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: September 16, 2008
SUBJECT: Weekly
Environmental Conditions for Systems Operations
Summary
Inflows from the tributary
basins have continued to taper off but remain in the very wet tributary
hydrologic conditions. Stages in Lake
Okeechobee (
Background
Daily scattered shower activity.
An upper level low in the northeastern
Over the last
seven days, the upper
Water levels in
all of the upper basin lakes are very close to their regulation schedules. Releases are being made from
Discharge from
Water depths on
the floodplain within the restoration project have decreased by about 1.5 feet over
the last week. However, some areas are
still as deep as 4.8 feet.
From 9/09/08 to
9/16/08 dissolved oxygen concentrations in the
According to the USACE web
site,
The monthly
submerged-aquatic-vegetation (SAV) survey was completed yesterday and 16 of the
32 sites visited had plants. Last month
(pre Tropical Storm Fay) 24 of the 35 sites visited had plants. Water clarity has decreased with an average secchi depth:total
depth ratio of 0.34 compared to 0.96 last month. The decrease in light conditions along the
northwestern shoreline and in
Monthly phytoplankton
monitoring was performed 9/ 15/08. For
the first time in over a year all nine sites had sufficient water for sampling.
Toxin and chlorophyll data are not yet
available but minor blooms were observed at most of the northern stations and a
more significant bloom was seen in Harney Pond. An increase in bloom formation may occur as
terrestrial vegetation in the newly inundated littoral zone die and release
nutrients into the water column.
Large areas of spikerush and cattail persist at water depths of 1.6 to 1.7
m along the western shoreline. The lakeward edge of this vegetation is showing clear signs of
stress while plants closer to shore still appear healthy. Bulrush, an important component of the
shoreline vegetation community in the past, is conspicuously absent.
St. Lucie Estuary
During the last week, an
average discharge of 1107 cfs occurred at S-80 from
C-44 (including 789 cfs at S308 from the
|
Weekly Average Salinity
(ppt) |
|
|
Sampling Site |
Surface |
Bottom |
Envelope |
|
0.26 (0.22)
|
0.26
(0.22) |
|
HR1 (N. Fork) |
0.36 (0.29) |
0.49 (0.47) |
|
|
0.93 (0.92) |
1.21 (1.66) |
8.0 – 25.0 |
A1A Bridge |
6.55
(6.48) |
18.29 (16.66) |
20.0 – 31.0 |
Compared with salinities of
the previous week, average salinity in the estuary increased only slightly in
the estuary (<1 ppt for most locations) except for
the bottom salinity at Roosevelt Bridge A1A which decreased by 0.5 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 3016 cfs occurred at S-79 including 1166 cfs at S-77 from the
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 |
|
0.22 (0.21) |
0.22
(0.22) |
Rt. 31 Bridge |
0.22
(0.21) |
NR (NR) |
I-75 Bridge |
0.25 (0.24) |
0.23
(0.22) |
|
0.41 (0.23) |
0.43 (0.23) |
|
2.63 (1.15) |
7.00 (1.60) |
Shell Point |
17.92 (11.16)
|
22.24 (16.62) |
In the estuary, freshwater
conditions extend from S-79 downstream close to
Salinity at
No Karenia brevis, the
Water Conservation
Areas
Water depths in
the Greater Everglades (GE) range from a high of 4.13 feet in southern region
of WCA-2B to a low of 1.43 feet in NE Shark River Slough. The GE has now reached a state where large
areas of the GE are currently over 2.5 feet.
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 and some areas of WCA-3A are now 49 days
above the tree island threshold and WCA-2A is now 28 days above this threshold.
WCA-1 stages
continue to drop and are still below the regulation schedule. WCA-2A stages are beginning
to drop, but remain well above regulation and has been above regulation
since Oct. 1, 2007 (i.e., the last 11 months). WCA-3A stage continues to rise and
has been above regulation since mid-July.
Last week brought significant
rainfall to portions of Everglades National Park (ENP) and
by 1.6” for the week at
Salinity trends across
Water Supply
Water levels declined
slightly across most of the District after enjoying a substantial rise
(increase) as a result of Tropical Storms Fay, Hanna and Hurricane Ike. Water levels in the upper and lower
All 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 and LEC Service Areas 1, 2 and 3 (as a result
of the removal of water restrictions) are now in the “low” risk category.
LORS2008 (
Stages in
CC: George Horne