MEMORANDUM
TO: Chip Merriam, Deputy Executive
Director, Water Resources
FROM: SFWMD
Staff Environmental Advisory Team
DATE: April 22, 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 surface low off the coast of South Carolina is expected to dig southward to off the
coast of Jacksonville
Wednesday. Some moisture will wrap around
its backside Wednesday and generate some spotty showers northeast Wednesday
night. As the low exits to the east, a
reinforcing trough will pinwheel around the low and bring some scattered
showers mainly north and east Thursday and then south and west Friday. The next ten days precipitation outlook is below
average with moderate confidence.
Kissimmee Watershed
Over the last seven days, the upper Kissimmee Basin received 0.03
inches of rainfall to bring the 30 day total to 3.75 inches (142% of average),
and the lower basin received 0.01 inches to bring the 30 day total to 4.10
inches (170% of average). In the upper
basin, water levels are falling in most of the smaller lakes without having to
make releases for the spring recession.
Releases are being made from East Lake Tohopekaliga
(S-59) of 100 cfs, from Lake
Tohopekaliga
(S-61) of 400 cfs, and from Lake Kissimmee
(S-65) of 1100 cfs.
No other releases are being made in the upper basin.
Hydrilla treatment continued in Lake
Cypress last week. For the first week of treatment, inflow from Lake Tohopekaliga
and Lake Gentry was restricted. Hydrilla treatment
will continue.
The
vegetation removal project is continuing in Lake Gentry. The Florida Fish and Wildlife Conservation
Commission anticipates completing the project by the
end of this week. 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) was
decreased from 1500 cfs to 1100 cfs
to slow the water level recession to more closely track the environmental
recession line for snail kites and wading birds. Flow has been reestablished to the Kissimmee River for 272 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 2.1 mg/L to 8.4 mg/L with an average of 3.9
mg/L, which is a slight increase over last week’s report.
Aerial
surveys completed on April 10th found low numbers of wading birds
within the restored section (ca. 13 birds/km2),
while three large flocks of Glossy and White (mostly white) ibis were feeding
in Pool D in isolated depressional wetlands that had
been re-flooded after the prior week’s rain event, making the density in that
pool ca. 61 birds/km2. Ground
surveys found over 1,500 migratory shorebirds (mostly Dowitchers,
and Lesser and Greater yellowlegs) foraging over
backfill and scraped areas in Phase IVa last week.
Lake Okeechobee
According
to the USACE web site, Lake
Okeechobee stage is 10.41’ NGVD, which
is 0.07’ lower than a week ago and 0.25’ higher than a month ago. The current stage is 0.50’ higher than it was
a year ago and 3.50’ below its historical average for this time of year. Total reported inflows of ~1500 cfs and includes the Kissimmee River
(~1400 cfs) and the L8 at Canal Point (~100 cfs). Outflows of
359 cfs are reported through the S77.
Field
crews reported algal bloom conditions at several locations in the lake last
week. A surface bloom (possibly the
toxin-producing Microcystis) was observed near
the Pahokee Marina and evidence of bloom formation also was found at stations LZ40 (center of the lake), L005 (near the western shore),
and L001 (near the northern shore).
Monthly phytoplankton monitoring is being conducted this week and
samples will be collected for taxonomic analysis and toxin measurements.
St. Lucie Estuary
There
were no releases through S-80 over the past week. During this same period, discharge was
minimal at S-49 from C-24 and at S-49 from the C-24, respectively averaging
1.64 cfs and 0.07 cfs. 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)
|
11.09 (10.13)
|
12.44 (10.41)
|
|
HR1 (N. Fork)
|
14.04 ( 9.19)
|
16.87 (13.40)
|
|
Roosevelt Bridge
|
15.93
(13.08)
|
18.02 (15.03)
|
8.0 – 25.0
|
A1A Bridge
|
24.66 (23.60)
|
27.79 (27.52)
|
20.0 – 31.0
|
Average
salinity increased 1 to 2 ppt in the South Fork, 3 to
5 ppt in the North Fork, 3 ppt
at Roosevelt Bridge, and 1 ppt
on the surface at A1A Bridge during the past week. Both the surface and bottom salinity are in
the preferred range at the Roosevelt
Bridge, and at the A1A Bridge. Salinity
conditions in the estuary are considered good, based on the salinity preference
of the oyster, Crassostrea virginica, at Roosevelt Bridge. The current surface salinity of 16.0 ppt at the Roosevelt
Bridge is 12 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.
