M E M O R A N D U M

 

FROM:            SFWMD Staff Environmental Advisory Team

 

DATE:            May 14, 2008

 

TO:                 Chip Merriam, Deputy Executive Director, Water Resources

 

SUBJECT:     Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Some limited shower activity this weekend.  Mostly dry conditions are expected today and Thursday as high pressure builds in over the area.  Some moisture and isolated to widely scattered shower activity will return Thursday and Friday as winds become more southerly ahead of the next frontal system.  This next front will push into north Florida Friday evening and then into south Florida by Saturday evening.  Scattered afternoon shower activity will affect mainly eastern areas Saturday and Sunday. The next ten days precipitation outlook is below average with moderate confidence.

 

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.00 inches of rainfall to bring the 30 day total to 0.14 inches (5% of average), and the lower basin received 0.04 inches to bring the 30 day total to 0.08 inches (3% of average).

 

During the last week, releases from the upper basin lakes were adjusted to allow water levels to decline with the regulation schedules.  Releases from East Lake Tohopekaliga (S-59) continued at 250 cfs. Releases from Lake Tohopekaliga (S-61) decreased from 800 cfs to 600 cfs.  Releases from the Alligator Chain (S-60) continued at 50 cfs.  Releases from Lake Gentry were increased to 100 cfs.  Releases from Lake Kissimmee (S-65) were decreased from 700 cfs to 500 cfs.    

 

The Florida Fish and Wildlife Conservation Commission reports that the Lake Gentry project was completed last week with the removal of 20 acres of cattail and primrose willow tussocks from along the shoreline to upland disposal sites. 

 

In Lake Tohopekaliga, 4,000 acres hydrilla (of 12,000 acres currently estimated on the lake) were treated with a contact herbicide two weeks ago.  Hydrilla in the treatment area is showing signs of herbicide effects.  In Lake Cypress, hydrilla treatment with a systemic herbicide (initiated on April 7) continues.        

 

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 293 days (S-65 re-opened on 07/18/07).  Flow is approximately 500 cfs at S65 and at S-65C.  With the decreased inflow from the upper basin, water levels continue to decline across the Kissimmee River Restoration Project. The water level at PC62, near the upstream end of the Phase I area, has fallen about 0.5 ft in the last week to 36.38 feet.  The headwater stage at S-65C has decreased to 34.45 feet, so that the water surface elevation decreases by 1.93 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 3.0 mg/L to 9.2 mg/L with an average of 5.8 mg/L. 

 

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.98’ NGVD, which is 0.13’ lower than a week ago and 0.53’ lower than a month ago.  The current stage is 0.66’ higher than it was a year ago and 3.44’ below its historical average for this time of year.  Reported inflows include 672 cfs from the Kissimmee River.  Outflows include 316 cfs through the S352. 

 

The monthly submerged-aquatic-vegetation (SAV) survey was completed last week.   Water clarity was generally conducive to plant growth with secchi depths greater than 50% of total depths at 30 of the 31 sites sampled.  The macroalga Chara remains the dominant SAV species and was found at 10 of the 30 sites (6 of the 10 sites were in the south end of the lake).  One species of vascular SAV, Vallisneria americana, continues to be present in very low density at a few sites around King’s Bar on the northern shoreline and a few sites along the western shoreline. Most of the Vallisneria is still short but there were several sites along the western shoreline where it was 15 to 20 cm tall and very dense with reproductive structures present.  Many patches of southern naiad (Najas guadalupensis) also were observed in very low density along the western shoreline.

     

The algal bloom reported to be developing at several locations across the lake has disappeared and field reports from last week indicate that it has not reformed.  Cyanobacterial toxin data were collected on May 1 as the bloom dissipated.  A microcystin level of 1.2 ppb was reported at the Pahokee Marina, and other sites had toxin levels below detection (<0.2 ppb).  Chlorophyll data from the bloom sampling are not yet available.  

 

A wildfire continues to burn in the littoral zone in the southwest corner of the lake.  Roughly 9000-10,000 acres have now burned.  The fire is 50% contained and its rate of spread has slowed.  However, burning muck will continue to be an issue until the area experiences significant rainfall.

