M E M O R A N D U M

 

TO:             Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:       SFWMD Staff Environmental Advisory Team

 

DATE:                 June 10, 2008

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Scattered showers and some strong storms focused north and east today.  An upper level low near Tampa has cooled/destabilized the atmosphere.  Associated steering winds have switched to the south and southwest, which should allow more moisture to move up over the peninsula as well.  Under this environment, look for seabreeze processes to force a good crop of afternoon thunderstorms.  Storms will move faster south of the Lake, so this should limit local rainfall there.  Steering flow weakens Wednesday while the upper low begins to exit eastward.  Models leave good moisture over the area though, so look for a minor decrease in activity tomorrow afternoon.  Storms should focus south on Thursday before beginning a pronounced decrease Friday and Saturday as drier air comes in from the east.  The next ten days precipitation outlook is below average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 1.17 inches of rainfall to bring the 30 day total to 2.45 inches (54% of average), and the lower basin received 0.65 inches to bring the 30 day total to 1.84 inches (40% of average).

 

The spring recession of the regulation schedule has ended in the upper basin lakes.  Consequently, releases have ended from all lakes except for minimal releases from Lake Kissimmee for the Kissimmee River.  All upper Kissimmee Basin lakes are below regulation schedule.  In the upper basin, snail kites continue to nest on East Lake Toho, Lake Toho, and Lake Kissimmee.  Nests on Lake Toho continue to represent a large fraction of the total number of snail kite nests in Florida.

 

Flow has been reestablished to the Kissimmee River for 321 days (S-65 re-opened on 07/18/07).  Flow is approximately 180 cfs at S65 and 140 cfs at S-65C.   Much of the floodplain within the area of the Kissimmee River Restoration Project is dry except for isolated pools.  These pools continue to attract foraging wading birds.  The water level in the area of the restoration project decreases by 0.3 feet from 33.6 feet near the upstream end (station PC62) to 33.3 feet at the downstream end (headwater stage at S-65C).

 

Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 1.9 mg/L to 8.6 mg/L with an average of 6.4 mg/L. The value below 2 mg/L was for a single measurement.


Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.35’ NGVD, which is 0.20’ lower than a week ago and 0.72’ lower than a month ago. The current stage is 0.37’ higher than it was a year ago and 3.07’ below its historical average for this time of year. No inflows are reported. Outflows include 660 cfs through the S351 and 440 cfs through the S354.

 

The monthly Submerged Aquatic Vegetation (SAV) survey is underway.  Water transparency is excellent at the south end of the lake and the macroalga Chara is spreading rapidly but vascular SAV remains absent.  Chara is also expanding near Clewiston and north of Cochran’s Pass.  Transparency is also good along the western shoreline, where beds of Vallisneria continue to expand.  The northern shoreline will be surveyed for SAV today.

 

An apple snail egg survey was conducted in the littoral zone during the last week of May.  Ten clusters were found in the vicinity of Indian Prairie in the northwest marsh.  This is the same location where egg clusters were found during an identical survey in April.  Findings to date indicate that the continued drought has eliminated apple snails across most of the littoral zone.

 

Wildfires continue to burn in the lake’s littoral zone but are not expanding primarily due to a lack of fuel.

 

St. Lucie Estuary

 

There were no releases through S-80 from C-44, S-48 from C-23, and S-49 from C-24 over the past week.  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)

18.06 (16.64)

20.11 (18.88)

 

HR1 (N. Fork)

20.92 (21.40)

22.16 (21.98)

 

Roosevelt Bridge

23.72 (23.48)

24.43 (24.27)

8.0 – 25.0

A1A Bridge

29.82 (29.56)

30.31 (30.67)

20.0 – 31.0

 

Compared with salinities of the previous week, average salinity increased by 2 ppt at Palm City Bridge and stayed about the same at Roosevelt Bridge (about 24 ppt), A1A Bridge (about 30 ppt), and HR1 (about 21 ppt).  The salinities at both Roosevelt and A1A Bridge are just within the upper limit of the preferred range.  Salinity conditions in the estuary are considered fair, based on the salinity preference of the oyster, Crassostrea virginica, at Roosevelt Bridge.  The current surface salinity of 23.7 ppt at the Roosevelt Bridge is 4.3 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

 

Caloosahatchee Estuary

 

No discharge occurred through S-79 during the past week.  An average weekly discharge of 227 cfs occurred at S-77 through Sunday.   On Monday 14 cfs went back into Lake Okeechobee.  An average weekly discharge of 21.6 cfs occurred at S-78.  The concentration of chlorides at the Olga Plant was 232 ppm yesterday, down from 249 ppm in the beginning of this reporting period.

 

Due to technical difficulties, salinity readings from the six stations in the Caloosahatchee Estuary are not accessible at this point.  Coordination is ongoing with the District IT staff to solve the problem.  Average salinities of the previous week were provided in parenthesis.  Based on local hydrologic conditions and salinity data collected by other agencies, it can be reasonably assumed that salinity conditions in the Caloosahatchee Estuary remain similar to that in the previous week.  Salinity data collected by both USGS (Marker 52,  and Sanibel-Captiva Conservation Foundation indicate that average salinity from June 3 to 10 at Ft. Myers was about 26-27 ppt, similar to that of the previous week.  This is about 6-7 ppt above the 1-day MFL criterion of 20 ppt.  Salinity at Shell Point monitored by Sanibel-Captiva Conservation Foundation was about 36 to 38 ppt during the past week.

