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 17, 2008

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Above average rains south today and tomorrow.  A developing mid to upper trough extends down into the eastern Gulf of Mexico.  This pattern in June is frequently associated with widespread seabreeze showers/storms over the peninsula.  In this case, showers/storms will focus south of the Lake where more favorable moisture and upper level winds exist.  Some northward expansion is likely under this pattern on Wednesday, so look for a higher coverage of storms tomorrow afternoon.  Some decrease is then likely on Thursday as the trough over the Gulf weakens.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 1.97 inches of rainfall to bring the 30 day total to 4.43 inches (82% of average), and the lower basin received 2.34 inches to bring the 30 day total to 4.18 inches (78% of average).  The spring recession of the regulation schedule has ended in the upper basin lakes.   Consequently, releases have ended from all lakes except for minimal releases from Lake Kissimmee for the Kissimmee River.  All upper Kissimmee Basin lakes are below regulation schedule.

 

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 336 days (S-65 re-opened on 07/18/07).  Flow is approximately 250 cfs at S65 and 250 cfs at S-65C.  River stage within the Kissimmee River Restoration Project area increased by approximately 0.5 ft in the last week.  However, much of the floodplain within this area is dry except for isolated pools.  These pools continue to attract foraging wading birds.  The water level in the area of the restoration project decreases by 0.41 feet from 34.08 feet near the upstream end (station PC62) to 33.67 feet at the downstream end (headwater stage at S-65C).

 

Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 2.2 mg/L to 7.4 mg/L with an average of 5.8 mg/L.  Although dissolved oxygen concentrations are beginning to decrease as temperatures rise, concentrations remain above levels of concern.


Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.27’ NGVD, which is 0.08’ lower than a week ago and 0.56’ lower than a month ago.  The current stage is 0.35’ higher than it was a year ago and 4.02’ below its historical average for this time of year.  Reported inflows include 135 cfs from the Kissimmee River and 48 cfs from the L8 at Canal Point.  No outflows are reported.

 

May water-quality monitoring results are now available.  Fourteen of the 25 monitoring stations had sufficient water for sampling.  Total P averaged 185 ppb lakewide (compared to 111 ppb in April) and 52 ppb at nearshore stations (compared to 33 ppb in April).  Total suspended solids (TSS) averaged 68 ppm lakewide (compared to 35 ppm in April) and 14 ppm at nearshore stations (compared to 6 ppm in April).

 

The monthly submerged-aquatic-vegetation (SAV) survey was completed last week.  Twenty six sites had sufficient water for sampling, and all sites had water clarity conducive to plant growth (secchi depth > 50% of total depth).  The macroalga Chara remains the dominant SAV species and was found at 15 of the 26 sites.  The vascular SAV species Vallisneria americana was present 8 of the 16 sites sampled near the northern and western shorelines but continues to be absent in the south (10 sites sampled).  Other observations indicate that Vallisneria beds continue to expand along the western shoreline, but recent declines in lake level have exposed some of these beds.

 

Approximately 2000 tires that had been illegally dumped on Kreamer Island have been removed as part of the low lake level enhancement project.  The current drought situation has made the island accessible for locating, identifying, and removing of such hazardous debris.

 

St. Lucie Estuary

 

There were no releases through S-80 from C-44 and S-49 from C-24 over the past week.  An average discharge of 13.65 cfs from S-48 of C-23 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)

18.05 (18.06)

20.77 (20.11)

 

HR1 (N. Fork)

21.05 (20.92)

23.42 (22.16)

 

Roosevelt Bridge

24.22 (23.72)

25.42 (24.43)

8.0 – 25.0

A1A Bridge

29.83 (29.82)

NA (30.31)

20.0 – 31.0

 

Compared with salinities of the previous week, average salinity increased slightly throughout the estuary.  The surface salinities at both Roosevelt and A1A Bridge are just within the upper limit of the preferred range.  The bottom salinity at Roosevelt Bridge has exceeded the preferred range.  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 24 ppt at the Roosevelt Bridge is 4 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 111 cfs occurred at S-79 and 230 cfs occurred at S-77.  No discharge occurred at S-78.  The concentration of chlorides at the Olga Plant was 228 ppm on June 16, down from 232 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)

