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 4, 2007
SUBJECT: Weekly
Environmental Recommendation for Systems Operations
Recommendation
No
regulatory releases
to the south or estuaries are recommended.
Background
Well
below average rains likely across the
The upper Kissimmee Basin received 0.74
inches of rainfall over the last 7 days to bring the 30-day total to 2.99
inches (43% of average) and the lower basin received 1.90 inches to bring the
30-day total to 3.62 inches (58% of average) (Daily Rainfall Report for
09/04/07).
Stages in most of the upper basin lakes have been
stable over the last seven days. The
stage in
Snail kites continue to nest on
Flow has been reestablished to the
For the last week, the concentration of dissolved
oxygen in the river channel has remained above thresholds of concern with mean
daily values above 6 mg/L for the previous week.
According to the USACE
web site,
During August, 21 of the 27 water quality sampling
sites had sufficient water for sampling.
TSS values averaged 8 mg/L and TP values averaged 85 ppb.
In April, the last time the same 21 sites were sampled, mean TSS was 60 mg/L and mean TP was
175 ppb. No nearshore
bloom formation was observed during a helicopter flight on August 29 that
covered most of the lake shoreline. Data
from the August bloom buster survey are not yet available.
In the littoral zone, spikerush
(Eleocharis) is germinating in scattered
clumps along the west wall. About 50-100
acres of this species have become established in < 1 of very clear
water. This species provides habitat for
fish and wildlife. Approximately 10,000
acres of torpedograss have been treated this
summer. No regrowth
was reported at six sites that were treated this year and at two sites that
were treated in 2006. Dominant
vegetation at these sites included beakrush (Rhyncospora) and sedges. One site treated in 2005 had <25% control
and contained abundant torpedograss. Two other sites had >95% control and were
dominated by desirable wetland species including buttonbush (Cephalanthus), maidencane
(Panicum), arrowhead (Sagittaria)
and water lily (Nymphaea) as well as some
upland weeds.
St. Lucie Estuary
No releases occurred at S-80 over the past
week. Weekly average salinities at the
four monitoring sites in the St. Lucie are given below in parts per thousand (ppt).
|
Weekly Average Salinity (ppt) |
|
|
Sampling Site |
Surface |
Bottom |
Envelope |
|
5.2 |
5.9 |
|
HR1 (N. Fork) |
7.8 |
11.4 |
|
|
11.8 |
12.3 |
8.0 25.0 |
A1A Bridge |
19.5 |
26.0 |
20.0 31.0 |
Average weekly salinity in the estuary increased
slightly since the last report. Local
freshwater inflow continues to maintain surface salinity at both the
Seagrasses near the St. Lucie Inlet
were monitored on August 23. At site 2,
north of the inlet, Syringodium shoot counts
and canopy heights were similar to those observed last month. Many areas of the site are now densely
covered by Halophila johnsonii
and/or Halodule wrightii. Bottom salinity was 28 ppt
and visibility was fair to good (Secchi 0.8 m).
At Site 3, south of the
inlet. seagrass conditions were similar
to those observed last month: A dense,
healthy fringe of Halodule wrightii is present along the shoreline. Halophila johnsonii
and to a lesser extent Halophila decipiens and Halodule
wrightii are present in small patches within the
former Syringodium bed. Halodule wrightii
and Halophila johnsonii
are present along the offshore shoal.
The Syringodium bed at this site was
buried during the 2004 hurricanes and has not recovered. However, several small patches of Syringodium are currently present at the site.
Caloosahatchee Estuary
During the past week, discharge at S-79 averaged
266 cfs for the week.
Chloride concentration at the Olga Plant is presently 73 mg/l. Average salinity at the monitoring sites in
the upper Caloosahatchee Estuary decreased over the past week. Data for specific sites are given below in
parts per thousand (ppt).
|
Weekly Average Salinity (ppt) |
|||
Sampling Site |
Surface |
Bottom |
||
|
6.9 |
7.0 |
||
Rt. 31 Bridge |
NA |
8.4 |
||
I-75 Bridge |
7.1 |
10.6 |
||
|
11.7 * |
NA |
||
|
19.3 |
* based on three-day average. |
||
Shell Point |
30.5 |
32.3 |
While the weekly average salinity at
FWRI reports that no Karenia brevis, the
Water Conservation Areas
The EPA gauges indicated stable water
stages in WCA-1 and NE Shark River Slough, rising
water levels in WCA-2B, and falling water levels in WCA-2A, 3A and 3B.
At this time of year, falling stages in the
Water levels decreased for another week at all Everglades National Park
(ENP) platforms.
Depths at the Taylor Slough Bridge (TSB) water
level plunged by 5.6, another week of > 5 weekly recession. As a result, the TSB
stage is 1.5 ft lower than it was this time last year, and 2.5 ft lower than it
was this time two years ago. In the
panhandle region (EVER 6), water level was down by just over 2.25. Stage at Craighead Pond (CP) & to the
north in Shark River Sl. (P33) dropped by 1.2 &
1.4 over the 7 day period, respectively.
These recession rates are unusual for this time of the year when water
levels are typically still increasing.
One would think that salinity in the mangrove transition zone would rise
with falling stage. However, local
rainfall and possibly a long lag time between affects of stage change on
salinity, has prevented salinity from increasing last week. The platform at the mouth of Little Madeira
Bay saw salinity holding just below 20 psu for another
week. Salinity in the TR ponds remained very low all week (~ 1 psu at Pond 5 & Argyle Hendry). To the north and west,
Salinity is holding steady or increasing in the Bay regions of the
Park. Salinity readings in the
north-central Bay areas of Terrapin Bay and McCormick Creek increased through
much of last week, from the mid-20s towards 30 psu by
the weekend (likely, in part, to a mid-week Bay water flow reversal). In the central Bay,
Water Supply
Water levels in the upper and lower
Six out of eleven water supply risk measures are in
the high risk category this week including the projected Lake O Stage (SSM), the Palm Index for Tributary Conditions, the LOK Multi-Seasonal Net Inflow Forecast and Lower East Coast
Service Areas 1, 2 and 3.
Water Conservation Areas 1, 2A continue to be in
the low risk category. Water
Conservation Area 3A changed from low to medium risk this week. The CPC Precipitation Outlook remains at
low risk this week, along with the LOK Seasonal Net
Inflow forecast.
WSE
(
The current
CC: George
Horne