MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       December 11, 2007

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Some light showers east; increasing shower activity Thursday night through Saturday.  High pressure located east of Florida will maintain mostly dry conditions over the area but breezy northeast to east winds will bring isolated light showers mainly east today through Thursday.  Subtropical Storm Olga is currently near Hispaniola and it is expected to weaken over the central and western Caribbean over the next few days.  Moisture associated with Olga will increase shower activity over the District Thursday night and Friday and then help produce moderate rainfall as a cold front moves through the area Saturday.  Drier and cooler conditions are expected behind the front.  The next ten days precipitation outlook is below average with low confidence.

 

Kissimmee Watershed

 

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 139 days (S-65 re-opened on 07/18/07).  In the channel of the restored Kissimmee River, the concentration of dissolved oxygen ranged from 5.02 mg/L – 8.11 mg/L (mean 6.83 mg/L) during the past week.  Last week, a slight algal bloom was noted in Pool D and Pool C.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.18’ NGVD, which is 0.05’ lower than a week ago and 0.15’ lower than a month ago.  The current stage is 1.90’ lower than it was a year ago and 4.68’ below its historical average for this time of year.  Total reported surface inflows are similar to last week and are limited to flows of 280 cfs from the Kissimmee River.  Total outflows are not reported due to missing data from the S308 and the S352.

 

The monthly submerged-aquatic-vegetation (SAV) survey was completed last week.  The macroalga Chara remains the dominant SAV species and was found at 20 of the 33 sites sampled.  This distribution is similar to that in November, although densities appear to be declining at some locations.  One species of vascular SAV, Vallisneria americana, continues to be present in low density at a few sites near the northern and western shoreline.  Water clarity in nearshore areas remains favorable for continued SAV growth (SD:TD ratio > 0.5).

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  Discharge at S-97 on the C-24 Canal averaged 1 cfs.  Discharge at S-49 on the C-23 canal averaged 0.3 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)

7.0 (7.6)

9.0 (9.1)

 

HR1 (N. Fork)

11.7 (9.5 )

14.4 (12.8)

 

Roosevelt Bridge

14.8 (13.3)

15.7 (13.7)

8.0 – 25.0

A1A Bridge

23.6 (21.4)

26.8 (26.4)

20.0 – 31.0

 

Salinity increased this week at most monitoring sites.  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 147 mg/l.  Average salinity increased at most monitoring sites over the past week.  Shell Point was not reporting.  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)

14.8 (13.6)

15.6 (14.4)

Rt. 31 Bridge

14.5 (13.8)

16.4 (16.1)

I-75 Bridge

14.1 (14.0)

16.9 (17.0)

Ft. Myers Yacht Basin

20.3 (19.1)

20.4 (20.2)

Cape Coral Bridge

25.6 (24.0)

27.7 (27.2)

Shell Point

NA (32.5)

NA (34.1)

 

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

 

FWRI reports that water samples collected this week detected background to low concentrations of Karenia brevis, the Florida red tide organism, along the coast of Collier County and 11 to 14 miles north of Key West (Monroe County).  Additional offshore samples, collected 12 miles west of Siesta Key (Sarasota County), contained background to very low concentrations of K. brevis.  Background concentrations were also detected in Pinellas County at Pier 60 on Clearwater Beach.  No reports of fish kills have been received from southwest Florida.

 

Water Conservation Areas

 

Excellent (for wading birds) dry season recession rates continue to dominate the entire region.  Only two regions did not conform to the general weekly recession pattern of -0.05 ft to -0.16 ft; WCA-3B, where seepage out of WCA-3A appears to be keeping 3B hydrated, and the center of 2B, where recession rates are too high because marsh water has a tendency to easily drain to the East.  Although recession rates are GOOD, the depths in the Everglades remain too deep for wading bird foraging.  This is normally not an issue at this time of year because foraging in support of nesting behavior does not usually begin until February.  Only the NW corner of WCA-3A has proper depths and recession rates to support wading birds.  However, it is unknown if birds are using this area and if fish for prey are available (Fish may not have yet recovered from the current drought).  Stages in WCA-1 and WCA-3 are below regulation and WCA-2A remains about one foot above regulation.

 

Everglades National Park

 

Another week of light rainfall brought declining water levels across Everglades National Park (ENP) wetlands.  Water level in Shark River Slough (at P33) was down by nearly 0.06 ft (following several weeks of little change).  In the southern part of the system, water level declined by 0.07 ft at Craighead Pond.  Stage was also down in the panhandle by 0.06 ft.  Taylor Sl. Bridge saw water level drop by nearly 0.19 ft last week (not unusual for this time of year).

 

Salinity remained stable across Florida Bay last week.  In the Taylor River ponds salinity remained below 1 psu over the entire week.  In the north-central Bay areas, Terrapin Bay and McCormick Creek remained very low all week (8 – 13 psu).  In central Florida Bay, Whipray Basin salinity held just below 30 psu for another week.  In the SRS outflow at Tarpon Bay, salinity decreased slightly to 4 psu by Sunday, 12/9.  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 Lower East Coast are still slightly above their historical averages – although many wells recorded modest declines in the past week.  Water levels in the Upper East Coast continue to remain above their historic 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 147 ppm – slightly above the concentration recorded last week - and the plant has now resumed operations.

 

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