End of the year rainfall totals are in
SFL Weekly Watersheds Summary: Dec 25-31

RAINFALL. Despite the last little bit of rain we had this December, it wasn’t enough to save 2006 from being a low rainfall year for south Florida. The Big Cypress and Southwest Coast basins led the way with 50 inches of rain for the year, which is 8-10 inches below the 58-60 inch annual average for both areas. The least amount of rain for the year fell in the Lake O, Kissimmee, and Martin-St Lucie basins. Each of those basins recorded under 35 inches of rain for the 2006. To put that into historical comparision, the Upper Kissimmee, Lower Kissimmee, and Lake O basins have averaged 58, 50, and 45 inches of rain per year, respectively, over the past 10 years, so this year’s mark of under 35 inches is more reminiscent of the 2000 drought year than the wetter past couple years. The Water Conservation Areas and Lower East Coast fell in the middle, receiving around 45 inches of rain for the year basin-wide, which is just a notch below the ~50 inches per year average for those areas.

BIG CYPRESS. The timing of the rainfall is often as critical as the volume. Seventy-five percent of this year’s rain (38 inches) fell in the short 4-month core summer months of June, July, August, and September; and 44 percent (22 inches) fell in July and August. This abundance of rainfall over a such a short time pushed water levels very high very quickly, briefly touching the wetting front up into the mesic pinelands of the preserve. The end of our traditional rainy season was rainless in comparison, and stormless as well, which quickly dropped water levels several inches below average conditions for most of the fall. Preserve-wide water levels enter the new year on a slight uptick as a result of the 1.6 inches of rain we’ve received in December. Water levels are currently holding at the transition zone between wet prairie and tall cypress. This means that we have a very shallow (0-1 inches) and patchy presence of water in our wet prairies, but still a full half foot of water still standing in our tall cypress habitats. You can still expect to find a full foot of water in our swamp forest and marsh habitats.

EVERGLADES. Water depths in southern 3A (Site 65) continue to hold steady at a 2.5 ft depth. Water depths in central 3A and 3B are a half foot lower, both at around 2 ft deep. Its interesting to note the difference in water recession rates since late September for Site 64 (in central 3A) and nearby Site 71 (in 3B). In that 3-month time period, stage at Site 64 has dropped ~1.5 ft in comparison to only a ~0.5 ft drop at Site 71. This difference reflects water management efforts to control seepage into the Biscayne Aquifer at its headwater surficial connection to 3B. Stage in 3B is strategically kept lower relative to 3A during the peak summer months in order to minimize seepage and water loss to the underlying aquifer, and in turn, stage is sustained in the winter months to maintain headwater recharge into the aquifer for downstream water supply withdrawals and to keep saltwater intrusion at bay.

Water depths in northern 3A (north of I75 at Site 63) are currently just under a foot deep. Regulatory stage for 3A has held steady for the month. Its currently tracking about a half foot lower than a year ago at the start of 2006. Down in the Park water depths in Shark River are around 0.75 ft deep, about 0.75 ft below last year’s start of the year level, and about 0.5 ft below the 5-year average for the start of January. Up in Loxahatchee, the 6 inches of mid-December rainfall boosted regulatory stage up to a similar level as the 5-year average and last year’s start of the new year.

LAKE O. Lake stage ended the month at the same elevation it started the month, around 12.15 ft msl. This places the lake stage about 1.5 ft below the bottom of the lake’s interior littoral zone, about 3.5 ft below the 5-year average for the start of the new year, and about 3.5 ft below the start of last January.

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