MEMORANDUM

 

TO:                      Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:                SFWMD Staff Environmental Advisory Team

 

DATE:                 September 25, 2007

 

SUBJECT:           Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

No regulatory releases to the south or estuaries are recommended.

 

Background

 

Showers and thunderstorms; heaviest east.  A low has spun up in the upper level trough currently lying east-west across the District.  This upper low is producing very favorable upper level winds over the southern half of the District which should tap ample moisture and allow shower and thunderstorms to redevelop near the south and east coasts and move northwest and west today and tonight.  As the upper low shifts slowly westward, expect a similar pattern Wednesday and Thursday with activity spreading more northward each day.  As the upper low weakens, daily shower activity should drop down a bit Friday before increasing again Saturday and Sunday as a cold front moves into north Florida and interacts with tropical moisture..  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

The upper Kissimmee Basin received 2.18 inches of rainfall over the last 7 days to bring the September total to 4.31 inches (88% of average) and the lower basin received 1.64 inches to bring the September total to 5.38 inches (112% of average) (Daily Rainfall Report for 09/25/07).

 

Stages in most of the upper basin lakes have been stable over the last seven days.

 

Snail kites continue to nest on Lake Tohopekaliga but activity has slowed.  There are 11 active nests including one that is in the early stages.  Many non-nesting snail kites are still using the area (USFWS September 21, 2007).

 

Flow has been reestablished to the Kissimmee River for 69 days (S-65 re-opened on 07/18/07).  Discharge at S-65 continues at approximately 500 cfs.  Increased discharge at S-65C indicates increased basin runoff.  The concentration of dissolved oxygen in the river channel has remained above thresholds of concern for most of the last week with mean daily values ranging between 1.3 mg/L and 4.2 mg/L.  On one day the mean value fell below 2 mg/L.  on another day, the minimum fell below 1 mg/L for approximately 1 hour but the average for that day was above 2 mg/L. The lower values are likely due to cloudy days and local runoff causing increased organic loading

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.78’ NGVD, which is 0.13’ higher than a week ago and 0.25’ higher than a month ago.  The current stage is 3.65’ lower than it was a year ago and remains approximately 5’ below its historical average for this time of year.  Total surface inflows are not reported due to missing data from the S65E (Kissimmee River).  No surface outflows are reported.

Monthly algal bloom monitoring was conducted at 5 sites on the 12th of September.  Chlorophyll concentrations were well below bloom levels (defined as concentrations ≥40 ppb) at 4 sites and just at bloom levels (39 ppb) at one site near the Clewiston water intake.  Algal toxin data for this month have not been reported.  Total phosphorus concentrations averaged 99 ppb, with highest concentrations (213 ppb) at the mouth of the Kissimmee River and lowest concentrations (46-54 ppb) near the western and southern shores.

 

St. Lucie Estuary

 

Release information from S-80 was unavailable the past week.  Weekly average salinities at the four monitoring sites in the St. Lucie are given below in parts per thousand (ppt).

 

 

Weekly Average Salinity (ppt)

 

Sampling Site

Surface

Bottom

Envelope

Palm City Bridge (S. Fork)

6.50

7.64

 

HR1 (N. Fork)

6.31

10.54

 

Roosevelt Bridge

11.37

11.87

8.0 – 25.0

A1A Bridge

18.37

24.10

20.0 – 31.0

 

Salinity declined slightly throughout the estuary.  Both the Roosevelt Bridge and A1A Bridge are within or closely within the preferred ranges.  Therefore, salinity conditions in the estuary are good.

 

Caloosahatchee Estuary

 

During the past week, discharge at S-79 averaged 342.57 cfs.  Chloride concentration at the Olga Plant is presently 75 mg/l.  Average salinity at all monitoring sites in the Caloosahatchee Estuary decreased slightly over the past week due to local runoff.  Data for specific sites are given below in parts per thousand (ppt).

