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:                 June 24, 2008

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Scattered showers/storms focused southwest through northwest of the Lake this afternoon.  High pressure is finally building northward as evident by the easterly winds in the low levels of south Florida soundings.  Storms will form inland east and move westward late morning through this afternoon.  Then, our first interaction with a tropical wave occurs tomorrow.  Moisture will increase, especially south, and favorable upper level winds will help generate an above average rain day.  Drier air will follow the wave on Thursday with below average rainfall expected the end of the week and into the weekend.  The next ten days precipitation outlook is below average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 2.28 inches of rainfall to bring the 30 day total to 6.07 inches (96% of average), and the lower basin received 2.22 inches to bring the 30 day total to 5.50 inches (89% of average).  With the recent rainfall, water levels in most of the lakes are beginning to rise but all remain below regulation schedule. Lake Kissimmee remains at 49 feet.

 

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 343 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 remained above thresholds of concern.  Concentrations ranged from 3.6 mg/L to 7.3 mg/L and averaged of 5.3 mg/L.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.32’ NGVD, which is 0.05’ higher than a week ago and 0.43’ lower than a month ago.  The current stage is 0.40’ higher than it was a year ago and 4.06’ below its historical average for this time of year.


Total reported inflows are approximately 1600-1700 cfs and include 496 cfs from the Kissimmee River, 553 cfs through the S71, 133 cfs through the S72, 246 cfs from the L8 at Canal Point, and approximately 200-300 cfs through the S308.  No outflows are reported. 

 

Monthly phytoplankton monitoring was conducted yesterday.  Despite calm conditions, secchi depths were only 30-50% of total depth.  The cause of these rather low transparencies could not be determined.  The water column had a slight greenish hue, but otherwise there were no signs of bloom formation at any of the sampling locations.

 

Muck removal operations are underway in the littoral zone in the vicinity of Worm Cove and Horse Island.  Approximately 130 acres will be scraped within the next few weeks.  A similar project approximately 50 acres in size should begin in the Harney Pond area within the next few weeks and be completed by August.

 

St. Lucie Estuary

 

There were no releases through S-80 from C-44 over the past week.  An average discharge of 200 cfs through S-48 from C-23 and 190 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).

 

 

Weekly Average Salinity (ppt)

 

Sampling Site

Surface

Bottom

Envelope

Palm City Bridge (S. Fork)

17.42 (18.05)

19.76 (20.77)

 

HR1 (N. Fork)

17.66 (21.05)

22.02 (23.42)

 

Roosevelt Bridge

21.51 (24.22)

23.18 (25.42)

8.0 – 25.0

A1A Bridge

29.48 (29.83)

NA (NA)

20.0 – 31.0

 

Compared with salinities of the previous week, average salinity decreased throughout the estuary due to local runoff.  Salinities at HR1 and Roosevelt Bridge decreased about 2-3 ppt.  Salinity at Palm City Bridge decreased 1 ppt.  Salinity decreased only slightly at A1A Bridge.  Salinity conditions in the estuary are considered fair, based on the salinity preference of the oyster, Crassostrea virginica, at Roosevelt Bridge.  The current surface salinity of 21.5 ppt at the Roosevelt Bridge is 6.5 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 334 cfs occurred at S-79.  No flow was reported at S-77 except for 98 cfs discharge back to the Lake on June 22.  The concentration of chlorides at the Olga Plant was 178 ppm yesterday, down from 228 ppm in the beginning of this reporting period. Current weekly average salinity (in bold) may be compared to last week’s data (in parenthesis).

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

13.53 (17.84)

14.80 (20.06)

Rt. 31 Bridge

16.80 (18.25)

20.10 (22.68)

I-75 Bridge

17.96 (20.71)

20.76 (22.55)

Ft. Myers Yacht Basin

23.75 (24.67)

24.16 (25.67)

Cape Coral Bridge

28.81 (30.04)

29.21 (29.98)

Shell Point

34.37 (35.08)

34.42 (35.22)

 

Average salinities dropped throughout the estuary, ranging from about 5 ppt at S-79 to only about 1 ppt at Ft. Myers to Shell Point. Average salinity at the Ft. Myers surface sensor was 23.8 ppt, still above the 1-day MFL criterion of 20 ppt.  The current surface salinity of 13.5 ppt at S-79 is 6.5 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.  Salinity conditions in the upper estuary east of Ft. Myers are still poor due to high salinity.  Conditions in the lower estuary downstream of Cape Coral are becoming poor considering the combine salinity preference of oysters and seagrasses.

 

No Karenia brevis, the Florida red tide organism, was detected through June 20th, in water samples collected alongshore between Pinellas and Collier counties.  Discolored water is possible alongshore of Lee County due to the continued presence of high concentrations of the marine cyanobacterium Trichodesmium. Trichodesmium can collect at the water surface and appear brown, green, or white.  At high concentrations, a Trichodesmium bloom may be mistaken for an oil or sewage spill.

 

Water Conservation Areas

 

The heavy rainfall this week produced rapid reversals and elevated stages throughout the Greater Everglades.  Stages rose between 0.2 ft in WCA-3B to 0.82 ft in northeastern Shark River Slough.  Stage reversals produced poor conditions for wading bird foraging throughout the Everglades, and depths were also generally poor for foraging except in parts of WCA-2B and WCA-3B.  With the high rainfall this week, stages in WCA-1 and WCA-2A are above regulation, and are at regulation in WCA-3A.

 

Everglades National Park

 

Substantial rainfall totals were measured across the southern Everglades last week, including accumulations of 2.5-7.1” in Everglades National Park (ENP) and Florida Bay.  The basin-wide rainfall was 5.2” in the ENP basin and 4.7” in the C-111 basin, a welcome increase from weeks past.

 

In response to this much-needed rainfall, water levels rose across the ENP wetlands.  Water level increased by a substantial 3.7” in Shark River Slough at P33, 16” at Taylor Slough Bridge, 9.4” in the panhandle (station EVER6), and 8.2” in the southern part of Taylor Slough at Craighead Pond.  Stage still remains below average for this time of year at Taylor Slough Bridge and Craighead Pond, but this week’s increases improved deficits in Taylor Slough.  As of June 18th, moderate flows (< 200 cfs) occurred from S332D towards Taylor Slough.

 

Salinity across Florida Bay remains elevated, but declined following the heavy rainfall.  Concentrations dropped into the mid-30s across northeast Florida Bay last week.  Salinity in the Taylor ponds declined considerably from the mid-upper 30’s 2 weeks ago to the lower-mid 20’s last week   These declines will show up in the Taylor River (TR) 30-day moving average (used for tracking the FL Bay MFL criterion), but they presently remain at 34.5 psu (nearly unchanged from last week’s reading).  Salinity also dropped substantially in the north central Bay areas of McCormick Creek and Terrapin Bay, from the upper-40s in last week’s report, down to the mid-30’s this past week. The central Bay station in Whipray Basin recorded salinity in the mid-40’s for another week, despite receiving 5.6” of rainfall for the week.  Salinity in the upstream reaches of Shark River (Tarpon Bay platform) remained near 12 psu for another week, a bit above average for this time of year


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 during the persistent La Niña climactic conditions.

 

CC:   George Horne