MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       February 26, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

No Lake Okeechobee regulatory releases to the south or estuaries are recommended.

 

Background

 

Some showers and thunderstorms.  Moisture is beginning to return to the area ahead of an approaching cold front.  Expect the front to move into north central Florida by sunset, Lake Okeechobee after midnight, and then be near the southern end of the District Wednesday morning.  Afternoon heating will generate some scattered showers activity over the interior and east today and then stronger thunderstorm activity will move into northern areas with the front this evening.  As the front moves southward overnight, shower coverage and intensity will decrease.  Scattered shower activity will persist south Wednesday morning, then dry conditions will move over the District and persist the remainder of the week.  Another cold front is expected to bring another round of rain next Tuesday.  The next ten days precipitation outlook is near average with moderate confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received approximately 0.37 inches of rainfall to raise the 117-day total to 4.96 inches (51% of average) and the lower basin received 0.58 inches to raise the 117-day total to 4.42 inches (57% of average).  Water levels in the upper basin lakes are at or below their regulation schedules.

 

Lake Kissimmee (S-65) continued discharging approximately 250 cfs to the Kissimmee River.  Releases of 900 cfs are being made from Lake Toho (S-61) and of 200 cfs from East Lake Toho to allow a more gradual water level recession during the snail kite nesting season.  No other releases are being made in the upper basin.

 

In the upper basin, snail kites continue to nest on East Lake Toho and Lake Toho.  Several additional nests have been reported in Lake Toho.  A whooping crane nest with eggs has been reported on Lake Kissimmee.   Flow has been reestablished to the Kissimmee River for 216 days (S-65 re-opened on 07/18/07).  Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 5.5 mg/L to 8.6 mg/L with an average of 7.3 mg/L.

 

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.13’ NGVD, which is the same as a week ago and 0.03’ higher than a month ago.  The current stage is 1.15’ lower than it was a year ago and 4.48’ below its historical average for this time of year.  Reported inflows cfs include the Kissimmee River (~250 cfs), the S77 (~150 cfs), and the L8 at Canal Point (~600 cfs).  No outflows are reported.

 

Monthly phytoplankton bloom monitoring was conducted on Monday February 25.  Six of nine sites had sufficient water to access for sampling.  No blooms were observed.  Water clarity was typical for this time of year with secchi depths ranging from 0.20-0.75 m.  Average secchi depth was 0.50, which is the highest value for February since before the hurricanes in 2004.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  No discharge occurred at S-97 on the C-23 Canal or at S-49 on the C-24 canal.  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

Palm City Bridge (S. Fork)

10.6 (9.7)

13.1 (12.7)

 

HR1 (N. Fork)

 15.9 (16.9)

18.2 (18.2)

 

Roosevelt Bridge

 21.3 (21.2)

21.7 (22.0)

8.0 – 25.0

A1A Bridge

 27.1 (27.6)

28.5 (28.7)

20.0 – 31.0

 

Average salinity changed very little (< 1.0 ppt) throughout the estuary.  Both the surface and bottom salinity are in the preferred range at the Roosevelt Bridge, and at the A1A Bridge.  Based on the salinity tolerances of the oyster, Crassostrea virginica, salinity conditions in the estuary are good.   The current surface salinity of 21.3 ppt at the Roosevelt Bridge is 6.7 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

 

Caloosahatchee Estuary

 

Discharge at S-79 averaged 55 cfs for the week, down from previous week’s 150 cfs.   The 30-day average is 78 cfs. Freshwater flow back into the Lake from C-43, through S-77, averaged 156 cfs during the last week.  The concentration of chlorides at the Olga Plant were stable during the last week , with 171 mg/l reported last Sunday.  In general, average salinity declined over the past week, most notably at Ft. Myers and upstream, with the largest change of about 2.0 ppt occurring near S-79 where discharges occurred.  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

Franklin Locks (S-79)

 14.2 (16.7)

 14.5 (16.5)

Rt. 31 Bridge

15.1 (16.8)

17.1 (19.0 )

I-75 Bridge

NA (NA)

 18.6 (20.2)

Ft. Myers Yacht Basin

 22.5 (23.6)

 22.5 (23.8)

Cape Coral Bridge

 27.1 (26.9)

 30.4 (30.7)

Shell Point

34.2 (34.2)

 35.6 (35.5)

 

Salinity at the Ft. Myers surface sensor remains above the 1-day MFL maximum criterion of 20 ppt.  The current surface salinity of 14.2 ppt at S-79 is 5.8 ppt below the maximum weekly average of 20.0 ppt achieved in May 2001 during the 2000 – 2001 drought.  Salinity at the Cape Coral Bridge is near (surface) or above (bottom) the upper limit of the optimal range for the oyster, Crassostrea virginica.  However, salinity for seagrass in the area downstream of Cape Coral sensor is good.