 

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)

 16.60 (15.16)

17.99 (16.13)

 

HR1 (N. Fork)

  18.26 (16.88)

 20.64 (18.14)

 

Roosevelt Bridge

17.82 (16.07)

19.88 (18.81)

8.0 – 25.0

A1A Bridge

 26.98 (26.56)

30.19 (30.07)

20.0 – 31.0

 

 

Average salinity increased about 1.5 – 2  ppt in the South Fork, North Fork, and Roosevelt Bridge and only slightly at A1A Bridge. 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 17.8 ppt at the Roosevelt Bridge is 10.2 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

 

Caloosahatchee Estuary

 

No discharge occurred through S-79 during the past week.  An average weekly discharge of 420 cfs occurred at S-77and 75 cfs at S-78.  The concentration of chlorides at the Olga Plant was 276 ppm yesterday, up from 203 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)

 14.97 ( 16.12)

15.73 (16.80)

Rt. 31 Bridge

17.52 (15.90)

 17.79 (18.07)

I-75 Bridge

  18.60 ( 16.59 )

 19.23 (18.70)

Ft. Myers Yacht Basin

  23.60 (22.57)

 23.70 (23.21)

Cape Coral Bridge

  30.73 (29.47)

31.10 (29.85)

Shell Point

  35.38 (34.74)

 36.08 (35.54)

 

Average salinities increased about 1-2 ppt except for the station at S-79, which showed slight decrease.  Salinity at the Ft. Myers surface sensor was above the 1-day MFL criterion of 20 ppt.  The current surface salinity of 15 ppt at S-79 is 5 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 for a third consecutive week. In a few regions the recessions were actually a little too high but not a concern since water depths are in general, still too high (<1.0 ft) for wading bird foraging, especially in WCA-3A.  Stages throughout the WCA’s continue to decline and are close to Regulation in WCA-2A  and WCA-3A.  The WCA-2A marsh has been well above regulation for at least; the last three months.

 

Everglades National Park

 

Little rainfall & high ET caused water levels to decline across ENP wetlands last week.  Water level dropped by 2.9” over the 7 d period at Taylor Slough Bridge (not an unusual recession rate at this station), and by 1.9” in the southern part of Taylor Slough (at Craighead Pond, a more substantial decline for this area).  The weekly decline 0.4” in Shark River Sl. (station P33) was lower than that for other stations because of high rainfall in this area the week prior.

 

Salinity in Florida Bay either remained stable or increased.  Bay salinity typically peaks during this time of the year, when evaporation is very high & the rains have yet to kick in; concentrations herein described are near seasonal norms.  Salinity held in the mid-30s at Trout Creek and in the lower 30s at the mouths of Taylor River & L. Madeira Bay.  In the Taylor ponds, daily mean salinity reached over 30 psu at Pond 5 (USGS station) and Argyle Hendry (ENP station TR).  As of Sunday, 5/11, the 30d moving average concentration at TR (used for tracking the FL Bay MFL criterion) was at 24.6 psu (up from 22.4 psu last week).  At the Central Bay station in Whipray Basin salinity approached 40 psu by the end of last week.  Salinity in the upstream reaches of Shark River (Tarpon Bay platform) measured slightly above the seasonal norm (mid-teens) last week, reaching just over 20 psu as of Sunday, 5/11.

 

Recent synoptic mapping indicate that chlorophyll concentrations are approx. ˝ of what they were earlier this year in eastern areas of FL Bay. In the central Bay; chlorophyll remains fairly low (< 5 ug/L). The southern bloom region near Twin Key Basin was not mapped.

 

Wildlife

 

Last week a total of 1195 nests (795 egrets and 400 White Ibis nests) were reported. 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. This week a new large colony of some 4500 nests (mostly White ibis) was observed at the Lox West location of the Loxahatchee National Wildlife Refuge.

 

Water Supply

 

Last week was relatively dry, so most water levels decreased slightly across the SFWMD.  Water levels in the upper and lower Kissimmee Basin are now near or slightly below their historical average conditions for this time of year.  Water levels in the Lower West Coast are now near their historical averages, though some water levels are slightly below or slightly above those conditions 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 are now 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 – although they have been declining steadily over the past week.  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 Nińa climactic conditions.

 

CC:      George Horne