M E M O R A N D U M
TO: Chip
Merriam, Deputy Executive Director, Water Resources
FROM: SFWMD
Staff Environmental Advisory Team
DATE: May 20, 2008
SUBJECT: Weekly
Environmental Recommendation for Systems Operations
Recommendation
No
Lake Okeechobee regulatory releases to
the south or estuaries are recommended.
Background
Daily
shower activity is forecasted this week.
A weakening frontal boundary across central Florida is tapping decent moisture over the
area to generate scattered showers today focused north and east each day. The old front will become more diffuse on
Wednesday so afternoon shower and thunderstorm coverage will decrease a
bit. Activity should remain focused
north and east Saturday. Building high
pressure should bring a return of drier conditions by Monday. The next ten days precipitation outlook is
below average with low confidence.
Kissimmee Watershed
Over the last
seven days, the upper Kissimmee Basin received 0.02 inches of rainfall to bring
the 30 day total to 0.15 inches (5% of average), and the lower basin received
0.01 inches to bring the 30 day total to 0.08 inches (3% of average). Releases from East Lake Tohopekaliga
(S-59) continued at 180 cfs. Releases from Lake Tohopekaliga
(S-61) ceased today. Releases from the
Alligator Chain (S-60) ceased. Releases
from Lake Gentry decreased to 60 cfs. Releases from Lake Kissimmee
(S-65) continued at 400 cfs.
In the upper basin, snail
kites continue to nest on East Lake Toho, Lake
Toho, and Lake Kissimmee.
Nests on Lake
Toho continue to represent a large
fraction of the total number of snail kite nests in Florida.
Flow has been
reestablished to the Kissimmee River for 300
days (S-65 re-opened on 07/18/07). With
the decreased inflow from the upper basin, water levels continue to decline
across the Kissimmee River Restoration Project. The water level at Weir 3, near the upstream
end of the Phase I area, has fallen about 0.75 ft in the last week to 37.03
feet. The headwater stage at S-65C has
decreased 0.49 feet to 33.97 feet, so that the water surface elevation
decreases by 3.06 feet from the upstream end to the downstream end of the
restoration project.
Dissolved oxygen data are
currently unavailable due to technical difficulties.
Lake Okeechobee
According to the USACE web site, Lake Okeechobee
stage is 9.78’ NGVD, which is 0.20’ lower than a week
ago and 0.66’ lower than a month ago.
The current stage is 0.48’ higher than it was a year ago and 3.53’ below
its historical average for this time of year.
Reported inflows include ~250 cfs from the Kissimmee River.
Outflows include 417 cfs through the S352 and
112 cfs through the S77.
A muck burial demonstration
project was completed last week in the lake’s littoral zone adjacent to the Indian Prairie
Canal. Four different tilling and disking methods
are being tested for their ability to sequester soil phosphorus and improve
vegetation conditions. A total of 40
acres have been treated. Pre- and post-treatment
sampling was conducted to measure effects on soil phosphorus retention and the
plant seed bank.
Wildfires continue to burn in
the littoral zone in the southwest corner of the lake. Approximately 26,000 acres have now
burned. The Grassy Island
fire is completely contained. The Myakka
Cut fire is 50% contained but continues to spread actively to the
east-northeast. Three smaller wildfires
(<100 acres total) have been reported along the western shore and all but
one of these has been contained.
St. Lucie Estuary
There were no releases
through S-80 from C-44, S-49 from C-24, and S-48 from C-23 over the past
week. 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)
|
19.24 (16.60)
|
20.81 (17.99)
|
|
HR1 (N. Fork)
|
20.62 (18.26)
|
22.85 (20.64)
|
|
Roosevelt Bridge
|
22.95 (17.82)
|
24.22 (19.88)
|
8.0 – 25.0
|
A1A Bridge
|
30.30 (26.98)
|
31.83 (30.19)
|
20.0 – 31.0
|
Average salinity increased
about 3 ppt in North Fork and South Fork, 5 ppt at Roosevelt
Bridge, and 2-4 ppt at A1A Bridge. Both the surface and bottom salinity are in
the preferred range at the Roosevelt
Bridge. The bottom salinity at A1A
Bridge exceeded the preferred range.
Salinity conditions in the estuary are considered fair, based on the
salinity preference of the oyster, Crassostrea
virginica, at Roosevelt Bridge. The current surface salinity of 23 ppt at the Roosevelt
Bridge is 5 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.