 

In summary, conditions in the upper estuary east of Ft. Myers are poor due to high salinity.  Based on the tolerances of oysters, salinity conditions downstream of Cape Coral are fair.

 

FWRI reports that 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

 

Dry season recession rates were mixed in the Greater Everglades.  After last week’s reversals, most of the recession rates returned to good or fair, although rapid reversals of 0.31’ in WCA-2A and 0.19’ at Stage 63 in northern WCA-3A represent poor dry season events.  After the previous week’s heavy rainfalls, water depths in most of the conservation areas rose to levels too deep for foraging (deeper than 1’), particularly in WCA-1, 2, and southern WCA-3A (with poor depth ratings).  Water depths in northern WCA-3A and southern WCA-3B are the exceptions, with a rating of good (0.1’-0.8’).  Water depths range from 0.4’ to 2.0’ at all reporting gauges.  Stages in WCA-1 and WCA-3 are about at regulation, while the WCA-2A marsh has risen higher above regulation than it was last week

 

Everglades National Park

 

Rainfall was patchy last week across Everglades National Park (ENP) and Florida Bay.  Marine and wetland platforms in ENP recorded between 0”–1.0” of precipitation.  The ENP basin spatially-averaged RAINDAR similarly reflects this total at 0.13”.

 

Last week’s water level trends for ENP wetlands were mixed.  Shark River Slough (station P33) and southern Taylor Slough (at Craighead Pond) water levels declined by 0.8” and 2”, respectively, for the week.  Water depths rose nearly 0.5” in the ENP panhandle (station EVER6).  Stages rose through the early part of last week at Craighead Pond, ending up at just 0.1” weekly increase.

 

Salinity concentrations remained generally stable again in Florida Bay last week.  Salinity remained in the mid- to upper 20s at Trout Creek.  At the mouth of Taylor River, salinity remained just above 20 psu for another week.  Salinity concentrations in the Taylor ponds remained in the single digits last week; the 30 day moving average concentration at Argyle Hendry (station TR, used to track FL Bay MFL criterion) was at 7.4 psu as of Sunday, 2/24.  Salinity concentrations were in the low to mid-20s last week at Little Madeira Bay and in the north-central Bay areas of McCormick Creek and Terrapin BayWhipray Basin salinity remained near 33 psu throughout the week.  As a whole these salinity concentrations are still near seasonal norms.  The exception to this trend is out west, in the Shark River Slough outflow at Tarpon Bay, where salinity still remains above its seasonal average, measuring near 15 psu as of Sunday 2/24; this is not surprising given the low water levels in SRS.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast remain slightly below their historical average conditions for this time of year.  Water levels in the Lower East Coast are still near or slightly above their historical averages and most wells recorded modest increases in water levels this past week.  Water levels in the Upper East Coast remain well above their historic averages.  Surface and groundwater levels in Water Conservation Areas 1 and 2 are now near their historic averages as a result of local rainfall and continue to rebound as a result of recent rainfall.  Water levels in WCA 3A have rebounded to near their historic averages this week.  Water levels in the southernmost portion of Miami-Dade County are now near their average historic conditions.

Six out of eleven water supply risk measures are in the “high” risk category including the projected Lake Okeechobee Stage (SSM), the Palmer Index for Tributary Conditions, the CPC Precipitation Outlook, and Lower East Coast Service Areas 1, 2 and 3.

 

The LOK Seasonal Net Inflow and the LOK Multi-Seasonal Net Inflow Forecasts remain at “medium” risk this week.  Water Conservation Areas 1, 2A and 3A continue to be in the “low” risk category.

 

Chlorides at the Olga WTP on the Caloosahatchee River are now at 171 ppm and the plant is operational.

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake Okeechobee stage remains in the Water Shortage Management zone and is unlikely to move back into Zone E in the next several months during the persistent La Niña climactic conditions.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CC:   George Horne