Water from Ernesto slowly drains out of system
SFL Weekly Watersheds Summary: Sep 11 – 17

RAINFALL COMARISION. We’re nearing the end of the 2006 wet season, but still have another 6 weeks left before it goes into the history books. Here’s a quick tally of the rainfall picture. There’s been about 40 inches of rain in the Big Cypress and Southwest Coast areas so far this wet season (since the start of May). In comparision, the Water Conservation Areas have only received around 30 inches and the Kissimmee and Lake O have received around 20-25 inches. So Southwest Florida has been the wettest so far, but the current 40 inches of wet-season rain still puts Southwest Florida around 8 inches below the 48 inches southwest Florida has averaged over the past 5 wet seasons, as computed from the start of May to the end of October. That leaves us 6 weeks to make up the difference. An El Nino taking grip over the equatorial Pacific may potentially down-grade tropical storms, but that could boost dry-season rains down the road. Through September, the preserve-wide rainfall is tracking very closely to last year’s May-to-September total. The difference last year was that a big 20 inch chunk of rain fell right out of the gates in June, whereas this year the summer rains have been more uniformly spread out after a slow June start to the wet season.

LAKE O. Lake O stage is lapping at the bottom of the lake’s interior littoral zone, and is about 2 ft lower than both mid-September of last year and the 5-yr average for the mid-September. Structural discharges following Ernesto have begun to diminish. Last weeks combined structural flows into the Lake were around 5,000 cfs, which is half the rate of the previous week. Structural discharge through S79 WP Franklin lock was 5,000 cfs, which matches the 5-yr average for mid-September; but again, all of this discharge is from the local upstream watershed, not from the Lake. Structural discharges into the Lake from the Kissimmee (S65E) dropped down to around 1,500 cfs for the week, which is around 4,000 cfs below the mid-September average for the past 5 years.

WATER CONSERVATION AREAS. Regulatory stage is Area 3A has risen over a foot in the 3 weeks since Ernesto passed through. That puts it at the same level as the 5-year average for mid-September (at around 11 ft msl), which is about a half foot below last year’s mid-September stage. Last year’s regulatory stage in 3A peaked in mid July at 11.7 ft msl and stayed about 11 ft msl for 4.5 months through November. This year regulatory stage in 3A is only rising above 11 ft msl for the first time all year. Sites 62-65 are showing water levels lapping into or above the tree islands in all corners of 3A. So its another year of tree island inundation for 3A. The S12s are currently flowing at around 2,000 cfs, which is about 500 cfs below the 5-yr average for mid-September. Over the past 5 years, flows through the S12s peak in mid October at a rate of 3,000 cfs.

BIG CYPRESS NP. We’ve had 5 consecutive weeks of +2 inch rainfall in the preserve, sandwiched in the middle by a 5 inch week from Ernesto. This explains why preserve-wide stage has held steady in the mesic pinelands since the start of September and flows across the Trail are tracking the same as mid-September of last year at around 4,000 cfs. Preserve-wide water levels are currently tracking about 1-2 inches above the mid-September 5-yr average. Bear Island (NW preserve) is the wettest area. Water levels are currently about a foot higher than mid-September of last year. On the low side, water levels in Lostman’s slough (SE preserve) are about a half foot lower than mid-September of last year. This may be in part due to S12A only recently being openned whereas last year S12A was openned in early July due to all the June rainfall.

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