MEMORANDUM
TO: Chip
Merriam, Deputy Executive Director, Water Resources
FROM: SFWMD Staff Environmental Advisory Team
DATE: March 4, 2008
SUBJECT: Weekly
Environmental Recommendation for Systems Operations
Recommendation
No Lake Okeechobee regulatory releases to the
south or estuaries are recommended.
Background
Some showers storms each day
through Friday. A weakening prefrontal
trough will push a line of generally decaying showers storms into the District
late today. Look for a focus west
through north of the Lake during the late
afternoon and evening. The associated
cold front will push south of the Lake and
stall Wednesday where it will provide a focus for more showers storms tomorrow
afternoon. The front will begin to
return northward in 48 hours leaving unsettled conditions with showers focusing
north on Thursday. The front will again
push southward on Friday with scattered showers storms focusing west through
north of the Lake before exiting southeast on
Saturday morning. Look for District
rains to average near an inch through this 120 hour window. 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 0.36 inches of rainfall to raise the 30-day total to 1.42 inches
(52% of average) and the lower basin received 0.02 inches to raise the 30-day
total to 2.09 inches (89% 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. A whooping crane continues to nest on Lake Kissimmee.
Flow has been reestablished to the Kissimmee
River for 223 days (S-65 re-opened on 07/18/07). Dissolved oxygen concentrations in the river
channel of the Kissimmee River ranged from 5.3
mg/L to 7.9 mg/L with an average of 6.9 mg/L.
Lake Okeechobee
According
to the USACE web site, Lake
Okeechobee stage is 10.07’ NGVD, which
is 0.06’ lower than 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 4.51’ below its historical average for this time of year. Reported inflows cfs
include the Kissimmee
River (~250 cfs), the S77 (~50 cfs),
and the L8 at Canal Point (~600 cfs). No outflows are reported.
The
District’s vegetation management group reports that the exotic water grass Luziola subintegra has
spread from its initial reported location at the mouth of Fisheating Bay and is now distributed broadly
across the bay. This species is
considered to be invasive and herbicide applications are being performed to
control its spread.
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)
|
13.11 (10.6)
|
14.36 (13.1)
|
|
HR1 (N. Fork)
|
16.85 (15.9)
|
18.51 (18.2)
|
|
Roosevelt Bridge
|
20.35 (21.3)
|
20.78 (21.7)
|
8.0 – 25.0
|
A1A Bridge
|
27.86 (27.1)
|
29.23 (28.5)
|
20.0 – 31.0
|
Average
salinity changed very little 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 20.35 ppt at
the Roosevelt Bridge is 7.65 ppt
below the maximum weekly average of 28.0 ppt achieved
in May 2001 during the 2000 – 2001 drought.
Caloosahatchee Estuary
There
were no releases through S-79 over the past week, down from previous week’s 55 cfs. The 30-day
average is 48 cfs.
Freshwater flow back into the Lake from
C-43, through S-77, averaged 53 cfs during the last
week. The concentration of chlorides at the Olga Plant were
stable during the last week, with 198 mg/l reported yesterday. Average salinity changed very little
throughout the estuary. 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)
|
14.46 (14.2)
|
15.26 (14.5)
|
Rt.
31 Bridge
|
14.36 (15.1)
|
16.81 (17.1 )
|
I-75
Bridge
|
NA (NA)
|
17.78 (18.6)
|
Ft. Myers
Yacht Basin
|
21.97 (22.5)
|
22.37 (22.5)
|
Cape Coral Bridge
|
27.46 (27.1)
|
30.21 (30.4)
|
Shell
Point
|
34.15 (34.2)
|
35.34 (35.6)
|
Salinity
at the Ft. Myers surface sensor remains above the
1-day MFL maximum criterion of 20 ppt. The current surface salinity of 14.46 ppt at S-79 is 5.54 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.
Biscayne Bay
Salinity Report for January
2008. The mean monthly salinity nearshore Manatee
Bay increased 18 percent
from December (24.5 psu) to January (29.0 psu) (Figure 1), but was 32 percent below the maximum
salinity of 42.5 psu recorded during February
2005. Within the last twelve months,
mean monthly salinity has increased steadily from a low in October (18.0 psu), but is still below the high set last May (34.7 psu).

Figure 1
Water Conservation Areas
Dry season recession rates have returned to a typical pattern throughout
the Greater Everglades. Recession rates
are good throughout WCAs 1 and 2, ranging from
-0.05”/week to -0.16”/week. While
recession rates in most of WCA-3A are still poor,
this week’s values are much better than those from last week and are beginning
to decline. Water depths are still
rather high for good wading bird foraging in most of the conservation
areas. Foraging conditions are good to fair
locally only in WCA-2B, northern WCA-3A,
and all of WCA-3B. Water depths range from 0.15’ to 2.24’ at all
reporting gauges.
Stages in WCA-1 are about at regulation,
the WCA-2A marsh has declined slightly from last week
but is still far above regulation, and WCA-3 stages
are slightly under regulation.
Everglades National
Park
Everglades
National Park (ENP) stations have not transmitted
data since 2/28 (with latest data through 2/27), so data are not current.
Rainfall
was patchy again last week across ENP and Florida Bay.
The ENP basin spatially-averaged RAINDAR total for the week was .22”. Estimated weekly totals near or exceeding 1”
occurred in southeastern areas of the ENP and in Florida Bay.
The C-111 basin-wide RAINDAR total for this
period was 0.62”. The USGS gauge at W. Highway Creek. reported
just under 0.5” of rain for the week.
Rain in the region was heaviest on Wednesday, 2/27 (with little recorded
since then).
Data
are insufficient to estimate weekly water level trends across ENP wetlands, with EDEN
stage data extending only through Friday, 2/29.
The 5-day trends (using the EDEN
estimates) indicate decreased water levels in SRS (station P33) by just under 1”, with increased levels in the panhandle (station EVER6) by approx 0.5”.
No EDEN data are available for Taylor Slough
Bridge, and data for
Craighead Pond looked suspicious.
Salinity
concentrations remained generally stable or declined slightly in Florida Bay last week. Salinity dropped into the low-20s at Trout
Creek. At the mouth of Taylor River
salinity read near 20 psu for another week Salinity
concentrations in the Taylor
ponds remained in the single digits last week (USGS station at Pond 5).
The 30 day moving average concentration at Argyle Hendry (station TR, used to track Florida Bay MFL
criterion) is unavailable. Salinity
concentrations dropped below 20 psu in the
north-central Bay area of McCormick Creek.
As a whole these salinity concentrations are near seasonal norms.
Water Supply
Water
levels in the upper and lower Kissimmee
Basin and remain slightly
below 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 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.
There
is no change in the Water Supply Risk indicators this week. Six out of eleven 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.
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