Early fall drydown continues its descent despite frontal rain
SFL Weekly Watersheds Summary: Oct 23 – 29

BIG CYPRESS NP. Water levels in the preserve have been steadily dropping for a solid month now, and are currently tracking in unison with our 5-year low for late October. From a landscape perspective, this means that most of the hydric pinelands are dry, and that water levels are inching down into and below the prairie landscape type. In recent memory, the preserve experienced similar early October drydowns of this magnitude in 2002, 2000, 1997, 1996, and 1991-1993. So its not that unusual an occurrence, … but it is a big difference from what we saw last Halloween when water levels in the preserve were a half foot higher than they are today 365 days later. In fact, 2005 water levels did not drop to our current 2006 level until the end of December. So in terms of time, this year’s drydown is about 2 months ahead of where we were last year.

The frontal storm that passed through southwest Florida dropped about 0.5 inches of rain in the preserve, … but that wasn’t enough to stop the multi-week trend of declining water levels. Its those sorts of storm that can make a difference in how fast and how deep surface waters recede through the fall and early winter season. (Last year we had a +3 inch frontal rainfall event in early February, which was pretty much our only significant rainfall of last year’s dry season.)

LAKE O. The Kissimmee Basin and Lake O have received less than 25 inches of rain since May, and less than 35 inches for the past 365 days, … so lake stage is understandably low. Lake stage is currently tracking at 12.67 ft msl. Going back in time, that means that Lake O stage is currently about 1 ft lower than 30 ago in late September, 4.25 ft lower than 365 days ago on Halloween of last year, and 0.6 ft higher than Halloween of 2000. That was the year of the record drought when ~25 inches of wet season rain (May 00 – Oct 00) followed by ~5 inches of dry season rain (Nov 00 – May 01) caused lake stage to bottom out at a record low of 9 ft msl by late May 01.

EVERGLADES. Water is currently pooling +3.5 ft behind the S10s and around 2 ft behind the S11s. The S12s are still open, at half capacity, and are flowing at a combined rate of 2000 cfs, … which is about 1000 cfs below the S12s late October average. Regulatory stage in 3A is about 1 ft lower than late October of last year. Interestingly, wetland water depth in NE WCA3A (at Site 63) has dropped 1.6 ft since the closure of the S11s about a month ago (from a 3.0 ft depth in late September to a 1.4 ft in late October); … in comparison, wetland water depth in southern 3A (at Site 65) has only dropped a half foot in the same time period, and currently stands at 2.6 ft deep. Water depths in Shark River Slough down in the Park are currently tracking at about a 1.3 ft depth.

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