decades that followed, the Caloosahatchee would go on to become the primary outlet for controlling Lake stage, a status it retains to this day. In many ways it functions as spillway for the greater Kissimmee-Okeechobee-Everglades (KOE) flow way, and in particular for the Lake.
Not a single act, direct dredging of the river – including digging a straight channel through its tailwater oxbows, blowing up the Ft. Thompson Falls, connecting it to the Lake, and deepening the channel for nautical purposes throughout – and construction of a vast network of tributary canals that drained into it (from the north and south) occurred over a span of decades. The Caloosahatchee River was a rare case where nautical and drainage interests initially fought against each other but ultimately both won.
The original Caloosahatchee was more reminiscent of a stream in terms of its meanders and relatively shallow depth. The river was sinuous to the point of being unnavigable, requiring larger vessels to “warp-around” the curves, requiring running their bow on the shore and using a rope to swing the boat in the right direction (Antoni et al, 2002). Moreover, the stream stopped short of the Lake, about halfway to be exact, where the smaller (and now dried up) Lake Flirt basin served as its headwater source.
As a result,
Caloosahatchee is now a channelized spillway, not a natural river
Historic Lake Flirt and Lake Bonnet no longer exist,
Modern-day water levels north of Ft Thompson falls are upwards of 10-15 lower than their pre-drainage condition.
The Caloosahatchee doesn’t just drain Lake O, it’s also the primary getaway canal for draining lands to the north and south of the river. This drainage capacity is enhanced by a series of tributary canals along the modern-day river’s entire length.
Not all the water that discharges through the S-79 is from Lake Okeechobee. Approximately half comes from the Caloosahatchee watershed and those tributary canals.
The water table under the Immokalee Rise dropped below the regional surface water table.
Drainage of the Caloosahatchee caused the headwaters of Okaloacoochee Slough to reverse course. At some point Big Cypress Swamp’s pre-drainage watershed now flow north into the Caloosahatchee River, both groundwater (unseen) and surface water as seen at Okaloacoochee Slough.
Today we think of Lake Okeechobee feeding flows into the Caloosahatchee. But prior to drainage, (1) there was no connection from the Lake and (2) the headwaters of the Caloosahatchee actually helped feed water south into the Big Cypress Swamp.
The Big Cypress has long been touted as a “rain driven” watershed.
While that may sounds Utopian at first …
Maybe it has errantly led us down the wrong path.
Perhaps a better way to think of the Big Cypress conservation lands are as derelict ruins of a hydrologic architecture that long since collapsed and that once reached well up towards the Caloosahatchee (as shown on the animated diagram above.)
I‘m not saying we’ll ever get all that back …
But finding ways to connect the swamp to its headwaters are vital to the success of our conservation lands and our community and its water management efforts at large.
The Immokalee Rise is often viewed as the northern “terrestrial” bounds of the swamp.
But “hydrologically” could it have been its source?
The myth of a rain-driven swamp falls apart when you consider its connection to a higher Lake Okeechobee, the flooded Lake Flirt floodplain, Ft. Thompson falls and the underlying karst and porous sands of the Immokalee Rise, prior to drainage of course
Imagine if you would:
A higher pre-drainage Lake Okeechobee, 23 feet above sea level (asl).
A fully intact Ft Thomson Falls that pooled water in the Lake Flirt floodplain, 20 ft asl
Groundwater flowing laterally through the Immokalee Rise’s underlying karst
Rainwater infiltrating down into the porous sands of the Immokalee Rise
Under that scenario, Immokalee Mountain wasn’t a dam at all …
But the underground spigot that supercharged the headwaters of the swamp.
Special thanks to hydrogeologist and swamp emeritus Jack Meeder on this post!