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 23, 2008
SUBJECT: Weekly
Environmental Conditions for Systems Operations
Summary
Inflows from the tributary
basins have continued to taper off and are now in the wet tributary hydrologic
conditions. Stages in Lake Okeechobee (
Background
Rains Tuesday, then significantly drier tomorrow into the
weekend. A developing trough over the southeast
Over the last
seven days, the upper
Releases are
being made from
Discharge from
Water depths on
the floodplain within the restoration project have decreased by about 1.0 foot
over the last week. In general,
floodplain depths in the restored area range from 0.5 feet to 3.0 feet.
From 9/16/08 to
9/23/08 dissolved oxygen (DO) concentrations in the Kissimmee River ranged from
0.3 mg/L to 2.8 mg/L and averaged 1.4 mg/L, a slight increase from last week. DO concentrations are still below levels of
concern at certain times but are showing signs of improvement.
According to the USACE web
site,
The annual mapping of the
entire submerged aquatic vegetation (SAV) community was completed in early
August (prior to Tropical Storm Fay). The
abundance of SAV at approximately 377 shoreline sites has been documented and
preliminary results indicate that SAV covers a total of 35,834 acres.
This is an increase of 7654 acres of SAV coverage from last year’s annual
mapping (28,180 total acres). Chara remains the dominant plant species, covering
28,268 acres along the southern and western shorelines. Vallisneria
increased in areal coverage from 494 acres last year
to 9405 acres this year and is most abundant in
A bloom of cyanobacteria, tentatively identified as the
toxin-producing Microcystis, spread rapidly
across the northern part of the lake last week, and bloom conditions also were
observed near Pahokee on Thursday. Yesterday, field crews reported a moderate
bloom in
Periodic sightings of the
non-native Purple Swamphen have occurred on the lake
this year. Approximately one dozen birds
were spotted yesterday in Bay Bottom at the south end of the lake. Florida Fish and Wildlife Conservation
Commission (FFWCC) is the lead agency responsible for their eradication.
St. Lucie Estuary
During the last week, an
average discharge of 1653 cfs occurred at S-80 from
C-44 and 2195 cfs at S308. Flow data of C-23 and C-24 were currently
inaccessible due to technical issues, but the discharge should be insignificant
considering that very limited rainfall occurred 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 |
|
0.33 (0.26) |
0.38 (0.26) |
|
HR1 (N. Fork) |
2.23 (0.36) |
5.45 (0.49) |
|
|
4.32 (0.93) |
6.36 (1.21) |
8.0 – 25.0 |
A1A Bridge |
14.77 (6.55) |
23.42 (18.29) |
20.0 – 31.0 |
Average salinity increased
about 0.1 ppt in the South Fork to about 8.2 ppt at the A1A Bridge compared with that of the previous
week. All four monitoring stations are
reporting salinities below the preferred range, except for the bottom salinity
at A1A Bridge. Salinity conditions in
the estuary are still 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 3745 cfs occurred at S-79, 2328 cfs at S-78, and 2634 cfs at
S-77. The concentration of chlorides at
the Olga Plant was 43 ppm yesterday, down from 45 ppm at the beginning of this reporting period. 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 |
|
0.24 (0.22) |
0.24 (0.22) |
Rt. 31 Bridge |
0.24 (0.22) |
0.24 (NR) |
I-75 Bridge |
0.26 (0.25) |
0.27 (0.23) |
|
0.34 (0.41) |
0.36 (0.43) |
|
3.45 (2.63) |
5.17 (7.00) |
Shell Point |
16.66 (17.92) |
19.42 (22.24) |
In the estuary, freshwater
conditions extend from S-79 to downstream of
Salinity at
Fish and Wildlife Research Institute (FWRI) reports that background concentrations of Karenia brevis, the
Water Conservation
Areas
Water depths in
the Greater Everglades (GE) range from a high of 3.99 feet in the southern
region of WCA-2B to a low of 1.36 ft in central WCA-1. The GE has now reached a state where large
areas of the GE are currently over 2.5 ft. 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. The southern region WCA-3A is now 56 days
above the tree island threshold, central WCA-2A is now 42 days above this
threshold, and the ponded region of WCA-2B is now 70
days above this threshold.
WCA-1 stages
continue to drop and are below the regulation schedule. These levels need to stabilize. WCA-2A stages have dropped precipitously
(-0.62 feet), but remains well above regulation, and has been above regulation
since October 1, 2007 (i.e., almost 12 months). WCA-3A stage is unchanged and has been above
regulation since mid-July.
Everglades National Park (ENP)
and
Salinity trends across
Water Supply
Water levels declined
slightly across most of the District this past week. 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