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: August 26, 2008
SUBJECT: Weekly
Environmental Recommendation for Systems Operations
Recommendation
No
Lake Okeechobee regulatory releases to
the south or estuaries are recommended.
Background
Showers
and storms focused interior south on Tuesday, interior west Wednesday and west
on Thursday. Steering flow remains from
the south this morning. This is not a
dry direction. Look for seabreeze enhanced showers/storms to focus over interior
areas south and around
Over the last seven days, the
Water levels in all of the
upper basin lakes are above their regulation schedules except for
According to the Florida Fish
and Wildlife Cooperative Research Unit at The University of Florida, all known
snail kite nesting in the
Due to the heavy rainfall
associated with Tropical Storm Fay, discharge from
Water depths on the
floodplain within the restoration project currently range from 2.5 – 6.8 feet. The floodplain in the restored reach is
completely inundated at this time.
From 08/19/08 to 08/26/08
dissolved oxygen (DO) concentrations in the
According to the USACE web
site,
Field crews began conducting post-Fay assessments of
water-quality, phytoplankton, and submerged aquatic vegetation (SAV) last
Friday (8/22/08). Initial reports show
increased turbidity across most of the nearshore zone
and an absence of algal blooms. Underwater light conditions for SAV growth
ranged from poor (secchi depth:total depth ratio of 0.1) to marginal (sd:td of 0.3-0.4), with the southern shoreline having the
least turbidity and the northern shoreline having the greatest. High flows in Fisheating
Creek appear to be maintaining low turbidity across
Post-storm sampling at SAV sites surveyed just 2-3 weeks ago
indicates that the SAV community remains largely intact despite maximum
sustained winds near 60 mph along the western shoreline during the storm. However, continued development of existing SAV
beds will be slowed if deep, turbid water conditions persist. Due to the rapid increase in water levels, many of these beds are
now at water depths of 1.0-1.5 m or greater.
However, increased lake stage has also resulted in the re-hydration of
shoreline areas that historically have contained extensive SAV beds. An aerial survey conducted on Monday indicated
that water clarity in these newly flooded areas is suitable for SAV germination
and growth.
Emergent wetland vegetation
along the shoreline also remains intact. Water depths have increased to > 1 m along
the outer wall of cattail and spikerush that developed
during the drought. Both of these
species are tolerant of deep-water conditions in wetlands such as the
St. Lucie Estuary
During the last week, an
average discharge of 915 cfs occurred at S-80 from C-44. Monday’s discharge was 1,451 cfs. An average discharge of about 3,000 cfs
occurred last week through S-49 from C-24. 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) and the
preferred range (envelope) at the two downstream sensors.
|
Weekly Average Salinity
(ppt) |
|
|
Sampling Site |
Surface |
Bottom |
Envelope |
|
1.43 (8.07) |
1.44
(9.56) |
|
HR1 (N. Fork) |
0.92 (7.71) |
1.20 (12.81) |
|
|
1.89 (11.13) |
1.96 (13.80) |
8.0 – 25.0 |
A1A Bridge |
3.82
(19.69) |
4.48
(24.63) |
20.0 – 31.0 |
Compared with salinities of
the previous week, average salinity in the estuary decreased about 8.12 to
20.15 ppt. All four monitoring stations
are reporting salinities below the preferred range. Salinity conditions in the estuary are
considered to be poor based on the salinity preference of the oyster, Crassostrea virginica, and
location in the estuary.
Caloosahatchee Estuary
An average weekly discharge
of 14,457 cfs occurred at S-79. Yesterday’s
discharge was 13,556 cfs. The
concentration of chlorides at the Olga Plant was 22 ppm
yesterday, down from 50 ppm at the beginning of this
reporting period.
Based on the USGS flow meter
located just below S-77 there was an average weekly discharge of 433 cfs. Prior to Tropical Storm Fay, S-78 remained
closed with no discharge since June 30th. S-78 opened on Aug. 18th with an
average discharge during the last week of about 5,920 cfs. Monday’s discharge was 4,987 cfs.
The current weekly average
salinities (in bold) at the six monitoring sites in the Caloosahatchee Estuary
are given below in parts per thousand (ppt), along with the previous week’s (in
parenthesis).
|
Weekly Average Salinity
(ppt) |
|
Sampling Site |
Surface |
Bottom |
|
0.16 (0.25) |
0.15
(0.25) |
Rt. 31 Bridge |
0.16
(0.26) |
NR (NR) |
I-75 Bridge |
0.19
(0.33) |
0.18
(0.30) |
|
0.28 (0.87) |
0.28 (1.08) |
|
NR (NR) |
NR (NR) |
Shell Point |
5.29 (22.17) |
7.35 (23.57) |
In the estuary, freshwater
conditions extend from S-79 downstream to Shell Point. Salinity conditions in the upper estuary east
of
Salinity at
No Karenia brevis, the
Water Conservation
Areas
June through
September is usually the time of year when the Greater Everglades (GE) is
expected to continuously rise at the rate of approximately 0.1 to 0.2 foot per
week. However, with the arrival of Tropical
Storm Fay it is no longer necessary or appropriate to track this re-hydration
rate. The GE has now reached a state
where most of the sentinel gages are at least 2 feet deep, and large areas of
the GE are currently over 2.5 feet deep. This 2.5 foot depth is a generalized threshold
for tree island inundation where continuous inundation of more than 120 days is
a potential health hazard for islands. Thus,
Inundation Days are now being tracked.
All the WCA
stages are above regulation. WCA-2A has
been above regulation since October 1, 2007 (i.e., the last 11 months).
Tropical Storm Fay delivered
some significant rainfall to the southern Everglades and
Salinity trends across
Water Supply
Water levels across the
District generally benefited as a result of Tropical Storm Fay. Water levels in the upper and lower
Eight out of the eleven water
supply risk indicator parameters are now in the “low” risk category, including
the CPC Precipitation Outlook, Palmer Index for Tributary Conditions, the Lake
Okeechobee Seasonal and Multi-seasonal Net Inflow Forecast, and Water Conservation
Areas 1, 2A and 3A. The projected Lake
Okeechobee Stage is now in the “low” risk category.
Three
out the eleven water supply risk indicators are now in the “medium” risk
category, including LEC Service Areas 1, 2 and 3.
LORS2008 (
Rainfall from Tropical Storm
Fay significantly increased
CC: George Horne