MEMORANDUM
TO: Chip
Merriam, Deputy Executive Director, Water Resources
FROM: SFWMD Staff Environmental Advisory Team
DATE: April 8, 2008
SUBJECT: Weekly
Environmental Recommendation for Systems Operations
Recommendation
No Lake Okeechobee regulatory releases to the
south or estuaries are recommended.
Background
Showers south today, then drier.
A frontal boundary is becoming diffuse across the area and an upper
level energy impulse is tracking eastward through the Florida Straits. Expect some patches of light rain mixed with
embedded showers to move across the southern half of the District today. A drier pattern is forecast to set up
Wednesday with just some spotty shower activity through Saturday. A cold front is expected to bringing light
to moderate shower activity Saturday night and Sunday. The next ten days precipitation outlook is below
average with moderate confidence.
Kissimmee Watershed
Over the last seven days, the upper Kissimmee Basin
received 3.57 inches of rainfall to bring the 30 day total to 4.27 inches (140%
of average), and the lower basin received 3.39 inches to bring the 30 day total
to 4.39 inches (160% of average).
The discharge from Lake
Kissimmee (S-65) continues in the
range of 1500-2000 cfs to continue a gradual water
level recession and provide flow to the Kissimmee River. Releases are no longer being made from Lake Toho
(S-61) or East Lake Toho (S59). Releases
from Lake Gentry are being made at 970 cfs. No other
releases are being made 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.
Flow has been reestablished to the Kissimmee River for 258 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 2.3 mg/L to 7.6 mg/L with an
average of 3.8 mg/L.
Lake Okeechobee
According to the USACE
web site, Lake Okeechobee stage is 10.48’ NGVD, which is 0.19’ higher than a week ago and 0.38’
higher than a month ago. The current
stage is 0.39’ higher than it was a year ago and 3.75’ below its historical
average for this time of year. Total
inflows exceed 4500 cfs and include the Kissimmee River (~1800 cfs),
S71 and S72 (~1800 cfs), S84 (~150 cfs), S77 (~100 cfs), and the L8
at Canal Point (~730 cfs). No outflows are reported. Weekend rainfall totals at sites around the
lake ranged from 1.50” at the Okeechobee Field Station to 3.74” at the S77.
Monthly phytoplankton monitoring was performed on
March 26th. Six of nine sites
had sufficient water for sampling. Mean secchi depth was 0.18 m.
Chlorophyll and toxin data are not yet available, but there was no
visual evidence of bloom conditions at any of the sites.
St. Lucie Estuary
There were no releases through S-80 over the past
week. There was very little discharge at
S-49 on the C-24 canal and no discharge at S-97 on the C-23 canal. The current weekly average salinities (in
bold) at the four monitoring sites in the St. Lucie Estuary are given below in
parts per thousand (ppt). Current weekly averages may be compared with
the previous week’s data (in parenthesis).
|
Weekly Average Salinity (ppt)
|
|
Sampling Site
|
Surface
|
Bottom
|
Envelope
|
Palm City
Bridge (S. Fork)
|
11.55 ( 11.77)
|
12.64 (12.99)
|
|
HR1 (N. Fork)
|
12.09 (15.77)
|
13.45 (NR)
|
|
Roosevelt Bridge
|
16.22 (17.87)
|
16.98 (18.55)
|
8.0 – 25.0
|
A1A Bridge
|
25.35 (26.93)
|
27.56 (29.10)
|
20.0 – 31.0
|
In general, average salinity decreased during the
past week 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
16.22 ppt at the Roosevelt Bridge
is 11.78 ppt below the maximum weekly average of 28.0
ppt achieved in May 2001 during the 2000 – 2001 drought.
Caloosahatchee Estuary
Weekly average discharge of 197 cfs
occurred at S-79 last week. Discharge
from S-77 into Lake Okeechobee averaged 77.71 cfs. The
concentration of chlorides at the Olga Plant is 163 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)
|
14.45 (15.05)
|
14.50 (16.12)
|
Rt. 31 Bridge
|
15.06 (14.19)
|
16.15 (18.87)
|
I-75 Bridge
|
NA (14.71)
|
20.17 (19.52)
|
Ft. Myers
Yacht Basin
|
23.19 (21.67)
|
23.32 (23.94)
|
Cape
Coral Bridge
|
28.06 (27.65)
|
28.77 (29.00)
|
Shell Point
|
34.33 (33.97)
|
35.22 (34.93)
|
Compared with last week, average surface salinities
decreased only at S79. Average bottom
salinities decreased for most sites in the estuary. Salinity at the Ft. Myers
surface sensor remains above the 1-day MFL criterion
of 20 ppt. The
current surface salinity of 14.45 ppt at S-79 is 5.55
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 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 no Karenia
brevis, the Florida red tide organism, was detected this
week in water samples collected alongshore between Pinellas and Monroe
counties.
Water Conservation Areas
While rainfall is generally welcome in
a drought, it has continued to interfere with the traditional breeding patterns
of wading birds in the Everglades. Water levels rose throughout the Everglades. Stages
increased the most in northern WCA-3A, where the
greatest rain fell, and least in WCA-3B. The
high rainfall has produced large reversals
throughout the Everglades, ranging from 0.05”
up to 0.68”, producing poor foraging conditions for wading birds. (Optimal recession rates are declines of
0.04-0.16’ per week.)