Caloosahatchee Estuary
The
direction of flow though S-77 at the beginning of the week was 166 cfs into Lake Okeechobee. However, the net flow for the week from S-77
was 100 cfs into the eastern C-43 basin. The S-78 gates were closed and there was no
discharge through S-79 during the past week.
The concentration of chlorides at the Olga Plant yesterday was 186 mg/l,
up from 155 mg/l last week. 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)
|
11.06 (9.03)
|
11.73 (9.60)
|
Rt.
31 Bridge
|
10.89 (9.39)
|
NA (9.58)
|
I-75
Bridge
|
NA ( NA)
|
15.01 (16.04)
|
Ft. Myers
Yacht Basin
|
19.40 (19.95)
|
20.41 (21.16)
|
Cape Coral Bridge
|
26.95 (26.87)
|
27.71 (27.74)
|
Shell
Point
|
33.40 (33.44)
|
34.15 (34.25)
|
Average
salinities increased 1 to 2 ppt in the upper estuary
and remained the same in the lower estuary.
Salinity at the Ft.
Myers surface sensor was
again just below the 1-day MFL criterion of 20 ppt. The current
surface salinity of 11 ppt at S-79 is 9 ppt below the maximum weekly average of 20.0 ppt achieved in May 2001 during the 2000 – 2001 drought. Salinity at
Shell Point and the Cape Coral
Bridge is near or above
the optimal range for the oyster, Crassostrea
virginica. Conditions in the upper estuary east of Ft. Myers
are poor due to high salinity. Conditions
in the lower estuary downstream of Cape
Coral are fair considering the combine salinity
preference of oysters and seagrass.
Water Conservation Areas
Low rainfall, high evapotranspiration
and water management releases resulted in generally fair or good recession
rates in WCA-1, WCA 2-A and
WCA 3-A, but depths in most areas remain well above
the 1 foot maximum threshold for wading bird foraging. Stages in WCA-1 have
declined and are now very close to Regulation Schedule, WCA-2A
marsh remains well above regulation, and WCA-3A
stages have declined and closely tracked regulation schedule.
Everglades National
Park
In
contrast to recent weeks, Everglades National Park (ENP)
and Florida Bay saw very little rainfall last
week. In ENP,
water level declined by 4.3” over the 7 day period at Taylor Slough
Bridge (not an unusual recession
rate at this station). The southern part
of Taylor Slough (at Craighead Pond) & northern areas of Shark River Slough
(station P33) both saw weekly recession of 1.3”. Reliable water level readings
for the panhandle station at EVER6 were unavailable
this, but at EPSW (west of EVER6)
stage was down by 1.2” for the week.
Salinity
in Florida Bay increased last week. Salinity rose above 30 psu
again at Trout Creek and remained in the upper-20s at the mouth of L. Madeira
Bay. In the Taylor ponds, salinity rose into the lower mid-20s
by the weekend at Pond 5 (USGS station) and Argyle
Hendry (ENP station TR). As of Sunday, 4/20, the 30 day moving average
concentration at TR (used for tracking the FL Bay MFL criterion) was at 17.5 psu
(up from 16.7 psu last week, and while not
unseasonably high, the highest concentration we have seen yet this dry
season). Salinity also increased in the
north central Bay areas of McCormick
Ck. & Terrapin Bay, where concentrations once again rose
into the mid-30s by the week’s end. At
the central Bay station in Whipray Basin
salinity increased slowly through the week, into the upper-30s. These salinity concentrations across FL 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 again this week
(probably in response to recent rain events), down into single digit
concentrations (~ 9 psu) as of Sunday, 4/20, near its
seasonal norm. It has been greater then
3 months since salinity was this low in this part of the system.
Water Supply
Last
week was relatively dry, most water levels decreased slightly across the South
Florida Water Management District. 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 average to slightly higher 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 above
their average historic conditions.
Five
out the eleven water supply risk indicator parameters are now in the “low” risk
category, including the Lake Okeechobee Seasonal and Multi-seasonal Net Inflow
Forecast, and Water Conservation Areas 1, 2A.
Five
out the eleven water supply risk indicators are now in the “medium” risk
category, including the Palmer Index for Tributary Conditions (dry) and the CPC
Precipitation Outlook (normal to below normal) and the LEC
Service Areas 1, 2 and 3.
The
only risk measure that is in the “high” risk category is the projected Lake
Okeechobee Stage (water restriction zone).
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