17.84 (19.97)

20.06 (21.53)

Rt. 31 Bridge

18.25 (20.20)

22.68 (22.91)

I-75 Bridge

20.71 (21.80)

22.55 (23.03)

Ft. Myers Yacht Basin

24.67 (26.11)

25.67 (26.50)

Cape Coral Bridge

30.04 (31.73)

29.98 (32.16)

Shell Point

35.08 (35.70)

35.22 (36.46)

 

Average salinities dropped about 1-2 ppt throughout the estuary.  Average salinity at the Ft. Myers surface sensor was 24.67 ppt, still above the 1-day MFL criterion of 20 ppt.  The current surface salinity of 17.8 ppt at S-79 is 2.2 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 this week in water samples collected alongshore between Pinellas County and the Florida Keys or offshore of Sarasota and Monroe counties.  Discolored water is possible alongshore of Charlotte and Lee counties 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

 

Stages increased throughout the WCA’s in response to increasing rainfall amounts and extent.  Wet season precipitation exceeded evapotranspiration causing stages to increase from a low of 0.02 ft in WCA-2B to a high of plus 0.55 ft in WCA-3B.  Despite increasing stages, wading bird foraging depths continue to be fair in WCA-1, good in WCA-2A and fair in WCA-3A.  Stages are currently below regulation in WCA-1, slightly above regulation in WCA-2A and within the E1 zone of the WCA-3A Regulation Schedule

 

Everglades National Park

 

Rainfall platforms with sufficient data showed a wide range, from 0.2” (in Florida Bay) to 5.6” (in Tarpon Bay, downstream end of Shark River).  Trends for Everglades National Park (ENP) wetland water levels were again mixed in response to variable rainfall patterns.  Water level increased by just over 2.25” in Shark River Slough at P33, and by 7” at Taylor Slough Bridge.  The panhandle (station EVER6), on the other hand, saw water level drop slightly (0.2”).  Water level was down by 0.6” in the southern part of Taylor Slough at Craighead Pond, an area where stage remains well below normal for this time of year.

 

Salinity across Florida Bay remains high.  Concentrations were in the upper 30s (most platforms near 40 psu) across the northeast Bay.  In the Taylor ponds, salinity remained in the upper 30s for another week at both Pond 5 (USGS station) and Argyle Hendry (ENP station TR) platforms.  As of Sunday, 6/15, the 30 day moving average concentration at TR (used for tracking the Florida Bay MFL criterion) was at 34.8 psu (up from 33.5 psu last week).  Salinity remained in the upper-40s in the northcentral Bay areas of McCormick Creek and Terrapin Bay.  The central Bay station in Whipray Basin recorded salinity in the mid 40s for another week.  Salinity in the upstream reaches of Shark River (Tarpon Bay platform) declined last week (to 12 psu) due to high regional rainfall.

 

Wildlife

 

A limited June nest count indicated a total of 11175 nests (3400 egrets and 7775 White Ibis nests) in the LNWR, on June 1st. Casual observations indicate that these late breeding birds continue to forage in the LNWR, WCA-2A and in STA’s, and that birds will fledge over the next 2-5 weeks if water levels do not rise too much or too quickly.

 

Water Supply

 

Although there was some scattered rain last week, most water levels declined across most of the District.  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 rebound this week in wells completed in the shallow aquifers.  Water levels in the Lower East Coast are near or slightly below their 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, although they have been declining over the past few weeks.  Water levels in the southernmost portion of Miami-Dade County are now significantly below their average historic conditions.

 

The Water Supply Risk Indicators were not available at the time of this writing.

 

A review of the Minimum Flows and Levels (MFL) data for this month indicates that the Fort Myers Yacht Basin and the Rockland Marsh sites (in the northern area of Everglades National Park) are now exceeding the applicable measurement criteria for water level or concentration, duration and frequency.

 

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