MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       December 4, 2007

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

A few showers south this morning, then cooler. A cold front across the southern end of the District will push into the Keys later today and then stall over the Florida Straits tonight. Some light rain and showers will affect the southern tip of the District today and then cooler temperatures and dry conditions will spread over the area behind the front tonight through Thursday. As the old frontal boundary lifts back north ahead of the next frontal system, some spotty showers will return south Thursday night and then scattered showers mainly east Friday and Saturday.  The next ten days precipitation outlook is below average with low confidence.

 

Kissimmee Watershed

 

Over the last 7 days, the upper Kissimmee Basin received 0.11 inches of rainfall and the lower basin received 0.19 inches.  The total rainfall for November was 0.37 inches (15% of normal) for the upper basin and 0.37 inches (17% of normal) for the lower basin (Daily Rainfall Report for 12/01/07).  During the last week, water levels in most of the upper basin lakes decreased slightly from evapotranspiration.  Lake Tohopekaliga remains at the high elevation of the regulation schedule (high pool) because of inflow from Shingle Creek.

Water levels in Lakes Kissimmee, Hatchineha and Cypress are approximately 2 feet below regulation schedule.  The only releases being made in the upper basin are at S-65, which is discharging approximately 250 cfs.  Flow has been reestablished to the Kissimmee River for 132 days (S-65 re-opened on 07/18/07).  In the river channel of the Kissimmee River, the concentration of dissolved oxygen ranged from 5.17 mg/L – 7.92 mg/L (mean 6.7 mg/L) during the past week.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.23’ NGVD, which is 0.06’ lower than a week ago and 0.13’ lower than a month ago.  The current stage is 2.01’ lower than it was a year ago and 4.68’ below its historical average for this time of year.  Total reported surface inflows declined from last week and are limited to flows of 135 cfs from the Kissimmee River. No outflows are reported.

During November, 22 of the 27 water quality sampling sites had sufficient water for sampling.  Lakewide, TP averaged 127 ppb and TSS averaged 41 mg/L.  These concentrations are similar to those measured in October.  Average TP at nearshore sites increased from 52 ppb in October to 80 ppb in November and TSS increased from 10 mg/L to 19 mg/L. Monthly phytoplankton monitoring was performed last week and no algal blooms were observed.

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  Discharge at S-97 on the C-24 Canal averaged 0 cfs.  Discharge at S-49 on the C-23 canal averaged 23.5 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)

7.6 (7.2)

9.1 (8.6)

 

HR1 (N. Fork)

9.5 (9.0)

12.8 (10.9)

 

Roosevelt Bridge

13.3 (12.8)

13.7 (12.9)

8.0 – 25.0

A1A Bridge

21.4 (22.3)

26.4 (26.6)

20.0 – 31.0

Salinity increased this week upstream of the Roosevelt Bridge.  Both the surface and bottom salinity are in 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 128 mg/l.  Average salinity increased throughout the estuary last week except at S-79. 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)

13.6 (14.7)

14.4 (15.0)

Rt. 31 Bridge

13.8 (13.5)

16.1 (14.9)

I-75 Bridge

14.0 (13.4)

17.0 (15.7)

Ft. Myers Yacht Basin

19.1 (19.0)

20.2 (19.2)

Cape Coral Bridge

24.0 (23.7)

27.2 (26.8)

Shell Point

32.5 (32.4)

34.1 (33.9)

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

FWRI reports that background concentrations of Karenia brevis, the Florida red tide organism, were detected this week at the Gasparilla Fishing Pier (Charlotte County).  All other samples collected between Pinellas and Collier counties contained no K. brevis.  Additional samples collected offshore of Pinellas County, Lee County and the Florida Keys also contained no K. brevis.

 

Water Conservation Areas

 

Dry season recession predominates in most regions but the rate of decline was generally slightly less that of last week.  The exception was NW WCA 3-A where water levels increased slightly, probably due to the rainfall event.  Water depths decreased by 0.04’ in WCA-1, 0.11’ in WCA-2A, 0.05’ in WCA-3A, 0.09’ NESRS, and by 0.04’ 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

 

Trends for ENP wetland water levels were mixed for the week.  The water level has remained remarkably constant in Shark River Slough (@ P33), holding near 1.3’ above ground surface for yet another week (although still low for this time of year).  In the southern part of the system, water level declined by 0.6” at Craighead Pond and by 1.2” in the panhandle at EVER6 over the week.  Taylor Sl. Bridge saw water level drop by nearly 3” last week (less than last week’s decline, and not unusual for this time of year).

Salinity either decreased slightly or remained stable across Florida Bay last week.  Salinity concentrations fluctuated throughout the week at Trout Ck. & Taylor River, declining into single digits by the middle of the week.  In the Taylor River ponds salinity remained below 1 psu over the entire week.  Salinity concentrations at the Little Madeira Bay mouth platform held in the mid-teens throughout the week.  In the north-central Bay areas, Terrapin Bay and McCormick Creek salinity dropped from near 20 psu at the beginning of the week down towards 10 psu by the weekend.  In central Florida Bay, Whipray Basin remained well below 30 psu for another week (though data were only avail. through Friday, 11/30).  In the SRS outflow at Tarpon Bay, salinity decreased slightly to 5 psu by Sunday, 12/2.  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 slightly this week – and are now below their historical average conditions for this time of year.  Water levels in the coastal areas of Lower and Upper East Coasts 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.


 

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