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

5.66

5.66

Rt. 31 Bridge

5.73

6.10

I-75 Bridge

5.27

7.47

Ft. Myers Yacht Basin

10.06

NA

Cape Coral Bridge

17.76

18.88

Shell Point

27.23

30.06

 

Salinity in the upper estuary remains high for this time of year.  The 30-day average surface salinity at Ft. Myers is 11.25 ppt.  Conditions in the upper estuary are fair.  Downstream of the Cape Coral Bridge salinity conditions are good.

 

FWRI reports that no Karenia brevis, the Florida red tide organism, was detected this week in water samples collected alongshore between Pinellas and Collier counties.

 

Water Conservation Areas

 

The declining water levels of last week have been compensated for by the increasing water levels of this week.  Water levels increased more in the northern Everglades (WCA1 was up 0.36 ft and WCA2A was up 0.44 ft) than they did in the southern Everglades (WCA3B was up 0.10 ft and NESRS was up 0.13 ft).  All regions had good inundation rates and depths have significantly improved because all habitats have at least 1 ft of water.  Stages in WCA-1 are below regulation but still in Zone A2. Stages in WCA-2A went up enough to be at regulation and stages in WCA-3 are still below regulation.

 

Everglades National Park

 

Rainfall was patchy across Everglades National Park (ENP) and Florida Bay last week, with much heavier accumulations to the north of the Park.  Despite the surplus rains north of the ENP, most of the ENP wetlands experienced declining water levels last week.  Water level dropped by 4.3” to below the surface at Taylor Slough Bridge (TSB).  The ENP panhandle (station EVER6) water level declined by nearly 2 inches.  To the west in Shark River Slough (P33), water level was down by just over 1” (Note: These data do not reflect the rainfall that fell today (September 25, 2007) over the eastern ENP)

Salinity showed mixed trends across FL Bay last week.  Strong southerly winds from last week’s low pressure system caused flow reversals that increased salinity for much of the latter part of the week in areas of northern Florida Bay & its associated creeks (Trout Creek up to 25 psu, Taylor River mouth up to 20 psu).  Salinity in the TR ponds increased to ~ 15 psu in Pond 5 and 9 psu at Argyle Hendry (station TR) before declining by Sunday, 9/23.  Salinity concentrations in the central Bay areas of McCormick Ck. and Terrapin Bay also increased late last week into the low - mid-30 psu range.  Salinity was more stable at the central Bay station, Whipray Basin (up to just over 42 psu by the weekend).  To the north and west, Tarpon Bay (SRS outflow) salinity increased to 5 psu.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast continue to remain near low levels for their periods of record – although there was some continued recovery in shallow wells in the LWC and UEC this week as a result of local rainfall.  Water levels also rebounded slightly in the coastal areas of Lower East Coast over the past week, but they remain near or above their historical averages.  Surface and groundwater levels in the Water Conservation Areas are near the historic lowest levels recorded for this time of year also.  Water levels in the southern-most portion of Dade County rebounded somewhat, as a result of local rainfall.

 

Six out of eleven water supply risk measures are in the “high” risk category this week – no change from last week - including the projected Lake O Stage (SSM), the Palm Index for Tributary Conditions, the LOK Multi-Seasonal Net Inflow Forecast and Lower East Coast Service Areas 1, 2 and 3.

 

Water Conservation Areas 1 and 2A continue to be in the “low” risk category and Water Conservation Area 3A is now at “medium” risk.  The CPC Precipitation Outlook remains at “low” risk this week, and the LOK Seasonal Net Inflow forecast is now at “medium” risk.

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake O stage – at 9.78’ today - remains in the Water Shortage Management zone and is unlikely to move back into Zone E in the next two months.  The water level in Lake Istokpoga has declined to below the floor of the schedule, and the SFWMD is beginning to initiate the process of requesting a deviation from the current regulation schedule.

 

 

CC:   George Horne