Lake Okeechobee

Okeechobee Foothill?
How time turned a dike into a levee

For as easy as it is to see on a map …

Lake Okeechobee is deceivingly hard to find on the ground.

Map of Lake Okeechobee

The reason?

Hoover Hill would seem partly to blame.

Listen to the podcast to find out more.

Sometimes called a levee and other times a dike

The earthen embankment both blocks the view from its base and promises a scenic vista from its top only to leave you wondering –standing at its crest and looking inward — where the lake starts and if it’s there at all.

Hoover Hill (left) and Lake (right)

With everyone thinking about how to optimally regulate the Lake’s stage, its important to remember that from a design standpoint, the dike-turned-levee was built first and foremost to control (repress) water levels on the outside, not inside, of the levee …

And with the design goal (on the outside) being dry arable ground.

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Hoover’s Hill (to True Scale)
And why you can't see the Lake or Everglades

True to scale cross section of Herbert Hoover Dike as seen at Clewiston, FL

At first glance, the Herbert Hoover Dike appears to tower high above the Lake’s water surface – well above the level that any flood could conceivably overtop – and also seems to be equally stout at its base, to the point that the mound almost seems to be overdesigned.

But the strength of the dike also depends on its internal composition and the foundation where it rests, both of which are faulty to a degree.  The reason?  The dike mammoth dike is composed of native water-solvent limestone sand and shell and also rests on a layer of organic peat (underlain by more porous limestone) that has dissolved and settled over time. 

And so it is: Lake water cannot go overtop the gigantic earthen mound, but it can (and has) found and formed subterranean channels inside and underneath the dike. 

The dike is in fact designed and maintained to accommodate this seepage to a degree.  By merit of its girth and other design features, such as a collector ditch on its exterior side which serves as a slow drip relief valve for the dissipating water pressure within the water blockade, the, the erosional effects of seepage have been kept at bay.  Periodic patching of problem areas (i.e. anywhere seepage features were detected) has also been performed throughout the history of the dike.

Map of modern-day Lake Okeechobee

Everything seemed find until Hurricane Katrina and Wilma passed by in 2004 and 2005.

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Winning Tree

There are cypress trees,

And there are big cypress trees …

As seen in along the banks
of the Caloosahatchee near
Lake Okeechobee

And then there is the “Lone Cypress.”

Standing by its trunk and scanning around (and momentarily closing your eyes) is a good starting point for contemplating what the Everglades might have been prior to drainage, and what it’s become in the modern day.

And a “must see” on anybody’s Everglades bucket list.

ghost of watersheds

Lonely Cypress?
The Lake used to keep it company

If it weren’t for the sign,

I’d probably walk by the tree and not think twice.

This tree originally grew
in knee-deep water along the banks
of an undiked Lake Okeechobee

Or maybe I’d sit on the bench …

And luxuriate in its shade.

And even possibly take note of the old concrete wall.

Today, it is perched over ten feet above
the water line of the Caloosahatchee River
on the outside of the Lake’s perimeter levee

Still, I doubt it would naturally occur to me …

That the concrete wall was the old lock to the Lake Okeechobee before they built the modern one a mile or three upstream.  Or that the tree once served as the sole navigational marker on the Lake.

And the stories this tree could tell if it could speak.

The title on the sign says it all

Fortunately there’s a sign.

Water sources

The S-79 has two sources of water:

Lake Okeechobee and the Upper Caloosahatchee Watershed.

This bar chart shows the total annual volume of water released through the S-79 WP Franklin structure. The red portion of each bar is from the Lake and the blue portion is from the watershed.

If you consider that the Lake holds about 4 million acre feet of water, the equivalent of about one third of the Lake discharged through the S-79 so far this calendar year. But only half of that – or 1/6th Lake – was from the Lake itself (red).

The other 1/6th was from the watershed (blue).

The tree that “stayed put”

For over a century …

The Lone Cypress has stood its ground.

Same tree, then

Or in other words,

The tree has stayed put.

It’s the water level that dropped out from under it, some ten feet.

And now

Once a navigational marker,

The Lone Cypress stands today as a hydrologic reminder …

Of Lake Okeechobee before it was drained.

The tree that made history

If it weren’t for the sign,

I’d probably walk by the tree and not think twice.

This tree originally grew
in knee-deep water along the banks
of an undiked Lake Okeechobee

Or maybe I’d sit on the bench …

And luxuriate in its shade.

And even possibly take note of the old concrete wall.

Today, it is perched over ten feet above
the water line of the Caloosahatchee River
on the outside of the Lake’s perimeter levee

Still, I doubt it would naturally occur to me …

That the concrete wall was the old lock to the Lake Okeechobee before they built the modern one a mile or three upstream.  Or that the tree once served as the sole navigational marker on the Lake.

And the stories this tree could tell if it could speak.

The title on the sign says it all

Fortunately there’s a sign.

Lake o’ decades

Just like Lake O rises and falls over the short term (i.e. seasonally),

It experiences long-term decadal shifts, too.

Animated hydrograph showing current
Lake O stage compared to previous decades

Take for instance the nineties and the aughts (i.e. 2000s):

The Lake shifted from a state of chronic flood (1990s) to prolonged drought (2000s) as driven by some combination of meteorological and management trends.

The chart above shows how current Lake stage measures up to decades past.