MEMORANDUM
TO: Chip Merriam, Deputy Executive
Director, Water Resources
FROM: SFWMD
Staff Environmental Advisory Team
DATE: April 29, 2008
SUBJECT: Weekly Environmental
Recommendation for Systems Operations
Recommendation
No Lake Okeechobee regulatory releases to the south or
estuaries are recommended.
Background
Scattered
showers and storms are south today, then dry and pleasant tonight through
Thursday morning. A cold front made its
way to the north
Over the last seven days, the upper Kissimmee Basin received 0
inches of rainfall to bring the 30 day total to 3.61 inches (149% of average),
and the lower basin received 0 inches to bring the 30 day total to 3.45 inches
(153% of average). During the last week,
releases were increased from East Lake Tohopekaliga
(S-59) to 160 cfs and from
In
the upper basin, snail kites continue to nest on East Lake Toho,
According
to the USACE web site,
April
water-quality monitoring results are now available. Seventeen of the 25 monitoring stations had
sufficient water for sampling. Total P
averaged 111 ppb lake wide (compared to 141 ppb in March) and 33 ppb at near
shore stations (compared to 81 ppb in March).
Total suspended solids (TSS) averaged 35 ppm lake wide (compared to 33 ppm
in March) and 6 ppm at near shore stations (compared
to 25 ppm in March).
Monthly
phytoplankton monitoring was performed on April 22. Six of nine sites had sufficient water for
sampling. Mean secchi
depth was 0.45 m (compared to 0.18 m in March).
Chlorophyll data are not yet available, but there was a surface bloom in
the Pahokee Marina and evidence of bloom formation at LZ40
(center of the lake). Samples were
collected for taxonomic analysis and a preliminary identification of Microcystis aeruginosa was
made by District staff. Microcystin concentrations were all at or below the
analytical limit of detection (0.2 ug L-1)
except for the Pahokee Marina sample which was 0.8 ug
L-1.
St. Lucie Estuary
There
were no releases through S-80 from C-44, S-49
from C-24, and S-48 from C-23 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 |
|
13.98 (11.09) |
15.26 (12.44) |
|
HR1 (N. Fork) |
17.57 ( 14.04) |
18.77 (16.87) |
|
|
16.76 (15.93) |
18.95 (18.02) |
8.0 – 25.0 |
A1A Bridge |
27.28 (24.66) |
29.16 (27.79) |
20.0 – 31.0 |
Average
salinity increased about 3 ppt in the South Fork and
North Fork, and about 1-2 ppt at
Caloosahatchee Estuary
No
discharge occurred through S-79 during the past week. An average weekly discharge of 302 cfs occurred at S-77.
The concentration of chlorides at the Olga Plant yesterday was 189 mg/l,
slightly up from 186 mg/l of last week.
Weekly average salinities for specific sites are given below in parts
per thousand (ppt).
Current weekly averages (in bold) may be compared to last week’s data
(in parenthesis).
|
Weekly Average Salinity (ppt) |
|
Sampling Site |
Surface |
Bottom |
|
13.77 ( 11.06) |
14.64 (11.73) |
Rt.
31 Bridge |
13.33 ( 10.89) |
NA (NA) |
I-75
Bridge |
NA ( NA ) |
17.41 (15.01) |
|
21.36 (19.40) |
22.23 (20.41) |
|
28.35 (26.95) |
28.98 (27.71) |
Shell
Point |
34.50 (33.40) |
35.22 (34.15) |
Average
salinities increased about 3 ppt in the upper
estuary, and 1-2 ppt in the lower estuary. Salinity at the
FWRI reports that no Karenia
brevis, the
Water Conservation Areas
Recession rates
in the conservation areas improved somewhat last week with low rainfall, high evapotranspiration and water management releases. However, recession rates are highly variable
across the region, best for wading birds
in parts of WCA-1, 3A, and 3B. WCA-2 recession rates are poor or fair Most of the conservation area water depths
remain well above the 1 foot maximum threshold for wading bird foraging. Stages
in WCA-1 have declined but are still above Regulation
Schedul, WCA-2A marsh
remains more than 1’ above regulation, and WCA-3A
stages continue to decline.
Very
little rain fell across Everglades National Park (ENP)
and
Salinity
is rising across the Bay and mangrove transition zone, but concentrations are
not abnormally high (i.e., this is typically the time of year when salinity
concentrations can rise rapidly with conditions of no or low rainfall or
incoming flow, and high evaporation). Near shore areas of Trout Creek,
Water Supply
Last week was relatively dry, so most water levels
decreased slightly across the District. Water
levels in the upper and lower
Six out the eleven water supply risk indicator
parameters are now in the “low” risk category, including the CPC Precipitation
Outlook, the Lake Okeechobee Seasonal and Multi-seasonal Net Inflow Forecast,
and Water Conservation Areas 1, 2A and 3A.
Four out the eleven water supply risk indicators
are now in the “medium” risk category, including the Palmer Index for Tributary
Conditions (dry) and the LEC Service Areas 1, 2 and
3.
The only risk measure that is in the “high” risk
category is the projected Lake Okeechobee Stage (water restriction zone).
WSE
(
The
current
CC: George Horne