11-ft streak over at 511

Lake regains its footing in littoral zone

Rain Or Shine Report for August 11th

The big news in south Florida is that the Lake is back above the 11 ft mark.

It’s been a long road for the Lake.

It started 511 days ago in middle March of 2007. As streaks so often are, it wasn’t such a big deal when it started. (Think Joe Dimaggio’s consecutive game hitting streak at 15. But come game 30, 40, and 55: everyone is watching.)

Surely the summer rains would come, like they always do, and surely the Lake would rise back up above 11 come fall, just like it did in 2001.

But the south Florida’s “old faithful” – its summer rain machine – never switched on in 2007. And when the rains did come, they kept missing the Lake and its headwater Kissimmee, and even southwest Florida for that matter.

Quixotically large drenchings did fall along the east coast (Miami received 13 and 10 inches of rain, respectively in June and October of 2007) and down along the peninsula’s southern fringe.

But as we’ve all come to learn – under its own accord, water knows only one direction: downhill. And in south Florida, that’s a stairstep or two from saltwater.

What’s the significance of 11?

Some of it is symbolic.

But it’s also the level above which the Lake’s littoral zone starts to re-flood with water. At 15 feet the littoral zone becomes completely flooded up base of the perimeter levee. And at 17.5 feet, according to the new LORS regulation schedule, rising water threatens the integrity of the levee.

That’s a bit surprising consider that water stage in Loxahatchee National Wildlife Refuge is currently at 16.5 ft above sea level.

That puts Loxahatchee a full 5 feet higher than the Lake, and 1 ft below what would be a precariously high level for the Lake.

It’s a game of inches in the south Florida hydrology game.
That’s what makes it so fun.

Also, consider that Loxahatchee’s current stage is still lower than it was in back in mid April, during what we think of as the “heart of the dry season.”

Blame that on our unexpectedly high winter and spring rains. Those rains – a pleasant surprise considering the drier-than-normal La Nina forcast – stalled the usual rate of recession, and kept the refuge’s central slough area at a depth of a half foot or higher through the spring.

Compare that to downstream Water Conservation Area 2 where the wetting front dropped below land’s surface for a full month during the spring. (Currently, the central sloughs of WCA2 are holding around a foot of water.)

Going downstream further, slough water depths in southern 3A, just north of the Tamiami Trail, are currently 2.5 ft deep.

And all the S12s are open.

The S12s have been discharging waters into Everglades National Park at a flow rate of above 1000 cubic feet per second (cfs) for the past 3 weeks. That’s not high by historic standards when summer-fall flow rates routinely rise above 2,500 cfs; but consider it a gusher compared to last year’s notable lack of flow through the S12s.

Last year’s full year total of around 30,000 acre-feet through the S12s has already been tripled by this-year’s-to-date 90,000 acre feet.

But compare that to the 1,190,000 that passed through the S12s in 2005.

That raises an interesting question:
Is there any such thing as an average year in south Florida’s water cycle.

The inner circles of old timers will tell you “no”, something along the lines of “I’ve been year 20 years and haven’t seen one yet.”

Well look no further.

Water levels in Everglades National Park’s Shark River Slough have been tracking right along the 5-year average for the past 3 months.

And we can sort of say the same thing for the Park’s headwater preserve: Big Cypress National Preserve, which is currently tracking right along the 5-year average line for mid August.
The same can also be said for the flows flowing through the bridges of the preserve’s 35-miles stretch of Tamiami Trail. Its current 1,500 cfs flow rate is right in tune with the 5 year average for mid August, and about the same as is currently being discharged through the S12s.

That’s not bad for a headwater preserve.

But that’s only for now.

As we’ve said, the south Florida water cycle is a game of inches. And it can change by a foot in the blink of an eye.

That’s what keeps us coming back for more.

And that’s what makes the water cycle the show that never ends.

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