MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       January 22, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Some showers mainly south today, then interior tomorrow.  Decent moisture exists over south this morning with isolated showers.  Look for these showers to increase some this afternoon as a weak upper level impulse moves through.  A rumble or two of thunder might even be heard.  Steering winds change tomorrow, and showers should pull northward and form more over the interior.  A weak cold front will push through on Thursday with a few more showers before cooler and dry weather returns Friday and Saturday.  The next ten days precipitation outlook is below average with low confidence.

 

Kissimmee Watershed

 

The seven day raindar rainfall estimates indicate about 1.5 inches of rainfall over the upper basin and 0.5 inches over the lower basin for the time period 1/15/08 – 1/22/08.  With the recent rainfall, water levels in the upper basin lakes rose slightly, approximately 0.1 feet.  Water levels in the upper basin lakes are below regulation schedules except for Lake Toho, which is at the 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 181 days (S-65 re-opened on 07/18/07).

 

In the river channel of the Kissimmee River, the concentration of dissolved oxygen ranged from 3.5 mg/L to 5.6 mg/L (mean 4.3 mg/L) for the last seven days.  Last week, a small algal bloom was observed in Pool C and D.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.11’ NGVD, which is 0.02’ higher than a week ago and 0.14’ lower than a month ago.  The current stage is 1.77’ lower than it was a year ago and 4.66’ below its historical average for this time of year.  Inflows from the Kissimmee River (S65E) continue at approximately 250 cfs.  No outflows are reported.

 

Results of the January monthly submerged-aquatic-vegetation (SAV) survey showed a decrease in average SAV biomass to 0.21 g DW m-2 from 2.31 g DW m-2 in December.  A normal seasonal decline in the macroalga Chara is responsible for this pattern.  The area behind King’s Bar continues to be one of the few areas supporting a nascent vascular SAV community.  Vallisneria continues to be found there and Hydrilla was observed last week.  This area was relatively sheltered from the damaging effects of the 2004-2005 hurricanes.  Current water levels continue to favor the development of new areas of emergent vegetation, including spikerush and bulrush, along the outer edge of the marsh from Clewiston up to the mouth of the Kissimmee.  Under normal lake stages, these areas would be dominated by SAV.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  Discharge at S-97 on the C-23 Canal and at S-49 on the C-24 canal averaged < 1.0 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)

11.1 (9.4)

13.5 (12.3)

 

HR1 (N. Fork)

15.4 (13.2)

16.8 (15.5)

 

Roosevelt Bridge

18.7 (16.6)

17.9 (16.7)

8.0 – 25.0

A1A Bridge

27.6 (24.2)

28.9 (26.7)

20.0 – 31.0

 

Average salinity increased during the past week.  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.  The current surface salinity of 18.7 ppt at the Roosevelt Bridge is 9.3 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

 

FWRI reports that concentrations of Karenia brevis, the Florida red tide organism, in samples collected between Volusia and St. Lucie counties ranged from not present to background.

 

Caloosahatchee Estuary

 

No discharge occurred at S-79 last week.   The concentration of chlorides at the Olga Plant is 182 mg/l.  Average salinity changed little over the past 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)

18.5 (18.7)

18.7 (18.7)

Rt. 31 Bridge

17.7 (17.4)

18.4 (19.1)

I-75 Bridge

(NA)

20.5 (21.8)

Ft. Myers Yacht Basin

22.7 (23.0)

22.9 (24.0)

Cape Coral Bridge

25.9 (25.7)

29.1 (29.0)

Shell Point

32.8 (33.7)

34.5 (35.5)

 

Conditions in the upper estuary east of Ft. Myers are poor due to high salinity.  The current surface salinity of 18.5 ppt at S-79 is 1.5 ppt below the maximum weekly average of 20.0 ppt achieved in May 2001 during the 2000 – 2001 drought.  Salinity at the Cape Coral Bridge is at the upper limit of the optimal range for the oyster, Crassostrea virginica.

 

FWRI reports that water samples collected between Pasco and Collier counties contained concentrations of Karenia brevis, the Florida red tide organism, ranging from not present to background.

 

 

Water Conservation Areas

 

Good dry-season recession rates continue to dominate the region.  WCA-3B was the only area where recession rates were poor due to little change over of the last few weeks.  This should not set off any alarms and desires to decrease WCA-3B water levels at this time because water levels are below average for this time of year.  Stages in WCA-1 are below Regulation, WCA-3 stages continue to be significantly below regulation, and WCA-2A remains above regulation.

 

Everglades National Park

 

Everglades National Park (ENP) wetland water levels continue to decline.  Taylor Slough Bridge saw the most substantial weekly drop of nearly 1.6”, which is not unusual for this station.  Water level in Shark River Slough (station P33) declined by 0.6” over the week.  Stage in both of these areas remains well below average for this time year (compared to the previous decadal average), off by 1.25’ at TSB & by 0.75’ at P33.

 

Salinity concentrations decreased slightly or remained stable in Florida Bay (FL Bay) last week.  The 30 day moving average concentration at Taylor Ridge (used for to monitor exceedances to the FL Bay MFL rule) is still low at close to 3 psu.  In the SRS outflow at Tarpon Bay, salinity measured 12.5 psu as of Sunday 1/20, above average for this time of year (typically concentrations remain in the single digits until much later in the dry season); this is not surprising given the low water levels in SRS.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast continued to decline 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 below 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 now below average historic conditions.

 

Seven 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 CPC Precipitation Outlook, 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 and the LOK Multi-Seasonal Net Inflow Forecasts remain at “medium” risk this week.

 

Chlorides at the Olga WTP on the Caloosahatchee River are now at 182 ppm and the plant is operational.

 

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 during the persistent La Nina climactic conditions.

 

 

 

CC:   George Horne