M E M O R A N D U M

 

TO:                 Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:            SFWMD Staff Environmental Advisory Team

 

DATE:                        September 30, 2008

 

SUBJECT:     Weekly Environmental Conditions for Systems Operations

 

Summary

 

Inflows from the tributary basins have continued to taper off and are now in the wet tributary hydrologic conditions.   Stages in Lake Okeechobee (Lake) are within one foot of the intermediate band.  The LORSS recommended discharges are up to 3000 cfs at S-79 and up to 1170 cfs at S-80, and maximum practical discharges to the south if desired or with minimal impact.  The United States Army Corps of Engineers (USACE) initiated a second pulse release on September 16th, with an overall release average of 3000 cfs at S-77 and 1500 cfs at S-80.  Conditions in Lake Okeechobee are fair, with some areas of algal bloom formation on the Lake, and conditions in the estuaries are poor.

 

Background

 

Wet again Tuesday, then drier Wednesday and Thursday.  An old frontal boundary remains across the District and upper level energy continues to stream across the area.  Expect areas of rain and embedded shower activity to move across the District Tuesday afternoon and evening with heaviest activity focused across the southern half of the District.  The front should push south of the District overnight so fairly dry conditions are expected Wednesday and Thursday.  A low pressure system is forecast to develop in the northwestern Caribbean Wednesday so the front should creep back northward into the District bringing a return of rains Friday and Saturday.  The next ten days precipitation outlook is above average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received approximately 0.64 inches of rainfall to bring the monthly total to 2.37 inches (41% of average).  The lower basin received approximately 0.85 inches to bring the monthly total to 2.34 inches (42% of average.  Water levels in all of the upper basin lakes continue to closely follow their regulation schedules except for Lakes Kissimmee, Hatchineha and Cypress which are slightly below regulation and declining.  Releases from the upper chain of lakes have ceased except for minor releases (<100 cfs) from Lakes Myrtle, Hart, Gentry and Alligator.

 

Discharge from Lake Kissimmee decreased from 800 cfs to approximately 300 cfs and discharge at S65C is down from 1700 cfs to 700 cfs.

 

Water depths on the floodplain within the restoration project area have decreased by about 0.5 to 1.0 foot over the last week.  Floodplain depths in the restored area range from 0.5 to 2.0 feet in general.

 

From 9/23/08 to 9/30/08 dissolved oxygen (DO) concentrations in the Kissimmee River ranged from 1.3 mg/L to 4.6 mg/Land averaged 2.9 mg/L, a significant increase from last week.  DO concentrations were above levels of concern most of the time over the past week.


Lake Okeechobee

 

According to the United States Army Corp of Engineers (USACE) web site, Lake Okeechobee stage is 14.93’ NGVD, which is 0.13 feet lower than a week ago, 0.58 feet higher than a month ago, and 5.09 feet higher than it was a year ago.  The current stage is 0.06 feet above the historical average for this date, and 1.16 feet above the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 1111 cfs (no report for S133), with the greatest contributions from the Kissimmee River (454 cfs), S71 (152 cfs), S191 (275 cfs), S129 (102 cfs), Fisheating Creek (82 cfs).  No back-pumping from the Everglades Agricultural Area (EAA) is occurring at this time.  Pulse releases to the estuaries continue at 1797 cfs through the S77 and 568 cfs through the S308. Other outflows include 192 cfs to the L8 at Canal Point.

 

The bloom that was reported in the northern part of Lake Okeechobee and in Fisheating Bay last week has been identified by a District contracted phycologists.  Chlamydomonas, a non-toxin producing green alga, was the dominant species.  The cyanobacteria Microcystis and Planktolyngbya were also present but in low numbers.  Toxin concentrations are not yet available.  A crew will be on a helicopter flight Tuesday afternoon and will report on current condition of the bloom.

 

St. Lucie Estuary

 

During the last week, an average discharge of 858 cfs occurred at S-80 from C-44 and 971 cfs at S308 with no discharge at S-97 from C-23 or S-49 from C-24.  The current weekly average salinities (in bold) at the four monitoring sites in the St. Lucie are given below in parts per thousand (ppt), along with the previous week’s (in parenthesis).