Caloosahatchee Estuary
No discharge occurred through
S-79 during the past week. An average
weekly discharge of 184 cfs occurred at S-77and 102 cfs at S-78. The concentration of chlorides at the Olga
Plant was 237 ppm yesterday, down from 276 ppm in the beginning of this reporting period. 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)
|
16.74 ( 14.97)
|
17.25 (15.73)
|
Rt. 31 Bridge
|
17.67 (17.52)
|
18.67 (17.79)
|
I-75 Bridge
|
18.64 ( 18.60 )
|
20.08 (19.23)
|
Ft. Myers Yacht Basin
|
24.41 (23.60)
|
24.56 (23.70)
|
Cape Coral Bridge
|
31.47 (30.73)
|
32.13 (31.10)
|
Shell Point
|
35.67 (35.38)
|
36.38 (36.08)
|
Average salinities increased
about 1 ppt throughout the estuary. Salinity at the Ft. Myers
surface sensor was above the 1-day MFL criterion of
20 ppt. The
current surface salinity of 16.7 ppt at S-79 is 3.3 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 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 seagrasses.
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
As in past weeks, recession
rates were high in almost all the WCAs due to the
lack of rain and high evapotranspiration, and water depths
are now declining to depths that are fair to good for wading bird foraging over
much of the conservation areas. In some
regions the recessions were actually a little too high but this is not a concern given water depths are in general at the high end
of wader foraging ranges, especially in WCA-3A and
3B. Stages throughout the WCA’s continue to decline and are above Regulation in WCA-2A, at regulation in WCA-1
and below regulation inWCA-3A.
Everglades National Park
Little rainfall & high evapotranspiration (ET) caused water levels to decline
across Everglades National Park (ENP) wetlands last
week. Water levels dropped by 4.4” at Taylor Slough
Bridge and by nearly 3”
in the southern part of Taylor Slough (at Craighead Pond). At the panhandle station @ EVER6,
water levels were down substantially, by just over 2.75”. Shark
River Slough
(station P33, where no rainfall was measured last week) declined only 0.3”.
Salinity rose across much of Florida Bay last week due to strong southerly
winds and high rates of evaporation. Concentrations
herein described should be near their seasonal peaks, unless the rains don’t
kick in soon. Salinity rose slightly in
the northeast Bay, into the upper 30s at Trout Creek and Long Sound/Highway Creek,
and toward the middle-30s at the mouth of L. Madeira Bay. In the Taylor
ponds, daily mean salinity remained over 30 psu at
Pond 5 (USGS station) and Argyle Hendry (ENP station TR) for the entire
week. As of Sunday, 5/18, the 30 day
moving average concentration at TR (used for tracking
the FL Bay MFL criterion) was at 28.2 psu (up from 24.6 psu last week);
with concentrations already over 30 psu for 11 days
straight, and sustained high temps & ET, it is possible that we will exceed
the 30 psu salinity criterion this dry season at TR. Salinity rose near 40 psu
in the north central Bay areas of McCormick Creek and Terrapin Bay.
At the central Bay station in Whipray
Basin salinity moved into
the lower-40s. Salinity in the upstream
reaches of Shark River
(Tarpon Bay platform) measured slightly above
the seasonal norm (mid-teens), holding near 20 psu.
Water Supply
Last week was dry again, so
most water levels decreased across the District. Water levels in the upper and lower Kissimmee Basin are now near or slightly below their
historical average conditions for this time of year. Water levels in the Lower
West Coast are now near their historical averages, though some
water levels (e.g., Sandstone Aquifer) are below those conditions depending on
the degree of confinement of the aquifers.
Water levels in the Lower East Coast
are near or slightly below their historical averages. Water levels in the Upper
East Coast are now near their historic averages although they
declined this past week. Surface and
groundwater levels in Water Conservation Areas 1, 2 and 3 are now near or
slightly above their historic averages – although they have been declining
steadily over the past week. Water
levels in the southernmost portion of Miami-Dade County
are now below their average historic conditions.
There was no change in the
water supply risk indicators since last week.
Six out of the eleven water supply risk indicator parameters are now in
the “low” risk category, including the CPC Precipitation Outlook, the Lake
Okeechobee Seasonal and Multi-seasonal Net Inflow Forecast, and Water
Conservation Areas 1, 2A and 3A.
Four out the eleven water
supply risk indicators are now in the “medium” risk category, including the
Palmer Index for Tributary Conditions (dry) 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)
LORS2008 (Lake Okeechobee
Regulation Schedule)
The current Lake
Okeechobee stage remains in the Water Shortage Management zone and
is unlikely to move back into the Operational Band in the next several months
during the persistent La Niña climactic conditions.
CC: George Horne