MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       May 6, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Warm and mostly dry.  High pressure is building over the area and will bring dry conditions today and Wednesday.  A cold front is forecast to push into north Florida Friday.  Moisture ahead of this system will allow widely scattered shower activity to pop up mainly east and north Thursday.  Scattered showers will then develop north and east Friday and then east Saturday.  The next ten days precipitation outlook is below average with moderate confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.10 inches of rainfall to bring the 30 day total to 2.81 inches (113% of average), and the lower basin received 0.02 inches to bring the 30 day total to 2.74 inches (115% of average).

 

During the last week, releases were either increased or initiated for several of the upper basin lakes.  Releases from Lakes Hart and Mary Jane (S-62) began last week at about 100 cfs.  Releases from East Lake Tohopekaliga (S-59) increased from 160 cfs to 250 cfs.  Releases from Lake Tohopekaliga (S-61) increased from 600 cfs to 800 cfs.  Releases from the Alligator Chain (S-60) began at 50 cfs.  Releases from Lake Kissimmee (S-65) were decreased from 1100 cfs to 700 cfs.

 

The vegetation removal project on Lake Gentry ended last week.

 

Hydrilla treatment continues in Lake Cypress.  Treatment with a systemic herbicide began on April 7th during a period of no inflow from Lake Toho (S-61).  Since inflow has resumed, herbicide concentrations are being maintained in the desired range with an injector located in the inflow from Lake Toho.  In the upper basin, snail kites continue to nest on East Lake Toho, Lake Toho, and Lake Kissimmee.  Nests on Lake Toho continue to represent a large fraction of the total number of snail kite nests in Florida.

 

Flow has been reestablished to the Kissimmee River for 286 days (S-65 re-opened on 07/18/07).  Flow is approximately 700 cfs at S65, 600 cfs at S-65C, and 750 cfs at S-65E.  With the decreased inflow from the upper basin, water levels continue to decline across the Kissimmee River Restoration Project.  At PC62, near the upstream end of the Phase I area, water level peaked at 39.9 feet on April 10 and has fallen approximately 4 feet.  Currently, the water surface elevation decreases by 2 feet from the upstream end to the downstream end of the restoration project.  Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 3.7 mg/L to 7.9 mg/L with an average of 5.8 mg/L, which is almost identical to last week.

A recommendation was made on Friday (May 2, 2008) to begin lowering the water levels (headwater stage) at S-65C from the current elevation of 35 feet to 33 feet by June 1 for environmental purposes.  Healthy wetland plant communities require fluctuating water levels and periodic drying.  Since Phase I of the Kissimmee River Restoration Project was completed in 2001, water levels have been varied to improve conditions at the lower end of Pool C that ordinarily would experience stabilized water levels.  The water levels have not decreased to 33 feet since 2003, and there are indications of problems, especially with mat-forming species.  Current conditions of moderate inflow at S-65 and low rainfall will favor lowering water levels.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.11’ NGVD, which is 0.20’ lower than a week ago and 0.21’ lower than a month ago.  The current stage is 0.62’ higher than it was a year ago and 3.47’ below its historical average for this time of year.  Reported inflows include ~760 cfs from the Kissimmee River.  Outflows include ~330 cfs through the S352 and ~365 cfs through the S77.

 

An apple snail egg survey was initiated along the northwestern and western littoral zones and in Fisheating Bay during the last week of April.  Approximately 80 of a total of 128 transects have been sampled, and 17 clutches of apple snail eggs were found on 2 adjacent transects in the northwestern region between the Indian Prairie Canal and Tinhouse Cove.  No clutches were found along the western littoral zone and the remaining transects, all located in the Fisheating Bay area, will be completed next week.  Egg surveys will continue each month through the summer to determine the distribution of apple snails across the littoral zone after 2 years of drought.

 

Bloom sites that were reported on last week (Pahokee Marina and LZ40 in the center of the lake) were sampled again at the end of last week.  Chlorophyll and toxin data are not yet available, but the blooms at both sites have largely dissipated.

 

A wildfire continues to burn in the littoral zone near Observation Island on the southwest side of the lake.  At least 3500 acres have burned; arson is believed to be the cause.

 

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

Palm City Bridge (S. Fork)

15.16 (13.98)

16.13 (15.26)

 

HR1 (N. Fork)

16.88 (17.57)

18.14 (18.77)

 

Roosevelt Bridge

16.07 (16.76)

18.81 (18.95)

8.0 – 25.0

A1A Bridge

26.56 (27.28)

30.07 (29.16)

20.0 – 31.0

 

Average salinity increased about 1 ppt in the South Fork and North Fork, and remained about the same at Roosevelt Bridge and A1A Bridge during the past week.  Both the surface and bottom salinity are in the preferred range at the Roosevelt Bridge and at the A1A Bridge.  Salinity conditions in the estuary are considered good, based on the salinity preference of the oyster, Crassostrea virginica, at Roosevelt Bridge.  The current surface salinity of 16.0 ppt at the Roosevelt Bridge is 12 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

Caloosahatchee Estuary

 

The flow data at the structures along C-43 were available for only three days during the last week.  There was no flow through S-79 at the beginning of the reporting period and the gates were closed Monday May 6th.  As of May 2nd, the prior 30-day average flow from S-79 was 130 cfs.  During the beginning of the week, flows at S-77 from Lake Okeechobee were 81 and 411 cfs. S-77 flow yesterday was 364 cfs.  At S-78, flows were 59 and 129 cfs at the beginning of this reporting period and 36 cfs yesterday.  The concentration of chlorides at the Olga Plant was 203 ppm yesterday, up from 192 ppm at the beginning of this reporting period.  Current weekly averages (in bold) may be compared to last week’s data (in parenthesis).  Averages are based on data available for 5 of the 7 days.

