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 9, 2008
SUBJECT: Weekly
Environmental Recommendation for Systems Operations
Recommendation
Inflows from the tributary
basins have continued to taper off but remain in the very wet tributary
hydrologic conditions. Stages in Lake
Okeechobee (
Background
Moderate rainfall mainly south through Wednesday.
Hurricane Ike is moving westward through western
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 0.5 – 1.0 ft
over the last week. However, some areas
are still as deep as 6.8 feet. From 9/02/08 to 9/9/08 dissolved oxygen
concentrations in the
According to the USACE web
site,
St. Lucie Estuary
During the last week, an
average discharge of 1912 cfs occurred at S-80 from
C-44 and 879 cfs at S308. An average discharge of 666 cfs through S-48 from
C-23 and 818 cfs through S-49 from C-24 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 |
|
0.22 (0.17)
|
0.22
(0.17) |
|
HR1 (N. Fork) |
0.29 (0.15) |
0.47 (0.17) |
|
|
0.92 (0.20) |
1.66 (0.20) |
8.0 – 25.0 |
A1A Bridge |
6.48
(2.87) |
16.66 (9.75) |
20.0 – 31.0 |
Compared with salinities of
the previous week, average salinity in the estuary increased only slightly in
the upper estuary (<1 ppt) to about 4-7 ppt in the lower estuary at A1A Bridge. 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 6191 cfs occurred at S-79 and 2136 cfs at S-77. The
concentration of chlorides at the Olga Plant was 40 ppm
yesterday, up from 30 ppm at the beginning of this
reporting period. An average discharge
of 3708 cfs occurred at S-78 over the past week.
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 |
|
0.21 (0.16) |
0.22
(0.15) |
Rt. 31 Bridge |
0.21
(0.16) |
NR (NR) |
I-75 Bridge |
0.24
(0.20) |
0.22
(0.18) |
|
0.23 (0.19) |
0.23 (0.19) |
|
1.15 (0.54) |
1.60 (1.13) |
Shell Point |
11.16 (7.69) |
16.62 (11.45) |
In the estuary, freshwater
conditions extend from S-79 downstream to
Salinity at
No Karenia brevis, the
Water Conservation
Areas
Water depths in
the Greater Everglades (GE) have increased by 1 foot during the last month
almost everywhere. Depths now range from
a high of 4.28 feet in WCA-2B to a low of 1.5 foot in NE Shark River Slough.
The Greater Everglades 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 42 days above the tree island threshold.
WCA-1 has dropped
below the regulation schedule. All the
other WCA stages are above regulation, especially WCA-2A, which has been above
regulation since Oct. 1, 2007 (i.e., the last 11 months). It is not possible to
restore drowned tree islands in WCA-2A under this hydrologic regime.
Stages in Everglades National
Park (ENP) wetlands declined last week.
Water levels were down by approx. 1.9 inches last week in Shark River
Slough (station P33), and by just over 1 inch in other areas of the Park (ENP
panhandle, Taylor Slough Bridge, & Craighead Pond).
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 and Hanna. Water levels in the upper and lower
Surface and groundwater
levels in Water Conservation Areas 1, 2 and 3 are now slightly above their
historic averages this week – the highest recorded levels were within Water
Conservation Area 2.
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 as a result of the water restrictions that are now in
place.
LORS2008 (
Stages in
CC: George Horne