Wk of 6/26-2: End of June summary
Lake O stage seems to have bottomed out at 12 ft above sea level, but has not yet begun to rise. Last year this time lake stage was 4 feet higher. As it stands now, lake levels are still 1.5 feet below the bottom of the littoral zone (13.5 ft above sea level) and about 1.25 ft below the 5-year average for the start of July.
Down in Loxahatchee, water levels are still flooding at the slough level. Just to the south in WCA2, water levels have not yet risen to the slough level. Both sites 2-17 and 2-19 are reporting an absence of surface water, although just upstream of the S11s surface water is backing up above the slough level into the ridge zone. Interestingly, water levels at Site 99 down in WCA2B have declined about a foot since the start of June, whereas the water levels just upstream in 2A have stayed steady during the same period. This must be caused by either (1) lack of water flowing from 2A to 2B, (2) water being drained out of 2B (for water management reasons), or (3) a combination.
Down in Water Conservation 3, regulatory stage has risen about a half foot from its early June low water mark. In the area north of I75, surface water is now flooding in the slough zone. Surface water is pooling up higher to the south where it accumulates on the north side of US41. Both sites 65 (in 3A) and 71 (in 3B) are showing water levels to have risen into the bayhead landscape type zone. If you click the “outer diamond” (http://www.fgcu.edu/bcw/WCA3A/Ha65.gif) for site 65 you’ll see by looking at its period of record (using the hydrologic calendar) that for the past 10 years its low-water mark rarely (if ever) drops below the ridge landscape type. In comparison, the hydrologic calendars for the rest of the sites in the conservation areas show their low-water marks to routinely drop below the slough landscape zone and become dry. I don’t know which one is more natural, probably somewhere inbetween.
Down in the park, the S12s are not yet flowing. This time last year the S12s were flowing at a combined total of 2500 cfs, but that was due to all of last year’s big June rainfall, and in attempt to provide relief to rising water levels in 3A. You can look at period of record for flow through each of the S12 structures if you click on the individual S12 structures on the interactive ENP map. You’ll see a very noticeable difference in the magnitude and duration of flow between the S12A and the S12D. The S12D stays open longer, plus its in a deeper part of the system which allows more water to move through it. The marl prairie south of S12A tends to minimize flows through it relative to the other S12 structures. At this point, with all the rain we’ve received, I would suspect that inflows to the park are occurring across US41 in the Big Cypress. Hopefully that will be reflected in the graph in time for next week’s update. Special thanks to the USGS-ENP partnership to monitoring flows across the trail. That’s one of the best and longest hydrologic data sets we have in the Everglades.
Over in Big Cypress, water levels have rebounded over 3 feet from the mid-May low water mark, and are now tracking very closely to the 5-year average for early July. Surface water is now flooding at the prairie and cypress landscape level throughout most of the preserve, although the area to the north of I75 is still only reporting water in the lowest wetland zone, the swamp forest. A rainy end to June helped make up for lost ground earlier in the month. Preserve-wide, this year’s June rainfall chimed in at 8.1 inches, only about 2 inches below the 10-year June average.