MEMORANDUM

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       November 13, 2007

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

No Lake Okeechobee regulatory releases to the south or estuaries are recommended.

 

Background

 

Showers with minor rains east through tomorrow.  An inverted trough off the southeast coast of Florida is creating low level convergence and launching shallow showers westward over eastern sections of the District.  Most showers are moving and inland over Martin/St. Lucie, but this activity should drift southward this afternoon and evening.  Look for a similar story tomorrow before a cold front sweeps through the state on Thursday.  Dry and cooler conditions will then prevail through the weekend.  Another cold front is expected to move through in about a week, but little rainfall is expected into the Thanksgiving weekend.  The next ten days precipitation outlook is below average with moderate confidence.

 

Kissimmee Watershed

 

Over the last 7 days, the upper Kissimmee Basin received 0 inches of rainfall to bring the 30 day total to 2.59 inches (96% of the long-term average) and the lower basin received 0 inches to bring the 30 day total to 2.29 inches (91% of the long term average).  During the last week, water levels in the upper basin lakes were steady.  Water level in Lake Kissimmee fell approximately 0.1 ft.  The only releases being made in the upper basin are at S-65.

 

Flow has been reestablished to the Kissimmee River for 111 days (S-65 re-opened on 07/18/07).  Discharge at S-65 was decreased from 500 cfs to 250 cfs on Tuesday 11/06/07. In the river channel of the Kissimmee River, mean daily concentrations of dissolved oxygen ranged from 5.6 – 7.6 mg/L (mean 6.8 mg/L) during the past week.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.33’ NGVD, which is 0.04’ lower than a week ago and 0.23’ higher than a month ago.  The current stage is 2.21’ lower than it was a year ago and remains almost 5’ below its historical average for this time of year.  Total reported surface inflows are down from last week due to declining flow from the Kissimmee River (<250 cfs).  Inflows of 685 cfs are entering from the L8 at Canal Point.  Outflows of 408 cfs are reported at the S135 culverts, but these values appear to be in error.

 

Continued high winds prevented completion of the November submerged-aquatic-vegetation (SAV) survey last week and conditions on the lake remain turbid.  In the pelagic zone, average TSS increased from 29.9 mg/L in September to 81.1 mg/L in October and average TP increased from 121 ppb to 222 ppb.  A more modest increase in TSS was documented for nearshore sites (5 mg/L in September and 6.5 mg/L in October) and average TP was 41 ppb during both months.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  The C-24 canal discharge is down from last week to about 294 cfs at S-97.  Discharges at S-49 on the C-23 canal are currently 229 cfs.  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)

2.5 (1.8)

2.9 (1.8)

 

HR1 (N. Fork)

7.3 (2.12)

10.3 (4.52)

 

Roosevelt Bridge

9.7 (5.63)

12.1 (7.91)

8.0 – 25.0

A1A Bridge

17.9 (15.53)

24.4 (23.84)

20.0 – 31.0

 

Salinity conditions improved by increasing this week throughout the estuary.  Both the surface and bottom salinity are now up to the preferred range at the Roosevelt Bridge, but still only the bottom salinity is in the preferred range at the A1A Bridge.  Based on the salinity tolerances of the oyster, Crassostrea virginica, salinity conditions in the estuary are good-fair.

 

Caloosahatchee Estuary

 

S-79 has not been recording discharge values since last Tuesday when the previous average week’s discharge was 24 cfs.  Also, no current chloride values were reported at the structure.  Average salinity increased last week by more than 2 ppt in the upper estuary, including at the Ft. Myers Yacht Basin. Data for specific sites 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)

10.9 (8.1)

12.3 (8.9)

Rt. 31 Bridge

10.2 (7.8)

13.7 (9.1)

I-75 Bridge

10.5 (8.1)

14.2 (12.0)

Ft. Myers Yacht Basin

15.4 (13.3)

17.1 (16.4)

Cape Coral Bridge

22.3 (22.5)

24.5 (24.1)

Shell Point

30.0 (29.5)

30.9 (30.6)

 

Salinity conditions throughout the system remain good seaward of Cape Coral.  Conditions in the upper estuary are poor.

 

Water samples taken last week (reported on Nov 9 by FWRI) detected only background concentrations of red tide (Karenia brevis) along portions of Sanibel Island and at the Naples Pier.  All other samples between Pinellas and Collier counties contained no red tide.

 

Water Conservation Areas

Dry season recession rates now predominate the entire region, setting the stage for significant dry downs and peat burns if these rates continue.  Water depths decreased by 0.17’ in WCA-1, 0.22’ in WCA-2A, 0.14’ in northern WCA-3A, 0.11 in NESRS, but only by 0.05’ in WCA-3B.  Water depths are typically between 2-3 ft, at this time of year, in the WCAs.  However, WCA-1 and WCA-2A are just barely above 2.0 ft and all of WCA-3 has less than 2 ft of water.  Stages in WCA-1 are within Zone A2, WCA-2A remains well above regulation, and stages in WCA-3 remain below regulation.

 

Everglades National Park

The weekly RAINDAR basin-wide spatial average of 0.03” reflected very little precipitation falling over this area (or any part of south Florida) over the week.  The dry season has definitely arrived.  Everglades Nation Park (ENP) wetland water levels were down for the week.  Water level at Shark River Slough (P33) was down by nearly 0.25”, but remains low for this time of year.  To the south, water level declined by 1.2” at Craighead Pond and by 0.8” in the panhandle at EVER6 (between Monday and Saturday).  Taylor Sl. Bridge saw a modest decline (for this station) of 2.0”.

 

Salinity either increased slightly or remained stable across Florida Bay last week.  Salinity concentrations fluctuated throughout the week, from the single digits into the mid-teens at both Trout Creek and Taylor River mouth.  Flow reversals did not make their way far upstream, though, as salinity in the Taylor River ponds remained below 1 psu over the entire week.  Salinity concentrations at the Little Madeira Bay mouth platform remained in the mid-teens throughout the week.  In the north-central Bay areas, Terrapin Bay and McCormick Creek salinity remained low for this time of year, fluctuating between 8 – 16 psu (depending on wind, etc.).  In central Florida Bay, Whipray Basin remained well below 30 psu for another week.  In the SRS outflow at Tarpon Bay, salinity increased a bit to 3.5 psu (still low).  At least as of now, the Bay appears to be well buffered in terms of salinity for the dry season.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast remained somewhat unchanged this week – near their historical average conditions for this time of year.   Water levels in the coastal areas of Lower East Coast are now near or slightly above their historical averages.  Surface and groundwater levels in Water Conservation Areas 1 and 2 are now near or slightly above their historic averages.  Water levels in WCA 3A continue to remain below their historic averages – and were somewhat lower this week.  Water levels in the southern-most portion of Dade County are slightly above average historic conditions as a result of local rainfall.

 

Six out of eleven water supply risk measures are in the “high” risk category this week - the projected Lake O Stage (SSM), the Palmer Index for Tributary Conditions, the LOK Seasonal Net Inflow Forecast and Lower East Coast Service Areas 1, 2 and 3.  Water Conservation Areas 1, 2A and 3A continue to be in the “low” risk category.

 

The CPC Precipitation Outlook and Multi-Seasonal Net Inflow Forecasts remain at “medium” risk this week.

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake O stage remains in the Water Shortage Management zone and is unlikely to move back into Zone E in the next several months.

 

 

 

 

 

 

 

 

CC:   George Horne