MEMORANDUM
TO: Chip Merriam, Deputy Executive
Director, Water Resources
FROM: SFWMD
Staff Environmental Advisory Team
DATE: April 15, 2008
SUBJECT: Weekly Environmental
Recommendation for Systems Operations
Recommendation
No Lake Okeechobee regulatory releases to the south or
estuaries are recommended.
Background
Limited light shower activity.
A low pressure system currently located about 500 miles east of Melbourne is expected to
exit to the northeast by Thursday. Some
moisture and clouds are wrapping around the back side of this low and are
generating scattered showers near the east coast of Florida.
Expect breezy conditions with some of these showers affecting
northeastern portions of the District today.
High pressure will then build in behind this low bringing dry conditions
Thursday and Friday. The next cold front
will have limited moisture as it moves into north central Florida Saturday evening resulting in widely
scattered light showers Saturday night and Sunday. The next ten days precipitation outlook is below
average with moderate confidence.
Kissimmee Watershed
The 30 day rainfall total has increased to 4.20 inches (163% of
average). The large rainfall reported
last week resulted in stage reversals in several lakes in the upper basin. The largest reversal was 0.75 ft in Lake Toho,
which has the potential to impact on apple snail reproduction and nesting by
wading birds and snail kites. In the upper basin, snail
kites continue to nest on East Lake Toho, Lake
Toho, and Lake Kissimmee.
A whooping crane continues to nest on Lake Kissimmee. The discharge from
Lake Kissimmee
(S-65) continues at approximately 1500 cfs to provide
flow to the Kissimmee River and to allow a
gradual water level recession on the floodplain. No other releases are being made in the upper
basin. Flow has been reestablished to
the Kissimmee River for 265 days (S-65
re-opened on 07/18/07). The inflow from
the upper basin continues to inundate a portion of the floodplain in the Phase
I area of the Kissimmee River Restoration Project.
Dissolved
oxygen concentrations in the river channel of the Kissimmee
River ranged from 1.8 mg/L to 4.7 mg/L with an average of 3
mg/L. Hydrilla
treatment began in Lake
Cypress last week and
continues this week. It is anticipated
that releases from Lake
Toho will resume on
Thursday (April 17).
Lake Okeechobee
According
to the USACE web site, Lake
Okeechobee stage is 10.48’ NGVD, which
is the same as a week ago and 0.30’ higher than a month ago. The current stage is 0.41’ higher than it was
a year ago and 3.61’ below its historical average for this time of year. Total reported inflows exceed 4800 cfs and include the Kissimmee River (~1900 cfs), S71 and S72 (~130 cfs), S84
(~40 cfs), S91 (~2160 cfs),
and the L8 at Canal Point (~640 cfs). Although not reported, additional inflows
likely continue through the S77 as well.
No outflows are reported.
March
water-quality monitoring results are now available. Fifteen of the 25 monitoring stations had
sufficient water for sampling. Total P
averaged 141 ppb lake wide (compared to 152 ppb in February) and 81 ppb at near
shore stations (compared to 77 ppb in February). Total suspended solids (TSS)
averaged 33 ppm lake wide (compared to 54 ppm in February) and 25 ppm at
near shore stations (compared to 26 ppm in February).
The
monthly submerged-aquatic-vegetation (SAV) survey was
completed last week. Water clarity was
generally conducive to plant growth with secchi
depths greater than 50% of total depths at 26 of the 30 sites sampled. The macroalga Chara remains the dominant SAV
species and was found at 12 of the 30 sites. One species of vascular SAV,
Vallisneria americana,
continues to be present in very low density at a few sites around King’s Bar on
the northern shoreline and a few sites along the western shoreline. Potamogeton illinoensis
(pondweed) was observed in very low density along the western shoreline near Observation Island.
St. Lucie Estuary
There
were no releases through S-80 over the past week. Discharge of 103 cfs
occurred at S-97 on the C-23 canal and discharge at S-49 on the C-24 canal was
unavailable this week. The current
weekly average salinities at the four monitoring sites in the St. Lucie 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
|
Envelope
|
Palm City
Bridge (S. Fork)
|
10.13 ( 11.55)
|
10.41 (12.64)
|
|
HR1 (N. Fork)
|
9.19 (12.09)
|
13.40(13.45)
|
|
Roosevelt Bridge
|
13.08 (16.22)
|
15.03 (16.98)
|
8.0
– 25.0
|
A1A Bridge
|
23.60 (25.35)
|
27.52 (27.56)
|
20.0
– 31.0
|
During
the past week, average salinity decreased about 1-2 ppt
throughout the estuary. 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 13 ppt at the Roosevelt Bridge is 15 ppt
below the maximum weekly average of 28 ppt achieved
in May 2001 during the 2000 – 2001 drought.
Caloosahatchee Estuary
Discharge
of 364 cfs occurred at S-79 last week. Discharge from S-77 into Lake
Okeechobee averaged 393 cfs last
week. The concentration of chlorides at
the Olga Plant is 155 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)
|
9.03 (14.45)
|
9.60 (14.50)
|
Rt.