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

NA ( 19.49)

NA (20.85)

Rt. 31 Bridge

NA (19.47)

NA (21.58)

I-75 Bridge

NA (20.28)

NA (22.67)

Ft. Myers Yacht Basin

NA (26.48)

NA (27.23)

Cape Coral Bridge

NA (31.74)

NA (31.95)

Shell Point

NA (35.88)

NA (36.60)

 

In summary, salinity conditions in the upper estuary east of Ft. Myers are still poor due to high salinity.  Conditions in the lower estuary downstream of Cape Coral are becoming poor considering the combine salinity preference of oysters and seagrasses.

 

No Karenia brevis, the Florida red tide organism, was detected this week in the water samples collected alongshore between PinellasCounty and the Florida Keys or offshore of Pinellas, Manatee, Sarasota, or Monroe counties.  Discolored water has been reported nearshore in Lee, Collier, and Monroe counties due to the presence of high concentrations of the marine cyanobacterium Trichodesmium.  Trichodesmium can collect at the water surface and appear brown, green, or white.  At high concentrations, a Trichodesmium bloom may be mistaken for an oil or sewage spill.

 

Water Conservation Areas

 

Stages are declining throughout the WCA’s.  Although it is the beginning of the rainy season, good recession rates and water depths exist in the Everglades for wading bird foraging.  Water depths are generally between 0.5’ and 1.0’ except for WCA-2A (0.26’) and WCA-2B (1.19’).  Stages are currently slightly above regulation in WCA-1, above regulations in WCA-2A, and slightly below regulation in WCA-3A.

 

Everglades National Park

 

Rainfall was patchy across Everglades National Park (ENP) and Florida Bay last week with heavier rains toward the central and western areas of ENP.  The 7 day accumulations for wetland and marine stations measured between 0.02 – 1.8” and 0 – 1.1”, respectively.  The basin-wide spatially-averaged weekly RAINDAR totals were 1.3” in the ENP basin and 0.4” in the C-111 basin.

 

In response to the spatial pattern of rainfall, ENP wetland water levels were relatively stable or dropped slightly last week.  The water level was unchanged at SRS (station P33) and increased slightly by 0.1” in the panhandle (station EVER6) over the week.  To the east, water level saw declines of 1.8” at Taylor Slough Bridge (not an unusual recession rate at this station) and 0.2” south at Craighead Pond.

 

Salinity in Florida Bay generally increased as result of persisting low rainfall and high evaporation.
Concentrations increased slightly, remaining in the middle to upper 30s across most of northeast Florida Bay.  In the Taylor Ponds, salinity continued to climb for another week, reaching the upper 30s at Pond 5 (USGS station) and Argyle Hendry (ENP station TR).  As of Sunday, 6/8, the 30 day moving average concentration at Taylor River (used for tracking the Florida Bay MFL criterion) was at 33.5 psu, up from 32.1 psu last week.  In the north central Bay areas, salinity increased through mid-week into the upper 40s before dropping back into the low 40s by week’s end in McCormick Creek, yet remained elevated in the upper 40s in Terrapin Bay.  Exceptions to the upward trend in salinity were seen at the central Bay station in Whipray Basin where salinity decreased slightly but remained in the mid 40s.  Additionally to the west in Shark River Slough (Tarpon Bay platform), salinity decreased slightly but remained in the middle to upper teens.

 

Water Supply

 

Although there was some scattered rain last week, most water levels decreased across most of the District.  Water levels in the upper and lower Kissimmee Basin are now well below their average conditions for this time of year and approaching their historic lows.  Water levels in the Lower West Coast are now below historical averages, though water level conditions depend on the degree of confinement of the aquifers.  Water levels in the Lower East Coast are near or slightly below their historical averages.  Water levels in the Upper East Coast are still slightly above their historic averages although they also have been declining.  Surface and groundwater levels in Water Conservation Areas 1, 2 and 3 are now near their historic averages although they have been declining over the past few weeks.  Water levels in the southernmost portion of Miami-Dade County are now significantly below their average historic conditions.

 

There were some changes (deterioration) in the water supply risk indicators since last week.  Five out of the eleven water supply risk indicator parameters are now in the “low” risk category, including the CPC Precipitation Outlook, the Lake Okeechobee Seasonal and Multi-seasonal Net Inflow Forecast, and Water Conservation Areas 1 and 3A.

 

Three out the eleven water supply risk indicators are now in the “medium” risk category, including LEC Service Areas 1, 2 and 3.

 

Three risk measures are now in the “high” risk category - the projected Lake Okeechobee Stage (Water Shortage Management Band), Palmer Index for Tributary Conditions (Very Dry) and WCA 2A.

 

LORS2008 (Lake Okeechobee Regulation Schedule)

 

The current Lake Okeechobee stage remains in the Water Shortage Management zone and is unlikely to move back into the Operational Band in the next several months during the persistent La Niña climactic conditions.

 

CC:   George Horne