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

15.74 ( 13.77)

16.45 (14.64)

Rt. 31 Bridge

15.77 (13.33)

17.68 (NA)

I-75 Bridge

16.47 ( NA )

18.68 (17.41)

Ft. Myers Yacht Basin

22.29 (21.36)

23.16 (22.23)

Cape Coral Bridge

29.36 (28.35)

29.51 (28.98)

Shell Point

34.55 (34.50)

35.36 (35.22)

 

Average salinities increased approximately 2 ppt in the upper estuary, about 1 ppt in the lower estuary at Cape Coral, and stayed the same at Shell Point.  Salinity at the Ft. Myers surface sensor was above the 1-day MFL criterion of 20 ppt.  The current surface salinity of 15.7 ppt at S-79 is 4.3 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 above the optimal range for the oyster, Crassostrea virginica.  Conditions in the upper estuary east of Ft. Myers are poor due to high salinity.  Conditions in the lower estuary downstream of Cape Coral are fair considering the combine salinity preference of oysters and seagrasses.

 

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

 

Recession rates were excellent in almost all the WCA’s.  Only NE Shark River Slough and WCA-3B had rainfall quantities sufficient to cause slight reversals.  However, large regions of the WCA’s continue to exhibit depths greater than 1 foot.  Depths greater than one foot are inhospitable for wading bird foraging.  Stages in WCA-1 have declined and are at Regulation, WCA-2A marsh remains well above regulation and WCA-3A stages are within zone E1 of the regulation schedule for protection of the Cape Sable Seaside Sparrow.

 

Everglades National Park

 

Patterns for Everglades National Park (ENP) wetland water levels followed those for rainfall (areas that saw rain were up, while other areas without precipitation declined).  Nearly 1.5” of rainfall in Shark River Slough (station P33) allowed water levels here to increase for the week by 1.3”.  Fueled by low rain & high evapotranspiration, water level was down for a second week by nearly 5” over the 7 day period at Taylor Slough. Bridge (not an unusual recession rate at this station).  The southern part of Taylor Slough (at Craighead Pond) also posted declining water levels, down by 1.7” for the 7 day period.

 

Salinity in Florida Bay increased slightly last week.  Salinity rose into the mid-30s at Trout Creek and into the lower 30s at the mouths of Taylor River & L. Madeira Bay.  In the Taylor ponds, salinity approached 30 psu at Pond 5 (USGS station) and Argyle Hendry (ENP station TR).  As of Sunday, 5/4, the 30 day moving average concentration at TR (used for tracking the Florida Bay MFL criterion) was at 22.4 psu (up from 20.3 psu last week, and while not unseasonably high, the highest concentration we have seen yet this dry season).  Salinity also increased in the northcentral Bay areas of McCormick Creek and Terrapin Bay, where concentrations once rose into the upper-30s by the week’s end.  At the central Bay station in Whipray Basin salinity held in the mid-upper 30s for another week, though in shallower areas to the northwest (in Rankin Lake), our Dataflow field crew measured concentrations closer to 50 psu last week.  These salinity concentrations across Florida Bay are near seasonal norm.  Despite being above average for much of the dry season, salinity in the upstream reaches of Shark River (Tarpon Bay platform) measured near its seasonal norm (mid-teens) for another week.

 

Wildlife

 

The monthly colony survey revealed that the recent improvements in hydrologic conditions have not initiated a late surge in nesting activity.  A total of 1195 nests (795 egrets and 400 White Ibis nests) were counted.  This is almost double last month’s count but considerably lower than both the May 2006 and May 2007 counts when 36625 and 7170 nests were observed, respectively.  Most nesting activity is in the Refuge.

 

Most areas of the WCAs supported low numbers of foraging birds. Very few birds were seen in WCA-3A or WCA-2A and most activity was seen in the northern Refuge

 

Water Supply

 

Last week was relatively dry, so most water levels decreased slightly across the District.  Water levels in the upper and lower Kissimmee Basin are now near their historical average conditions for this time of year.  Water levels in the Lower West Coast are a “mixed bag” of average to slightly higher than historical averages, depending on the degree of confinement of the aquifers.  Water levels in the Lower East Coast are near or their historical averages.  Water levels in the Upper East Coast remain well above their historic averages although they declined slightly this week.  Surface and groundwater levels in Water Conservation Areas 1, 2 and 3 are now near or slightly above their historic averages.  Water levels in the southernmost portion of Miami-Dade County are now near their average historic conditions.

 

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).

 

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 during the persistent La Niña climactic conditions.

 

CC:   George Horne