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: July 1,
2008
SUBJECT: Weekly
Environmental Recommendation for Systems Operations
Recommendation
No
Lake Okeechobee regulatory releases to
the south or estuaries are recommended.
Background
Numerous showers and storms today.
There are several favorable elements for thunderstorm development
evident in this morning’s analysis.
Light steering winds make it somewhat problematic in determining a
focus; however, there should be a tendency for afternoon through early evening
activity to align from Collier
County northeastward
through St. Lucie County. Upper level
winds become a little less favorable on Wednesday while the east coast seabreeze makes a little more inland penetration. This should result in some decrease in storm
coverage with a focus west through north of the Lake
tomorrow afternoon/evening. Upper level
winds begin to become more favorable again for storm development late Thursday
and especially Friday, so look for activity to increase by Friday. Longer term, there is some evidence the
atmosphere will begin to transition to a more typical July pattern in about
7-10 days. If so, overall rainfall would
also decrease. . The next ten days precipitation outlook is average
with low confidence.
Kissimmee Watershed
Over the last
seven days, the upper Kissimmee Basin received 2.12 inches of rainfall to bring
the 30 day total to 7.63 inches (105% of average), and the lower basin received
2.09 inches to bring the 30 day total to 7.37 inches (106% of average) (Daily
Rainfall Report 6/30/08).
With the
continued rainfall, water levels are rising in all of the lakes, except Lake Kissimmee.
All lakes remain below regulation schedule, but several are approaching their
regulation schedule elevation for summer.
In the upper basin, snail
kites continue to nest on East Lake Toho, Lake
Toho, and Lake Kissimmee.
Flow has been
reestablished to the Kissimmee River for 350
days (S-65 re-opened on 07/18/07). Flow is approximately 200 cfs at S65. River water levels
within the Kissimmee River Restoration Project area have been rising and
falling in response to rainfall events.
Dissolved oxygen
concentrations in the river channel of the Kissimmee River
are beginning to fall below thresholds of concern temporarily.
Concentrations ranged from 0.1 mg/L to 5.4 mg/L and averaged of 4.2 mg/L.
Lake Okeechobee
According to the USACE web site, Lake Okeechobee
stage is 9.65’ NGVD, which is 0.33’ higher than a
week ago and 0.05’ higher than a month ago.
The current stage is 0.79’ higher than it was a year ago, 3.87’ below
the historical average for this date, and 2.62’ below the simulated historical
average for the current regulation schedule (LORS2008). Total reported inflows are approximately 2314
cfs and include 352 cfs
from the Kissimmee River, 1279 cfs through the S71, 94 cfs
through the S84, and 589 cfs from the L8 at Canal
Point. No flows are reported for S308
and S77, and no outflows are reported.
The third monthly apple-snail
egg survey was conducted along transects across the outer (flooded) edge of the
littoral zone on June 25th.
Shallow water (<10 cm) limited the survey to the lakeward
edge of the transects.
No apple snail eggs were found using this truncated survey method. Previous research indicates that apple snails
do not lay eggs in water this shallow.
Surveys during the previous two months recorded only 29 egg clusters
along 3 adjacent transects near Indian
Prairie Canal. While additional remnant apple snail
populations may be located as larger areas of the littoral zone reflood, findings to date indicate that they will be sparse
and widely scattered.
St. Lucie Estuary
There were no releases
through S-80 from C-44 over the past week.
An average discharge of 125.52 cfs through
S-48 from C-23 and 90.32 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). The surface salinity at A1A
Bridge is a three- day average.
|
Weekly Average Salinity
(ppt)
|
|
Sampling Site
|
Surface
|
Bottom
|
Envelope
|
Palm City Bridge (S. Fork)
|
13.15 (17.42)
|
15.43
(19.76)
|
|
HR1 (N. Fork)
|
14.72 (17.66)
|
17.95 (22.02)
|
|
Roosevelt Bridge
|
18.30 (21.51)
|
19.15 (23.18)
|
8.0 – 25.0
|
A1A Bridge
|
24.68
(29.48)
|
NA (NA)
|
20.0 – 31.0
|
Compared with salinities of
the previous week, average salinity decreased throughout the estuary due to
local runoff. Salinity declined between
3 ppt and 5 ppt depending
on location and depth. Salinity at Roosevelt Bridge and A1A
Bridge are within the preferred range.
Salinity conditions in the estuary are considered good, based on the salinity
preference of the oyster, Crassostrea virginica. The
current surface salinity of 18 ppt at the Roosevelt Bridge is 10 ppt
below the maximum weekly average of 28.0 ppt achieved
in May 2001 during the 2000 – 2001 drought.
