Lake Okeechobee Conditions Report August 26, 2008:

According to the USACE web site, Lake Okeechobee stage is 13.63’ NGVD, which is 2.29’ higher than a week ago, 2.95’ higher than a month ago, and 4.10’ higher than it was a year ago.  The current stage is 0.62’ below the historical average for this date, and 0.49’ above the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 28105 cfs, with major contributions from the Kissimmee River (14398 cfs), S84 (3524 cfs), S71 (3373 cfs), S72 (1474 cfs), S191 (2453 cfs), and the L8 at canal point (997 cfs).  Backpumping from the EAA is occurring through S4 at 821 cfs.  No outflows are reported and no flow data are available for the S77 or S308.  Total reported flows also do not include an estimated 4000 cfs entering the lake from Fisheating Creek as reported by USGS.

Field crews began conducting post-Fay assessments of water-quality, phytoplankton, and submerged aquatic vegetation (SAV) Last Friday (8/22/08).  Initial reports show increased turbidity across most of the nearshore zone and an absence of algal blooms.  Underwater light conditions for SAV growth ranged from poor (secchi depth:total depth ratio of 0.1) to marginal (sd:td of 0.3-0.4), with the southern shoreline having the least turbidity and the northern shoreline having the greatest.  High flows in Fisheating Creek appear to be maintaining low turbidity across Fisheating Bay.  By contrast, high flows from the Kissimmee are contributing to the resuspension of mud sediments deposited in that part of the lake in recent years. 

Post-storm sampling at SAV sites surveyed just 2-3 weeks ago indicates that the SAV community remains largely intact despite maximum sustained winds near 60 mph along the western shoreline during the storm.  However, continued development of existing SAV beds will be slowed if deep, turbid water conditions persist.  Due to the rapid increase in water levels, many of these beds are now at water depths of 1.0-1.5 m or greater.  However, increased lake stage has also resulted in the rehydration of shoreline areas that historically have contained extensive SAV beds.  An aerial survey conducted on Monday indicated that water clarity in these newly flooded areas is suitable for SAV germination and growth.

Emergent wetland vegetation along the shoreline also remains intact.  Water depths have increased to > 1 m along the outer wall of cattail and spikerush that developed during the drought.  Both of these species are tolerant of deep-water conditions in wetlands such as the Everglades but may not persist at these water depths in the high-energy wave environment of the lake shoreline.  Bulrush stands that form an outer wall along the western shoreline under normal lake stages have reflooded.  Extensive areas of terrestrial herbaceous vegetation that established across the littoral zone during the drought have also flooded.  Transient water-quality problems including high nutrient levels, algal blooms, and low nighttime dissolved oxygen may occur in these areas as this upland vegetation dies and begins to decompose.

 

 


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