 

 

Weekly Average Salinity (ppt)

 

Sampling Site

Surface

Bottom

Envelope

Palm City Bridge (S. Fork)

1.14 (0.33)

2.08 (0.38)

 

HR1 (N. Fork)

4.73 (2.23)

9.57 (5.45)

 

Roosevelt Bridge

7.02 (4.32)

10.30 (6.36)

8.0 – 25.0

A1A Bridge

16.49 (14.77)

NR  (23.42)

20.0 – 31.0

 

Compared with the previous week, average salinity increased about 0.7 ppt in the South Fork to about 3-4 ppt in the rest stations of the estuary.  All four monitoring stations are reporting salinities below the preferred range, except for the bottom salinity at A1A Bridge.  Salinity conditions in the estuary are still considered to be poor based on the salinity preference of the oyster, Crassostrea virginica, and location in the estuary.

 

Caloosahatchee Estuary

 

An average weekly discharge of 5032 cfs occurred at S-79, 3558 cfs at S-78, and 3655 cfs at S-77.  The concentration of chlorides at the Olga Plant was 53 ppm yesterday, up from 43 ppm at the beginning of this reporting period.  The current weekly average salinities (in bold) at the six monitoring sites in the Caloosahatchee Estuary are given below in parts per thousand (ppt), along with the previous week’s (in parenthesis).


 


 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

0.22 (0.24)

0.22 (0.24)

Rt. 31 Bridge

0.22 (0.24)

0.22 (0.24)

I-75 Bridge

0.25 (0.26)

0.26 (0.27)

Ft. Myers Yacht Basin

0.24 (0.34)

0.24 (0.36)

Cape Coral Bridge

1.76 (3.45)

2.57 (5.17)

Shell Point

13.30 (16.66)

17.42 (19.42)

 

In the estuary, freshwater conditions extend from S-79 downstream to Cape Coral Bridge.  Salinity conditions in the upper estuary east of Fort Myers are good (30 day average at Fort Myers equals 0.30 ppt).

 

Compared with the precious week, a decrease in average salinity of about 2-3 ppt occurred between Cape Coral Bridge and Shell Point.  Salinity at Cape Coral Bridge is below the preferred ranges for both oyster, Crassostrea virginica, and seagrass, Halodule wrightii.  Salinity at Shell Point is oscillating with the tide between about 29 ppt to 4 ppt.  Therefore, conditions in the lower estuary between Cape Coral and Shell Point are considered poor.

 

Fish and Wildlife Research Institute (FWRI) reports that no Karenia brevis, the Florida red tide organism, was detected this week in water samples collected alongshore between Pinellas and Monroe counties.  Monitoring data collected by the River, Estuary and Coastal Observing Network (RECON) of Sanibel-Captiva Conservation Foundation (SCCF) indicated that Chlorophyll concentrations over the last week were about 4.5-5.5 ug/L at Fort Myers and 1.5 to 4 ug/L at Shell Point.  The dissolved oxygen (DO) concentration at the two locations ranged from about 4 to 6 mg/L.

 

Water Conservation Areas

 

Water levels are rising again with the week’s rainfall except for WCA-2A, where depths decreased by 0.29 foot.  Average water stage changes in each of the Everglades areas are below.

 

CHANGE:       WCA-1:           0.07 ft             WCA-3A:         0.06 ft

WCA-2A:         -0.29 ft             WCA-3B:         0.16 ft

WCA-2B:         0.12 ft              NESRS:          0.40 ft

 

Water depths in the Greater Everglades (GE) range from a high of 4.11 feet in the southern region of WCA-2B to a low of 1.36 feet in central WCA-1.  Depths over large areas of the GE exceed 2.5 feet, a generalized threshold for tree island inundation.  Continuous inundation beyond 120 days potentially threatens the health of trees on the tree islands, Inundation Days are now being tracked.  The southern region of WCA-3A is now 63 days above the tree island threshold, the ponded region of WCA-2B is now 77 days above this threshold, and northern and central areas of WCA-2B and -3A are 28-49 days into this 120 day period.  The declining stages in central WCA-2A have dropped depths below this general threshold.

 

Stages in WCA-1 have risen slightly this week but are still below the regulation depths and need to continue to rise.  WCA-2A stages continued to drop but not as much as last week (-0.29 foot compared to -0.62 foot), but are getting closer to their regulation stage.  This conservation area has now been above regulation for one full year. WCA-3A stage has risen slightly this week and has been above regulation since mid-July.

