MEMORANDUM
TO: Chip
Merriam, Deputy Executive Director, Water Resources
FROM: SFWMD Staff Environmental Advisory Team
DATE: February 26, 2008
SUBJECT: Weekly
Environmental Recommendation for Systems Operations
Recommendation
No Lake Okeechobee regulatory releases to the
south or estuaries are recommended.
Background
Some showers
and thunderstorms. Moisture is beginning to return
to the area ahead of an approaching cold front.
Expect the front to move into north central Florida
by sunset, Lake Okeechobee after midnight, and
then be near the southern end of the District Wednesday morning. Afternoon heating will generate some
scattered showers activity over the interior and east today and then stronger
thunderstorm activity will move into northern areas with the front this
evening. As the front moves southward
overnight, shower coverage and intensity will decrease. Scattered shower activity will persist south
Wednesday morning, then dry conditions will move over
the District and persist the remainder of the week. Another cold front is expected to bring
another round of rain next Tuesday. 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 0.37 inches of rainfall to raise the 117-day total to 4.96 inches
(51% of average) and the lower basin received 0.58 inches to raise the 117-day
total to 4.42 inches (57% of average). 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 900 cfs
are being made from Lake
Toho (S-61) and of 200 cfs from East Lake Toho to allow a more gradual water level
recession during the snail kite nesting season. No other releases are being made in the upper
basin.
In
the upper basin, snail kites continue to nest on East Lake Toho and Lake Toho. Several additional nests have been reported
in Lake Toho. A whooping crane nest with eggs has been
reported on Lake Kissimmee. Flow has been
reestablished to the Kissimmee River for 216
days (S-65 re-opened on 07/18/07). Dissolved
oxygen concentrations in the river channel of the Kissimmee
River ranged from 5.5 mg/L to 8.6 mg/L with an average of 7.3
mg/L.
Lake Okeechobee
According
to the USACE web site, Lake
Okeechobee stage is 10.13’ NGVD, which
is the same as a week ago and 0.03’ higher than a month ago. The current stage is 1.15’ lower than it was
a year ago and 4.48’ below its historical average for this time of year. Reported inflows cfs
include the Kissimmee
River (~250 cfs), the S77 (~150 cfs),
and the L8 at Canal Point (~600 cfs). No outflows are reported.
Monthly
phytoplankton bloom monitoring was conducted on Monday February 25. Six of nine sites had sufficient water to
access for sampling. No blooms were
observed. Water clarity was typical for
this time of year with secchi depths ranging from
0.20-0.75 m. Average secchi depth was 0.50,
which is the highest value for February since before the hurricanes in 2004.
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)
|
10.6 (9.7)
|
13.1 (12.7)
|
|
HR1 (N. Fork)
|
15.9 (16.9)
|
18.2 (18.2)
|
|
Roosevelt Bridge
|
21.3 (21.2)
|
21.7 (22.0)
|
8.0 – 25.0
|
A1A Bridge
|
27.1 (27.6)
|
28.5 (28.7)
|
20.0 – 31.0
|
Average
salinity changed very little (< 1.0 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 21.3 ppt at
the Roosevelt Bridge is 6.7 ppt
below the maximum weekly average of 28.0 ppt achieved
in May 2001 during the 2000 – 2001 drought.
Caloosahatchee Estuary
Discharge
at S-79 averaged 55 cfs for the week, down from
previous week’s 150 cfs. The 30-day average is 78 cfs.
Freshwater flow back into the Lake from C-43,
through S-77, averaged 156 cfs during the last
week. The concentration of chlorides at
the Olga Plant were stable during the last week , with
171 mg/l reported last Sunday. In
general, average salinity declined over the past week, most notably at Ft. Myers
and upstream, with the largest change of about 2.0 ppt
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)
|
14.2 (16.7)
|
14.5 (16.5)
|
Rt.
31 Bridge
|
15.1 (16.8)
|
17.1 (19.0 )
|
I-75
Bridge
|
NA (NA)
|
18.6 (20.2)
|
Ft. Myers
Yacht Basin
|
22.5 (23.6)
|
22.5 (23.8)
|
Cape Coral Bridge
|
27.1 (26.9)
|
30.4 (30.7)
|
Shell
Point
|
34.2 (34.2)
|
35.6 (35.5)
|
Salinity
at the Ft. Myers surface sensor remains above the
1-day MFL maximum criterion of 20 ppt. The current surface salinity of 14.2 ppt at S-79 is 5.8 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.
However, salinity for seagrass in the area downstream
of Cape Coral
sensor is good.
In
summary, conditions in the upper estuary east of Ft. Myers
are poor due to high salinity. Based on
the tolerances of oysters, salinity 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
Dry season
recession rates were mixed in the Greater Everglades. After last week’s reversals, most of the
recession rates returned to good or fair, although rapid reversals of 0.31’ in WCA-2A and 0.19’ at Stage 63 in northern WCA-3A represent poor dry season events. After the previous week’s heavy rainfalls,
water depths in most of the conservation areas rose to levels too deep for
foraging (deeper than 1’), particularly in WCA-1, 2,
and southern WCA-3A (with poor depth ratings). Water depths in northern WCA-3A
and southern WCA-3B are the exceptions, with a rating
of good (0.1’-0.8’). Water depths range
from 0.4’ to 2.0’ at all reporting gauges.
Stages in WCA-1 and WCA-3
are about at regulation, while the WCA-2A marsh has
risen higher above regulation than it was last week
Everglades National
Park
Rainfall
was patchy last week across Everglades National Park (ENP)
and Florida Bay.
Marine and wetland platforms in ENP recorded
between 0”–1.0” of precipitation. The ENP basin spatially-averaged RAINDAR
similarly reflects this total at 0.13”.
Last
week’s water level trends for ENP wetlands were
mixed. Shark River Slough (station P33)
and southern Taylor Slough (at Craighead Pond) water levels declined by 0.8”
and 2”, respectively, for the week.
Water depths rose nearly 0.5” in the ENP
panhandle (station EVER6). Stages rose through the early part of last
week at Craighead Pond, ending up at just 0.1” weekly increase.
Salinity
concentrations remained generally stable again in Florida Bay
last week. Salinity remained in the mid-
to upper 20s at Trout Creek. At the
mouth of Taylor River, salinity remained just above 20 psu for another week.
Salinity concentrations in the Taylor ponds remained in the single
digits last week; the 30 day moving average concentration at Argyle Hendry
(station TR, used to track FL Bay MFL
criterion) was at 7.4 psu as of Sunday, 2/24. Salinity concentrations were in the low to mid-20s last week at Little Madeira Bay and in the
north-central Bay areas of McCormick Creek and Terrapin Bay.
Whipray
Basin salinity remained near
33 psu throughout the week. As a whole these salinity concentrations are
still near seasonal norms. The exception
to this trend is out west, in the Shark River Slough outflow at Tarpon Bay,
where salinity still remains above its seasonal average, measuring near 15 psu as of Sunday 2/24; 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 remain slightly 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 well 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 and continue to rebound as a result of recent 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.
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 171 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