Mid-October update
SFL Weekly Watersheds Summary: Oct 9 – 15

Big Cypress NP. What a difference a month makes. The preserve’s sheetflow regime was flowing at full capacity just a month ago in middle September (tracking at its 5-yr high), but now only a month later flows across US41 and preserve-wide water levels are tracking near their 5-yr low for the middle of October. Keep in mind that early October is the time of year when we typically reach our high water mark, but it also marks the turning point in seasons between our summer rainy season and the onset of a drier mediterranean-esque winter season. This year’s summer rainy season switch seems to have been turned off early. We’ve had 3 consecutive weeks of sub 1 inch rainfall since late September, and pretty much no rainfall to date for the month of October. With 2 weeks to go until the end of the 2006 wet season, preserve-wide rainfall is currently 10 inches below last year’s wet season total (May through October), and about 18 inches below the wettest wet season in recent memory (1995), … but by no means are we unusally dry either. The current 2005 wet season total of 42 inches has already exceeded the sub-40 inch totals of wet season rain that fell in 1994, 1997, 1998, and 2000, … and the 40 inches of wet season rain that fell in 2004. After briefly rising into the mesic lanscape type in mid-September, water levels across the preserve have have steadily dropped over the past couple weeks into the hydric and prairie landscape types. Currrently, wetland water stage is about 4 inches below the 5-yr average for the middle of October.

Lake O. Other than Ernesto, the Lake and the Kissimmee Valley have received very little rainfall this wet season. The Lake and the Kissimmee Basins have both received under 25 inches of rain this wet season. That’s almost 20 inches less than Big Cypress has received over the same time period. The Kissimmee Basin has averaged just under 40 inches of rain for the past 5 wet seasons, and the Lake has averaged around 35 inches for the past 5 wet seasons. The last time this little wet season rain fell on the Lake and the Kissimmee was during the record drought year of 2000, and the Upper Kissimmee Basin has currently received about 4-5 inches less rain than was recorded during the wet season portion of 2000. As a result, Lake stage is currently tracking about 3 ft below its 5-yr mid-October average, 2.5 ft below last year’s pre-Wilma level, and 4 ft below last year’s post-Wilma level. Put another way, the lack of rain this year caused lake stage to only rise 1 ft higher than its mid-June low-water mark (of 12 ft msl), … and amazingly this miniscule 1 ft rise was achieved without the need of any substantial structural discharges from the Lake. This is a major contrast to what happened a year ago in 2005 when the mid-June low-water mark was 2 ft higher than this year (at 14 ft msl), when 45 inches of wet season rain in the Upper Kissimmee Basin fed the lake a steady diet of inflows, and when structural discharges were running at high capacity for most of the summer and fall (ie, the S77 was routinely above 5,000 cfs for most of the summer and fall of 2005), and when lake stage crested 3 ft above its mid-June low-water mark to 17 ft msl. Anyhow, what a difference a year makes.

Everglades. The S12s are the last of the major Everglades structures still flowing. The S11s and S10s are closed, with 2 and 3.5 ft of water, respectively, pooling behind them. The S12s are currently flowing at around 2000 cfs, which is about 1000 less than the October 5-yr average. The last time so little water was discharged through the S12s was the summer of 2000. Of interest, the S333 has been openned for the past 2-3 weeks and is flowing at about 800 cfs. With the S344 being closed, this is allowing that 800 cfs through the culverts under the NE Shark River Slough section of US41. This means that as of this week, a total of about 5000 cfs of headwater flows are flowing under US41 into the Park: 1/5th into NE Shark River, 2/5ths through the S12s, and another 2/5ths from the park’s headwater preserve over in the Big Cypress. Water levels in the park seem to be mostly tracking at the transition between the bayhead and ridge landscape type, at about a 1 ft water depth. To the north in southern 3A, water levels are tracking in the tree island landscape type at about a 3 ft water depth.

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