 

Everglades National Park

 

Rainfall prior to the weekend was light to moderate across much of Everglades National Park (ENP) and Florida Bay but heavier Monday.  The highest rainfall totals were to the west, with areas of Shark River Slough receiving at over 2 inches of rain, with particularly heavy rainfall last Tuesday.  The basin-wide spatially-averaged weekly RAINDAR totals were 3.0" and 2.12" in the ENP and C-111 basins, respectively.

 

Data from ENP were not available for the full week, so this report covers the period only through Friday.  Stages in ENP wetlands showed mixed trends last week in response to spatially variable rainfall.  Water levels rose 0.6" in Shark River Slough (station P33) but remained nearly unchanged at Taylor Slough Bridge for the 5 day period.  To the south, stages decreased during the same period by approximately 1” at Craighead Pond and 0.25" in the ENP panhandle (station EVER6).

 

Salinity trends across Florida Bay were also mixed last week.  Seasonably normal salinity was reported in most nearshore areas, including the Little Madeira Bay mouth (mid-upper 20s).  The creeks feeding Florida Bay measured near average salinity before sharply increasing over the weekend into the 20s caused by a flow reversal (high tides) that sent Bay water northward. Taylor River Pond was stable for much of the period (under 10 psu), though data for Pond 5 (USGS platform) indicated that the flow reversal increased salinity in these areas to above 20 psu by the weekend.  District staff will not report on the Taylor River platform 30 day moving average salinity (used for tracking the Florida Bay MFL criterion) until receiving updated data through the weekend.  Salinity also remained near seasonal norms in the north central Bay (low-mid 20s in Terrapin Bay and McCormick Creek) before rapidly increasing over the weekend following a flow reversal.  Salinity at the central Bay platform at Whipray Basin was stable, remaining in the mid-upper 30s (prior to the weekend).  Salinity remained near seasonally normal concentrations in upstream reaches of Shark River (Tarpon Bay platform, where salinity is nearly fresh, under 1 psu.

 

Wildlife

 

The Fish and Wildlife Conservation Commission reported that a large percentage of the deer populations of WCA 3A, Holey Land and Rotenberger have dispersed to the levees.  They have observed 200 or so deer on the L5 levee alone.  While FWC lacks good population estimates of the total deer population, they believe that the total deer population is less than 1000 animals.  Health of the deer appears to be declining; the numbers of dead deer are increasing, and the bucks are shedding their antlers early.  Another species that appears to be highly stressed is marsh rabbits.  Large numbers of dead marsh rabbits are being found in WCA-3A.

 

 

Water Supply

 

Water levels generally declined slightly across most of the District, although there were some areas of localized variability.  Water levels in the upper and lower Kissimmee Basin are now near or slightly below their average conditions for their respective periods of record.  Water levels in the Lower West Coast are mostly above their historical averages although wells in the upper Caloosahatchee River Basin are now below their historic conditions.  Water levels in the Lower East Coast are now near or slightly below their historical averages.  Water levels in the Upper East Coast remain above their historic averages and are close to their highest recorded values.  Surface and groundwater levels in Water Conservation Areas 1, 2 and 3 continue to remain above their historic averages this week – the highest recorded levels were within Water Conservation Areas 2 and 3.

 

All eleven water supply risk indicator parameters are now in the “low” risk category, including the CPC Precipitation Outlook, Palmer Index for Tributary Conditions, the Lake Okeechobee Seasonal and Multi-seasonal Net Inflow Forecast, and Water Conservation Areas 1, 2A and 3A.  The projected Lake Okeechobee Stage and LEC Service Areas 1, 2 and 3 (as a result of the removal of water restrictions) are now in the “low” risk category.

 

LORS2008 (Lake Okeechobee Regulation Schedule)

 

Stages in Lake Okeechobee are within one foot of the intermediate band, and tributary conditions are wet, which calls for discharges of up to 3000 cfs at S-79 and up to 1170 cfs at S-80, and maximum practical discharges to the south if desired or with minimal impact.  The United States Army Corps of Engineers (USACE) initiated a second pulse release on September 16th, with an overall release average of 3000 cfs at S-77 and 1500 cfs at S-80.

 

 

 

 

 

 

CC:      George Horne

 


 

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