MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       February 5, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Some rains developing north to south Thursday through Saturday.  High pressure will hang on through tomorrow afternoon before an upper level trough and attendant cold front slide slowly through the peninsula.  Look for some showers to focus north of the Lake late Thursday and around the Lake on Friday, then minor rains south Saturday before a secondary surge shoves drier and cooler air down the peninsula by Sunday.  Subsequent hope for rains arrives in 8-9 days.  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 2.99 inches, which was 128% of the long term average, and the lower basin received 0 inches to bring the 30-day total to 1.04 inches, which was 56% of average.  Water levels in the upper basin lakes appear to have stabilized from rainfall in recent weeks.  Water levels are at or below regulation schedules for respective lakes.

 

Lake Kissimmee (S-65) continued discharging approximately 250 cfs to the Kissimmee River. Releases from Lake Toho (S-61) have decreased from 700 cfs to 0 cfs.  No other releases are being made in the upper basin.  Flow has been reestablished to the Kissimmee River for 195 days (S-65 re-opened on 07/18/07).  Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 6 mg/L to 8.1 mg/L with an average of 8.1 mg/L.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.05’ NGVD, which is 0.01’ lower than a week ago and 0.07’ lower than a month ago.  The current stage is 1.53’ lower than it was a year ago and 4.66’ below its historical average for this time of year.  The lake continues to receive inflows of approximately 250 cfs from the Kissimmee River (S65E).  No major outflows are reported.

 

Monthly submerged aquatic vegetation (SAV) monitoring is being performed this week.  Initial reports from the south end of the lake are that water clarity is excellent but SAV is sparse and limited to the macroalga Chara.  The January water-quality monitoring trip was performed on the 29th but data from that trip are not yet available.

 


St. Lucie Estuary

 

There were no releases through S-80 from Lake Okeechobee or the C-44 Basin.  There was no discharge from S-49 on the C-24 Canal during the last week and average flow for the week from C-23 through S-97 was not available.  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 (South Fork)

11.75 (11.2)

15.53 (14.2)

 

HR1 (North Fork)

16.53 (16.5)

19.01 (18.27)

 

Roosevelt Bridge

19.51  (19.2)

20.51 (20.2)

8.0 – 25.0

A1A Bridge

25.70 (27.3)

27.27 (28.7)

20.0 – 31.0

 

Except at the A1A Bridge, average salinity increased slightly during the past week.  Both the surface and bottom salinity are in the preferred range at the Roosevelt Bridge, and at the A1A Bridge.  The current surface salinity of 19.51 ppt at the Roosevelt Bridge is 8.5 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought (last week’s difference was 8.8 ppt).  Based on the salinity tolerances of the oyster, Crassostrea virginica, salinity conditions in the estuary are good.

 

FWRI reports that no water samples were collected this week from the east coast of Florida.

 

Caloosahatchee Estuary

 

There were no releases through S-79 from Lake Okeechobee.  The 30-day average discharge from S-79 is 86 cfs.  The concentration of chlorides at the Olga Plant is 180 mg/l.  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)

17.03 (16.9)

17.63 (17.8)

Rt. 31 Bridge

17.29 (17.7)

20.05 (19.5)

I-75 Bridge

NA

21.10 (20.5)

Ft. Myers Yacht Basin

23.95 (23.6)

24.24 (23.6)

Cape Coral Bridge

26.15 (25.3)

30.82 (30.3)

Shell Point

34.48 (33.8)

35.86 (35.3)

 

The salinity at all the recorders slightly increased with the exception of the bottom salinity at S79 and the surface salinity at Rt. 31 Bridge.  The current surface salinity of 17.03 ppt at S-79 is 2.97 ppt below the maximum weekly average of 20.0 ppt achieved in May 2001 during the 2000 – 2001 drought.  Salinity at the Ft. Myers surface sensor remains above the 1 day MFL target (20 ppt).  Salinity at the Cape Coral Bridge surface recorder is at the upper limit of the optimal range for the oyster, Crassostrea virginica.  Salinity at the bottom sensor exceeds the preferred range. Salinity at Shell Point is either near or is beginning to exceed the tolerance limits of oysters. Salinity downstream of Cape Coral is good for seagrass.

 

Based on submerged plants requirements, conditions in the upper estuary, east of Ft. Myers, are poor due to high salinity.  Based on the salinity tolerances of oysters, salinity conditions in the estuary downstream of the Cape Coral Bridge is fair.

 

FWRI reports that water samples collected along the shore between Pinellas and Collier counties contained no Karenia brevis, the Florida red tide organism.

 

Water Conservation Areas

 

Good dry-season recession rates continue to dominate the region.  The only region with poor or fair recessions is North East Shark River Slough.  Here, the hydrology is in spatial discourse, such that one region has a recession rate that is too fast, while another region has a recession rate that is too slow.  And where, to make things even worse, good depths are not corresponding to good recession rates.  Regulation stages remain where they have been for the last few months.  Stages in WCA-1 are slightly below Regulation, WCA-2A remains above regulation, and WCA-3 stages continue to be significantly below regulation.

 

Everglades National Park

 

Everglades National Park (ENP) wetland water levels fell in response to this lack of precipitation.  Water level at Taylor Slough Bridge dropped by 1.2”, falling to 1.8’ below ground surface.  Shark River Slough. (station P33) and southern Taylor Slough. (at Craighead Pond) also posted declines of nearly 0.75” and 1”, respectively.  The ENP panhandle saw the smallest weekly decline of only 0.1” (likely a residual effect of higher rainfall totals in this area the week prior).

 

Salinity concentrations increased slightly or remained stable in Florida Bay for another week.  Salinity remained in the lower-mid 20s at Trout Creek.  At the mouth of Taylor River salinity read just above 20 psu for much of the week.  Data have been unavailable for the Argyle Hendry “TR” platform since 1/30, a report on the 30 day running average concentration for MFL tracking is not possible.  The platform at Whipray Basin recorded increasing salinity in the central Bay, up to near 32 psu as of Sunday, 2/3.  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 15 psu as of Sunday 2/3.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast increased on average this week, but 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 due to local rainfall.  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 Miami-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 Okeechobee 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.

 

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

 

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