Caloosahatchee Estuary
An average weekly discharge
of 1039 cfs occurred at S-79. The concentration of chlorides at the Olga
Plant was 130 ppm yesterday, down from 228 ppm in the beginning of this reporting period. Current weekly averages (in bold) may be
compared to last week’s data (in parenthesis).
|
Weekly Average Salinity
(ppt)
|
Sampling Site
|
Surface
|
Bottom
|
Franklin Locks (S-79)
|
7.79 (13.53)
|
8.15
(14.80)
|
Rt. 31 Bridge
|
7.96
(16.8)
|
11.74
(20.10)
|
I-75 Bridge
|
10.08
(17.96)
|
15.71
(20.76)
|
Ft. Myers Yacht Basin
|
18.31
(23.75)
|
21.32
(24.16)
|
Cape Coral Bridge
|
26.68
(28.81)
|
26.99
(29.21)
|
Shell Point
|
33.03
(34.37)
|
33.30
(34.42)
|
Compared to last week,
average salinities dropped between 3 ppt and 8 ppt depending on depth and location. Average salinity at the Ft. Myers
surface sensor was 18 ppt, which is 2 ppt below the 1-day MFL criterion
of 20 ppt. The
current surface salinity of 8 ppt at S-79 is 12 ppt below the maximum weekly average of 20.0 ppt achieved in May 2001 during the 2000 – 2001 drought. Salinity at
Shell Point and the Cape Coral
Bridge is within the
optimal range for the oyster, Crassostrea virginica.
Salinity conditions in the upper estuary east of Ft. Myers
have improved. Conditions in the lower
estuary downstream of Cape Coral
are good considering the combine salinity preference of oysters and seagrasses.
No Karenia brevis, the
Florida red
tide organism, was detected this week in water samples collected alongshore
between Pinellas and Collier counties.
Water Conservation
Areas
Good recession
rates occurred this past week in quite a few locations throughout the Everglades.
However, only two locations had both good recession rates and depths
suitable for wading bird foraging (i.e., < 1.0 ft); one was the northern
regions of WCA-1 and the other was WCA-3B. Depths in WCA-2A continue to be below 1 ft however, reversals have
been the trend in WCA-2A for the last three weeks.
Everglades National Park
Weekly rainfall accumulations
across Everglades National Park (ENP) ranged from
0.1” – 3.7”, with higher totals picked up along the eastern Park boundary. Spatially variable rainfall produced mixed
trends for ENP wetland water levels. Water level actually dropped in Shark River
Slough (station P33) by 0.6” for the week.
This is in contrast to Taylor
Slough Bridge,
where water levels increased by nearly 11” (after a 16” increase last week),
and are finally approaching average conditions for this time of year (near
ground surface). By comparison, stage
increases were more modest in the panhandle (station EVER6,
7 d increase of 1.4”) and in the southern part of Taylor Slough at Craighead
Pond (weekly increase of 2”). Moderate
flows (< 200 cfs) from S332D
continue to be delivered towards Taylor Slough, while higher flows (300 - 1000 cfs) have been recorded through the S18C
panhandle spillway since 6/19.
Salinity trends across Florida Bay were mixed last week. USGS platforms at
the eastern creek mouths (W. Highway, Stillwater,
Trout) recorded declining salinity over the past week,
from the mid-30s down into the teens or mid-20s by Sunday, 6/29. However, salinity in the
eastern Bay proper (e.g., Duck Key, L. Madeira Bay mouth), held in the mid-30s
for another week. Salinity
concentrations have been stable in creeks to the west (Taylor River, Mud Creek),
further suggesting (as CP stage has also shown) that Taylor Slough will require
a good bit of re-hydration before flows make their way south towards the
Bay. The Taylor River (TR) 30 day moving average salinity concentration (used for
tracking the FL Bay MFL criterion) dropped to 31.7 psu as of Sunday, 6/29 (down a bit from last week’s reading
of 34.5 psu). Salinity
remained stable in the northcentral Bay
areas of McCormick Creek. & Terrapin
Bay (in the mid-30s) and at the
central Bay station in Whipray Basin
(in the mid 40s). In the upstream
reaches of Shark River
(Tarpon Bay platform), on the other hand,
salinity dropped into the single digits last week (down to 6 psu as of Sunday, 6/29), slowly approaching seasonal
average concentrations.
Water Supply
Although there was some rain
last week, most of the water fell south of Lake Okeechobee. Water levels in the upper and lower Kissimmee Basin are now well below their average
conditions for this time of year, and approaching their historic lows. Water levels in the Lower
West Coast are now below historical averages, although there was
some continued rebound this week. Water
levels in the Lower East Coast are now near
historical averages. Water levels in the
Upper East Coast are still slightly above their
historic averages, although they also have been declining. Surface and groundwater levels in Water
Conservation Areas 1, 2 and 3 are now near their historic averages, most wells
enjoyed a rebound this week. Water
levels in the southernmost portion of Miami-Dade County
are now near their historic average levels and rebounded sharply this week.
There was also some
improvement in the water supply risk indicators since last week. Six out of 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 Palmer
Index for Tributary Conditions and LEC Service Areas
1, 2 and 3.
Only one risk measure is now
in the “high” risk category, the projected Lake Okeechobee Stage (Water
Shortage Management Band).
LORS2008 (Lake Okeechobee
Regulation Schedule)
The current Lake
Okeechobee stage remains in the Water Shortage Management zone and
is unlikely to move back into the Operational Band in the next several months.
CC: George Horne