31 Bridge
|
9.39 (15.06)
|
9.58(16.15)
|
I-75
Bridge
|
NA
(NA)
|
16.04 (20.17)
|
Ft. Myers
Yacht Basin
|
19.95 (23.19)
|
21.16 (23.32)
|
Cape Coral Bridge
|
26.87 (28.06)
|
27.74 (28.77)
|
Shell
Point
|
33.44 (34.33)
|
34.25 (35.22)
|
Average
salinities decreased ~ 5 ppt in the upper estuary and
1 to 2 ppt in the lower estuary. Salinity at the Ft. Myers
surface sensor fell just below the 1-day MFL
criterion of 20 ppt.
The current surface salinity of 9 ppt at S-79
is 11 ppt below the maximum weekly average of 20 ppt achieved in May 2001 during the 2000 – 2001 drought. Salinity at
the Cape Coral Bridge is near 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.
Conditions downstream of Cape
Coral are fair considering the salinity tolerances of
oysters.
FWRI reports that a bloom of
the marine cyanobacteria Trichodsmium
was reported in the Pine Island Sound area of Lee County,
however no impacts have been reported.
Very low concentrations of Karenia brevis, the Florida
red tide organism, were detected this week alongshore of Sarasota
County and southern Collier County.
Water Conservation Areas
Recession rates were high in WCA-1 due
to the movement of water north to Lake Okeechobee, the water deficit, and the
movement of water south through the S-10’s. Continued recessions may bring the water
levels in WCA-1 below the one foot mark in time for
Ibis to attempt a late season nesting. For
the rest of the system water levels continue to stay level or actually
increase. This environment does not concentrate fish into shallow
sloughs, as prey for wading birds. Depths continue to be too high in the WCA’s for wading bird foraging. Stages in WCA-1
first increased and are now declining, and approaching the Regulation Schedule,
WCA-2A marsh remains well above regulation, and WCA-3A stages are slightly above the zone E1 of the
regulation schedule, for protection of the Cape Sable Seaside Sparrow.
Everglades National
Park
Everglades
National Park (ENP) wetland water levels showed mixed
trends last week, but were generally higher as a result of rainfall some 10
days ago. Water level climbed by nearly 1foot at Taylor
Slough Bridge. The southern part of Taylor Slough (at
Craighead Pond) also posted a weekly water level increase of 2.4”. To the north, in the Shark
River Slough. system, water level was up by
1.8” at station P33 over the week. Water
level in the panhandle (station EVER6) responding
differently to the rainfall, showing only a short increase before dropping back
by the week’s end to where it measured last Sunday (4/6, at 0.2’ below ground
surface). This may be a result of the
station’s proximity to the C-111 canal (acting to drain nearby wetlands in
which stage was higher than that in the canal just after the rain event).
Salinity
in Florida Bay declined in response to rain events
from over a week ago. In the Taylor ponds, salinity
fell to below 20 psu at both Pond 5 (USGS station) and Argyle Hendry (ENP
station TR). Salinity
also dropped a bit in the north-central Bay areas of McCormick Creek and Terrapin Bay, where concentrations fell towards
or just below 30 psu. Local rainfall helped salinity drop into the
lower-30s last week at the central Bay station in Whipray Basin, though it increased slightly to
35 psu by the weekend. These salinity concentrations across Florida Bay are near seasonal norms. The most notable change in salinity occurred
in the upstream reaches of Shark River (Tarpon Bay
platform), an area where salinity has remained very high for much of the dry
season: the daily mean measurement here dropped to 10.7 psu
as of Sunday, 4/13. While this is still
slightly above this area’s seasonal average, it marks a substantial decline
(last week concentrations were approaching 20 psu).
Water
Supply
Water
levels in the upper and lower Kissimmee
Basin are now near their
historical average conditions for this time of year. Water levels in the Lower
West Coast are a “mixed bag” of slightly higher and lower than
historical averages, depending on the degree of confinement of the
aquifers. Water levels in the Lower East Coast are near or slightly above their
historical averages and wells recorded modest increases or decreases, depending
on proximity to well-fields. Water
levels in the Upper East Coast remain well
above their historic averages. Surface
and groundwater levels in Water Conservation Areas 1 and 2 are now above their
historic averages as a result of local rainfall. Water levels in WCA
3A have rebounded to near their historic averages this week. Water levels in the southernmost portion of Miami-Dade County are now near their average
historic conditions.
There
was a modest improvement in the Water Supply Risk Indicators for this week,
with the Palmer Index for Lake Okeechobee
tributary conditions improving from medium to low risk. Four out of eleven risk measures are in the
“high” risk category including the projected Lake Okeechobee Stage (SSM), and Lower East Coast
service areas 1, 2 and 3. The Climate
Prediction Center Precipitation Outlook remains in the “medium” risk category.
The
Lake Okeechobee Seasonal and Multi-seasonal Net Inflow Forecast, and Water
Conservation Areas 1, 2A and 3A continue to be in the “low” risk category
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