Depths similarly were poor for wading
birds throughout the region, ranging from 0.89’ to 2.56’ in the Conservation
Areas. Wading birds in general need
water depths from 0.1’ to 0.79’ to find appropriate prey species. The current water depths do not support
foraging, which is increasing concern for wading bird breeding success this
year. However, as reported last week, it
is still relatively early in the nesting season for ibis and it is hoped that
these poor hydrologic conditions will have a minimum impact on this species.
Marsh stages in WCA-1
have risen again and are above Regulation, WCA-2A
marsh remains at levels above regulation and canals have likewise risen, and WCA-3A stages have reached the top of zone E1 of the
regulation schedule, which is designed for protection of the Cape
Sable Seaside Sparrow.
Everglades National
Park
Everglades National Park (ENP)
and Florida Bay saw substantial rainfall last week,
particularly Sunday with 7 day accumulations ranging between 0.7” – 2.6”. The basin-wide spatially-averaged Raindar totals for the week were 1.8” for the ENP basin and 2.0” in the C-111 basin; precipitation is not
accounted for yet in description of stage/salinity trends below.
ENP wetland water levels showed
mixed trends last week, due in part to the timing and distribution of Sunday’s
rain event. Water levels were down in
both northern and southern areas of Taylor Slough; at Taylor Slough
Bridge daily mean water
levels dropped by 4.3” over the week (not unusual for this station, and hourly
measurements showed it rising quickly after Sunday’s rain event). To the south in Craighead Pond, stage decreased
by 1.2” for the 7 day period. In the
Shark River Slough system, though, water levels increased by just over 2.5” at
station P33 over the week, in response to heavy rainfall in this area over the
past 2 weeks. Data from the panhandle
(station EVER6) have been unreliable of late.
The salinity pattern in Florida Bay
and surrounding embayments was also variable last
week. Salinity remained just above 30 psu at Trout Creek. A flow reversal in Taylor River
increased salinity into the upper-20s at the mouth and up towards 25 psu in the ponds (at both Pond 5 (USGS
station) and Argyle Hendry (ENP station TR)). As of Sunday,
the 30 day moving average concentration at Taylor River,
used for tracking the Florida Bay MFL criterion, was
at 13.7 psu, up from 9.5 psu
last week, and while not unseasonably high, the highest concentration we have
seen yet this dry season. The station at
the Little Madeira Bay mouth remains offline.
Strong flow reversals pushed Bay water northward
into the north central Bay areas of McCormick Creek and Terrapin Bay,
increasing salinity concentrations into the mid-30s. Data from the central Bay station at Whipray
Basin continue to be
patchy, so rainfall data haven’t been updated.
In contrast to trends elsewhere in the Bay, and probably the result of
local rainfall, salinity in Whipray declined a bit
last week to 37 psu over the weekend.
As a whole the regional salinity concentrations are
near seasonal norms except out west in areas downstream of Shark River Slough
(upstream reaches of Shark River) in Tarpon
Bay. There the daily mean measurement of 19 psu on Sunday is still well above normal for this station,
closer to concentrations experienced at the height of the dry season in May,
not surprising with the low water levels and flows through SRS this water year.
Wildlife:
Spoonbill nesting: - Audubon reported Spoonbill
nesting in Eastern
Florida Bay
at 3 nests, all of which were monitored.
In late March, 1 nest failed and 1 chick survived to 21 days. In Western
Florida Bay,
significant colony activity was detected in late January, likely a second
nesting attempt by birds at Palm Key.
While they haven’t visited the site yet, they saw more than 40 adults
and at least 5 large chicks at the colony.
Audubon staff plan to visit the site this week. With the rainfall, stages should rise
substantially this week.
Other wading birds: - The colony flight on Tuesday,
April 1, was notable for the absence of wading birds in the northern Everglades.
Scientists counted a total of only 605 nests (585 Great Egret and 20
White Ibis nests), in sharp contrast to the April counts of 2006 and 2007 when
they observed approximately 37,000 and 18,000 nests, respectively. April tends to be the month of peak nesting
activity, and we could yet see a late surge in ibis nesting activity if foraging
conditions improve soon. However, it is
now highly unlikely that storks will initiate breeding.
Most areas of the WCAs
were largely devoid of birds. Northwest WCA-3A
supported moderate numbers of birds, including storks and spoonbills but
scientists noted no large foraging flocks. A few large flocks of ibis were
observed in western WCA-1 but few birds were seen
elsewhere in the Refuge (see nest numbers table for more details).
Water Supply
Water levels in the upper and lower Kissimmee Basin are now near their historical
average conditions for this time of year – they rose somewhat this past week as
a result of local rains. 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 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 or
slightly above their average historic conditions.
There was continued modest improvement in the Water
Supply Risk indicators this week. 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 Palmer Index for Lake
Okeechobee tributary conditions and Climate Prediction Center
Precipitation Outlook are now in the “medium” risk category.
The Lake Okeechobee Seasonal and Multi-seasonal Net
Inflow Forecasts are now at “low” 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