King of flows dethroned

S79 has been quiet for past 2 years

Rain or Shine Report for Apr 15

Lake Toho is about a foot higher than mid April of last year. That puts it about 2 ft above its 5-year mid April average.

But you’ll have to take that with a grain of salt: Lake Toho was drained in 2004 to scrap away its benthic muck. That’s thrown its 5-year average numbers all out of whack.

I can’t believe it’s already been 4 years since Lake Toho was drained. That was a life-time ago in terms of water-cycle years: Lake Okeechobee was over 15 ft at the time, and release of additional waters from Toho was the water-management uproar of the day.

Chalk it up as another example of the seasonal whimsies of the water cycle not cooperating with long-term planning efforts.

Now the tables are reversed: Lake O is low (10.5 ft) and Lake Toho is high, at a 10-year high to be exact, standing at 54.5 ft above sea level. You have to go all the way back to 1996 and 1997 to find similarly high Toho stages in April.

What does all that water mean, or more correctly phrased, go?

More flows into the Kissimmee for one. Inflows from the Kissimmee into the Lake rose to over 2,000 cfs last week. Last time April flows from the Kissimmee were this high was the record-setting 2005 flow year, when about 2.3 million acre-feet passed through S65E into the Lake.

That’s about the same volume of water that evaporates from Lake O each year.

What’s the highest April discharge record for the Kissimmee?

That would be 1983 and 1998 – both El Nino years; but 1998 wins the big prize. Kissimmee flow rates topped over 9000 cfs for several straight weeks that dry season, if you can even call it that.

Ironically, the Kissimmee’s two longest high-flow stretches on record (exceeding 5,000 cfs) occurred during the dry season, not the summer wet season as one would expect.

That’s the exception, not the rule.

The Kissimmee typically peaks in late Summer – it has a 5-year September average of just above 5,000 cfs – and then drops to a 1,000 to 2,000 cfs spring-time average.

At least that’s what has happened over the past 5 years. Don’t forget it went flowless in 2006-2007 for 9 straight months.

Compare recent Kissimmee flows to the tailwater structure on the Calooshatchee: the WP Franklin (S79). It hasn’t discharged above 1,000 cfs since October 2006. In September 2006 it topped out at almost 13,000 cfs.

How big is 13,000 cfs?

Over the course of a month it adds up to 780,000 acre feet. Over the course of a year: that would be over 9 million acre feet. That’s never happened, but about half of that amount has.

Back in 2007, 3.9 million acre feet discharged through the S79.

Compare that to only 950,000 acre-feet in 2006 and 110,000 acre feet in 2007. The latter makes the lowest annual volume to pass through the S79 in at least 28 years.

Consider the S79, King of south Florida flows, dethroned … for now.
. . .

More on the Everglades (Loxahatchee, WCA3, The Park) and Big Cypress later, or click into the data dashboard to see for yourself.
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