MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       February 19, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Minor rains south and east today and tomorrow.  A frontal boundary is exiting southward through the Keys this morning while a batch of mainly light rain slides eastward across south Florida.  Look for this rain to exit south and east at lunch time with little rain expected this afternoon through tomorrow morning.  The front will begin to return northward as a warm front tomorrow evening as the next upstream weather system moves into eastern Texas.  The warm front should generate some showers mainly east tomorrow night/predawn Thursday, then a higher coverage of showers mainly north of the Lake on Thursday.  Little or no rain is expected Friday before showers/storms focus north of the Lake on Saturday.  The next ten days precipitation outlook is near average with moderate confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received approximately 0.4-0.5 inches of rainfall and the lower basin received 1-1.5 inches of rainfall. Water levels in the upper basin lakes are at or below their regulation schedules.

 

Lake Kissimmee (S-65) continued discharging approximately 250 cfs to the Kissimmee River.  Releases of 300 cfs are being made from Lake Toho (S-61).  No other releases are being made in the upper basin.  In the upper basin, snail kites are nesting on East Lake Toho in addition to Lake Toho.

 

Flow has been reestablished to the Kissimmee River for 209 days (S-65 re-opened on 07/18/07).  Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 5.1 mg/L to 8.9 mg/L with an average of 7.2 mg/L.

 

The USFWS has requested to begin making releases now from Lake Toho and East Lake Toho so that the water levels in these lakes would decrease more gradually to the low pool stage of the regulation schedule by June 1.  Earlier releases and a slower recession rate are thought to benefit the endangered snail kite during its nesting season.  This should also result in lower discharges for hydrilla treatment in Lake Cypress.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.13’ NGVD, which is 0.15’ higher than a week ago and 0.04’ lower than a month ago.  The current stage is 1.18’ lower than it was a year ago and 4.64’ below its historical average for this time of year.  Reported inflows include the Kissimmee River, the S77, and the L8.  No outflows are reported.

The February submerged-aquatic-vegetation (SAV) survey is complete.  The macroalga Chara remains the dominant SAV species and was found at 8 of the 29 sites sampled.  This distribution is similar to that reported in January.  Total biomass increased slightly from 0.21 g dw/m2 in January to 0.46 g dw/m2 in February.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  No discharge occurred at S-97 on the C-23 Canal or at S-49 on the C-24 canal.  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)

9.7 (12.9)

12.7 (15.6)

 

HR1 (N. Fork)

16.9 (16.4)

18.2 (18.7)

 

Roosevelt Bridge

21.2 (22.0)

22.0 (22.5)

8.0 – 25.0

A1A Bridge

27.6 (28.0)

28.7 (28.9)

20.0 – 31.0

 

Average salinity decreased by several ppt at the Palm City Bridge during the past week but fell only slightly (< 1.0 ppt) at most other 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.  The current surface salinity of 21.2 ppt at the Roosevelt Bridge is 6.8 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

 

Caloosahatchee Estuary

 

Owing to local rainfall, discharge at S-79 occurred from Feb 15 to Feb 18 and averaged 150 cfs for the week.  The concentration of chlorides at the Olga Plant is 180 mg/l.  In general, average salinity declined over the past week, with the largest changes occurring near S-79 where discharges occurred.  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)

16.7 (17.6)

16.5 (17.7)

Rt. 31 Bridge

16.8 (18.1)

19.0 (19.8 )

I-75 Bridge

NA (NA)

20.2 (21.2)

Ft. Myers Yacht Basin

23.6 (23.9)

23.8 (23.8)

Cape Coral Bridge

26.9 (27.1)

30.7 (30.8)

Shell Point

34.2 (34.3)

35.5 (35.4)

 

Salinity at the Ft. Myers surface sensor remains above the 1-day MFL criterion of 20 ppt.  The current surface salinity of 16.7 ppt at S-79 is 3.3 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 near (surface) or above (bottom) the upper limit of the optimal range for the oyster, Crassostrea virginica.  Conditions in the upper estuary east of Ft. Myers are poor due to high salinity.  Based on the salinity tolerances of oysters conditions downstream of Cape Coral are fair.

FWRI reports that no Karenia brevis, the Florida red tide organism, was detected this week in water samples collected alongshore between Pinellas and Collier counties.

 

Water Conservation Areas

 

Poor dry-season recession rates dominate the entire region.  Reversals dominate everywhere due to the heavy rain.  Maximum increase in stage was 0.43 ft at gauge 63 (NE WCA-3A).  Minimum stage increase was 0.09 ft at Gauge 76 (northern WCA-3B).  Despite the reversals, the water depth criteria for water bird foraging remained much the same as last week.  Stages in WCA-1 are now above Regulation, WCA-2A marsh remains above regulation (note: canal levels dropped sharply due the opening of the S-11’s), and WCA-3 stages are now only slightly below regulation.  Stages are now greater than they were a month ago.

 

Everglades National Park

 

Everglades National Park (ENP) wetland water levels increased in response to this precipitation.  Shark River Slough (station P33) and southern Taylor Slough. (at Craighead Pond) both posted water levels up by approximately 1 inch from last week’s readings.  The most significant rise was observed at the Taylor Slough Bridge, where it increased by nearly 14 inches over the seven day period.  Stage increased by a more modest amount (0.4”) in the ENP panhandle (station EVER6) where less rain was recorded.

 

Despite the rain, salinity concentrations remained generally stable in Florida Bay.  Salinity held in the mid-upper 20s at Trout Creek.  At the mouth of Taylor River salinity read just above 20 psu for another week.  Salinity concentrations in the Taylor ponds were in the teens for much of the week before dropping into single digits over the weekend; the 30 day moving average concentration at Argyle Hendry (station TR, used to track Florida Bay MFL criterion) was at 7.2 psu as of Sunday, 2/17.  Salinity concentrations were in the low-20s last week at Little Madeira Bay and in the north-central Bay areas of McCormick Creek & Terrapin Bay.  Whipray Basin remained just over 33 psu as of Sunday, 2/17.  As a whole these salinity concentrations are still near seasonal norms.  The exception to this trend is out west, in the SRS outflow at Tarpon Bay, where salinity remains above its seasonal average, measuring near 15 psu as of Sunday 2/17.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast increased slightly this past week, and remain below their historical average conditions for this time of year.  Water levels in the Lower East Coast are still near or slightly above their historical averages and most wells recorded modest increases in water levels this past week.  Water levels in the Upper East Coast remain above their historic averages.  Surface and groundwater levels in Water Conservation Areas 1 and 2 are now near their historic averages as a result of local rainfall.  Water levels in WCA 3A continue to remain below their historic averages and were somewhat lower this week.  Water levels in the southernmost portion of Miami-Dade County are now below average historic conditions.

 

Six out of eleven water supply risk measures are in the “high” risk category including the projected Lake Okeechobee Stage (SSM), the Palmer Index for Tributary Conditions, the CPC Precipitation Outlook, and Lower East Coast Service Areas 1, 2 and 3.

 

The LOK Seasonal Net Inflow and the LOK Multi-Seasonal Net Inflow Forecasts remain at “medium” risk this week.  Water Conservation Areas 1, 2A and 3A continue to be in the “low” risk category.

 

Chlorides at the Olga WTP on the Caloosahatchee River are now at 180 ppm and the plant is operational.

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake Okeechobee 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 Niña climactic conditions.

 

 

 

 

 

 

 

 

 

 

CC:   George Horne