MEMORANDUM

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       November 27, 2007

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Light rainfall likely through Thursday.  A weakening cold front should overtake a weak trough over south Florida later today.  Enough moisture, heating, and convergence should set off a few showers south of the Lake.  The front will stall and wash out over south Florida tomorrow, but some showers will linger through Thursday when another weakening front moves down the peninsula.  Drier air should then filter in by Friday leaving a dry and warm weekend.  Next chance for mainly minor rains arrives next Monday.  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 1.51 inches (60% of the long-term average) and the lower basin received 0.03 inches to bring the 30 day total to 0.92 inches (40% of the long term average).  During the last week, water levels in the upper basin lakes have not changed.  Water levels in Lakes Kissimmee, Hatchineha and Cypress are approximately 2 ft below regulation schedule.  The only releases being made in the upper basin are at S-65.  Discharge at S-65 is approximately 250 cfs.

 

Flow has been reestablished to the Kissimmee River for 125 days (S-65 re-opened on 07/18/07).  In the river channel of the Kissimmee River, the concentration of dissolved oxygen ranged from 6.0 –7.9 mg/L (mean 7.2 mg/L) during the past week.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.29’ NGVD, which is 0.03’ lower than a week ago and 0.04’ higher than a month ago.  The current stage is 1.97’ lower than it was a year ago and 4.69’ below its historical average for this time of year.  Total reported surface inflows of 312 cfs are considerably lower than last week and include flows from the Kissimmee River (286 cfs) and the L8 at Canal Point (26 cfs).  No outflows are reported.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  Discharge at S-97 on the C-24 Canal averaged 64 cfs.  Discharge at S-49 on the C-23 canal averaged 2 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)

7.2 (4.3)

8.6 (5.7)

 

HR1 (N. Fork)

9.0 (8.1)

10.9 (11.0)

 

Roosevelt Bridge

12.8 (11.0)

12.9 (12.3)

8.0 – 25.0

A1A Bridge

22.3 (18.4)

26.6 (24.3)

20.0 – 31.0

 

Salinity increased this week throughout the estuary.  Both the surface and bottom salinity are now up to the preferred range at the Roosevelt Bridge, and at the A1A Bridge. Based on the salinity tolerances of the oyster, Crassostrea virginica, salinity conditions in the estuary are good

 

Caloosahatchee Estuary

 

No discharge occurred at S-79 last week.  The concentration of chlorides at the Olga Plant is 147 mg/l.  Average salinity increased throughout the estuary last week.  Weekly average salinities for specific sites are given below in parts per thousand (ppt).  Current weekly averages (in bold) may be compared to last week’s data (in parenthesis).

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

14.7 (13.3)

15.0 (14.0)

Rt. 31 Bridge

13.5 (12.0)

14.9 (14.0)

I-75 Bridge

13.4 (12.0)

15.7 (14.6)

Ft. Myers Yacht Basin

19.0 (17.1)

19.2 (18.4)

Cape Coral Bridge

23.7 (22.8)

26.8 (25.1)

Shell Point

32.4 (30.3)

33.9 (31.5)

 

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

 

FWRI reports that water samples collected alongshore this week between Pinellas and Collier counties contained no Karenia brevis, the Florida red tide organism, with the exception of one sample collected at Englewood Beach (Charlotte County) which contained background concentrations.

 

Water Conservation Areas

 

Dry season recession rates predominate in the entire region but not as much as they have for the last few weeks, especially in WCA-2A.  Water depths decreased by 0.08’ in WCA-1, 0.14’ in WCA-2A, 0.1’ in northern WCA-3A, 0.09’ NESRS, but only by 0.03’ in WCA-3B.  Water depths are typically above 2 ft, at this time of year, in the WCAs.  However, on average, all the WCAs (except WCA-2B) have water depths below 2.0 ft.  Stages in WCA-1 are in Zone B, WCA-2A remains well above regulation, and stages in WCA-3 remain below regulation.

 

Everglades National Park

 

Most stations recorded no rainfall over the 7 day period. Everglades National Park (ENP) wetland water levels were generally down for the week.  The exception to this trend was at P33 (in northern SRS) where water levels have been stable.  In southern SRS, water level declined by 1.2” and by 1.6” in the panhandle at EVER6.  With the cessation of pumping from S332D, Taylor Sl. Bridge saw water level drop by nearly 5” last week.

 

Salinity either increased slightly or remained stable across Florida Bay last week.  It was a week of moderate creek flow reversals.  These 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 held in the mid-to-upper teens throughout the week.  In the north-central Bay areas, Terrapin Bay and McCormick Creek salinity was very low early on (just below 10 psu), then increased into the high teens by the latter part of the week.  In central Florida Bay, Whipray Basin remained well below 30 psu for another week.  In the SRS outflow at Tarpon Bay, salinity increased to nearly 6 psu by Sunday, 11/25.  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 continued to decline this week – and are now slightly below their historical average conditions for this time of year.  Water levels in the coastal areas of Lower East Coast are still 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.

 

The Water Supply Risk Measures were unchanged this week.  Six out of eleven water supply risk measures are in the “high” risk category - 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.

 

Chlorides at the Olga WTP on the Caloosahatchee River are now at 140 ppm, although the plant is currently off-line as a result of ongoing repairs and maintenance.

 

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