Much of South Florida at new 5-year lows for mid March.
SFL Weekly Watersheds Summary: March 12 – 18

WEATHER. The Dry Season marches on. Big Cypress National Preserve has received only 5.4 inches of rain since the start of November. Over the past 10 years, (which includes the wet El-Nino stoked winter of 1998), the preserve has averaged 9 inches of rain by this point in the dry season, so we’re on the low end of the spectrum this year. We’re currently on pace to make it three consecutive “dry” Dry Seasons in a row. Don’t forget that this year’s Dry Season “dryness factor” is magnified by merit of this year’s Wet Season fizzling out early, launching us into the dry season mode a month early in early October.

BIG CYPRESS. It’s unusually dry out in the preserve for mid May. The preserve’s last bastion’s of wetland habititat (its swamp forest and marsh communities) went dry a week ago. Preserve-wide stage is now at a new 5-year mid March low. Mid March of last year water levels were still hanging around in our swamp forest and marsh wetland communities. Fast forward 365 days to today and preserve-wide stage is 11 inches lower. The preserve’s southeast corner remains the wettest. It is still holding water in its slough and marsh wetland communities. Suffice it to say we’re on the dry end of the equation, but still not as dry as middle March of 2001 when preserve-wide stage was 8 inches lower than today. In 1998, our wettest winter of recent past, preserve-wide water levels in middle March of that year were 2.5 ft higher than we’re seeing out there today, and still wetting as high as our hydric pinelands. In comparison, our hydric pinelands went dry in late October of this year. That was five months ago! In summary, water levels are tracking low in the preserve, and we still have a solid half dozen dry season weeks left, if not more, until regular Wet Season rains return.

EVERGLADES. All the watersheds in the parochial Everglades are also at or below their 5-year low-water marks for mid March. Regulatory stage in Water Conservation Area 3A is currently about 9 inches below mid March of last year. Sloughs have now gone dry in 3A north of I75 and in the northern part of the Park just south of US41. Southern 3A is showing current water depths of 1.5 ft, which means that sloughs and ridges are still fully flooded in that area. Interestingly, water is flowing rapidly out of 3A through the S333 at around 500 cfs with an equal amount exiting at S334. This may be associated with water being tapped for water supply purposes over on the east coast. Also of interest, slough habitat in WCA 2 typically go dry for a few months in the late winter and early Spring. In comparison, slough habitat in WCA 1 (Loxahatchee) to the north tends to stay flooded, albeit shallowly, all year round, which makes it similar to southern 3A in that respect. Water is currently pooling around 1 ft behind the S12s, 2.5 ft behind the S11s, and over 3 ft behind the S10s.

LAKE O. Lake stage has now dropped below 11 ft msl. That marks the first time that the Lake has been below 11 ft msl since a closely-watched half-year span from January 2001 to July of 2001. There’s some minor discharges flowing south out of the Lake through the S354 and S351 structures, presumably for water supply purposes. The big (and invisible) water budget elephant in the room is evapotranspiration. Its evenly applied withdrawal from the Lake’s surface is the equivalent of an Ernesto-esque deluge of +5,000 cfs flowing through an individual structure. Evaporation is the black matter of south Florida’s water budget universe. We often forget about it because we cannot visualize it as clearly as a stream of water moving in a channel or rushing through a gate, but it constitutes a full half of south Florida’s water budget pie.

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