MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       March 18, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Showers returning early Thursday through Saturday.  Breezy southeast winds will bring a few light sprinkles to the east coast today but otherwise dry conditions remain in place over the District with an old frontal boundary to our south.  Expect this front to lift back north ahead of the next system Wednesday and allow some widely scattered afternoon showers mainly east.  The next cold front will then move into central Florida Thursday morning and then move to near Lake Okeechobee Thursday evening before stalling across south Florida.  The stalled front will then wave north and south Friday and Saturday before moving completely south of the District Saturday night.  Expect scattered light to moderate rainfall near the frontal boundary each day Thursday through Saturday.  The next ten days precipitation outlook is below average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.25 inches of rainfall to bring the 30-day total to 3.62 inches (121% of average) and the lower basin received 0.22 inches to bring the 30-day total to 3.36 inches (128% of average).  Rainfall from two weeks ago had caused water levels to rise (stage reversals) in all of the lakes in the upper basin.  These reversals have ended and were approximately 0.1-0.2 ft.

 

The discharge from Lake Kissimmee (S-65) was increased to approximately 1500 cfs to the Kissimmee River to begin a gradual recession in lake water level.  Releases of 1200 cfs are being made from Lake Toho (S-61) and of 500 cfs from East Lake Toho to allow a more gradual water level recession during the snail kite nesting season.  Releases continue from Lakes Hart and Mary Jane and from Lakes Myrtle, Preston and Joel.  No other releases are being made in the upper basin.  In the upper basin, snail kites have increased the number of nests on East Lake Toho and Lake Toho.  About 80% of the snail kite nests in south Florida are on Lake Toho.

 

A whooping crane continues to nest on Lake Kissimmee.

 

Flow has been reestablished to the Kissimmee River for 237 days (S-65 re-opened on 07/18/07).  Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 3.7 mg/L to 8.7 mg/L with an average of 6.9 mg/L.

 

Land Stewardship will continue burning in Hickory Hammock and completed two upland burns at Oak Creek last week.

 

A recommendation was made last week to modify the water level recession in Lake Toho so that the water level in the lake would reach 53.5 feet at the same time as the approved regulation schedule and then be lowered according to the regulation schedule.  This recommendation was intended to address concerns raised by the U.S. Fish and Wildlife Service about increased loss of snail kite nests in Lake Toho, when water levels drop below 53.5 ft.  This adjustment should slow the recession and increase the amount of time that the lake would remain above 53.5 ft.

 

On Thursday March 13, 2007, U.S. Fish and Wildlife Service sent a request for a deviation to the U.S. Army Corps of Engineers to hold the water levels in Lake Toho 0.5 ft above the regulation schedule line until June 1.  This deviation was requested to increase the amount of time that water levels are above 53.5 ft.  When water levels fall below this threshold, there is concern that the there is an increase the number of snail kite nest failures.  This request is being considered by the Corps.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.23’ NGVD, which is 0.10’ higher than a week ago and 0.10’ higher than a month ago.  The current stage is 0.58’ lower than it was a year ago and 4.27’ below its historical average for this time of year.  Reported inflows cfs include the Kissimmee River (~1400 cfs), S71 (~150 cfs), S77 (~100 cfs), and the L8 at Canal Point (~650 cfs).  No outflows are reported.

 

February water-quality monitoring results are now available.  Fourteen of the 25 monitoring stations had sufficient water for sampling.  Total P averaged 152 ppb lakewide (compared to 240 ppb in January) and 77 ppb at nearshore stations (compared to 102 ppb in January).  Total suspended solids (TSS) averaged 54 ppm lakewide (compared to 109 ppm in January) and 26 ppm at nearshore stations (compared to 31 ppm in January).

 

Reconnaissance of the lake shoreline between Harney Pond and Clewiston last week revealed extensive but patchy beds of Vallisneria americana growing in about 30-45 cm of water.  Plants remain small (< 5 cm in height) but are exhibiting substantial lateral expansion by rhizomes.  A drop in lake levels below about 9’ NGVD will dry out many of these newly established beds.  The abundance of vascular SAV farther offshore could not be determined due to moderate turbidity.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  A discharge of 46.86 cfs occurred at S-97 on the C-23 Canal and there were no discharges 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)

9.02 (10.30)

10.88 (11.71)

 

HR1 (N. Fork)

12.53 (15.58)

15.42 (16.76)

 

Roosevelt Bridge

16.57 (18.42)

17.44 (18.62)

8.0 – 25.0

A1A Bridge

25.33 (26.30)

27.89 (28.11)

20.0 – 31.0

 

Average salinity decreased during the past week 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 16.57 ppt at the Roosevelt Bridge is 11.43 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 over the past week averaged 110.29, an increase from the previous week with 58.57 cfs.  The concentration of chlorides at the Olga Plant is 242 mg/l.  Average salinity decreased by 4 ppt on the surface at Franklin Locks with a gradual decrease at all sites moving down the estuary.  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)

12.69 (16.68)

13.31 (16.64)

Rt. 31 Bridge

14.27 (16.86)

16.32 (17.73)

I-75 Bridge

15.91 (NA)

18.65 (19.86)

Ft. Myers Yacht Basin

23.59 (23.11)

23.81 (23.15)

Cape Coral Bridge

28.20 (30.53)

30.52 (31.07)

Shell Point

34.73 (34.86)

35.67 (36.22)

 

Salinity at the Ft. Myers surface sensor remains above the 1-day MFL criterion of 20 ppt.  The current surface salinity of 12.69 ppt at S-79 is 7.31 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.  Conditions in the upper estuary east of Ft. Myers are poor due to high salinity.  Based on the salinity tolerances of oysters 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 Monroe counties.  Additional samples collected offshore of the Florida Keys also contained no K. brevis.

 

Water Conservation Areas

 

Water depths remain above one foot at many of the reported gages and are above the optimum depths for wading bird foraging.  However, there are good water depths and recession rates in NW WCA-3A and good water depths and fair recession rates in southern WCA-3B.  It is still early in the nesting season and it is hoped that these current hydrologic conditions we are experiencing for most of the WCAs will have a minimum impact. Stages in WCA-1 and WCA-2A remain above regulation, and WCA-3 stages are right at the bottom end of the E1 regulation schedule.  There have been some fires reported in WCA-3A south of I-75.

 

Everglades National Park

 

Rainfall across Everglades National Park (ENP) and Florida Bay last week was very light (0.06” spatial average across the region).  As a result, water levels across ENP wetlands continued to decline last week.  One exception is at P33 (in SRS) where there was a brief downpour of nearly 1.6” on 3/11.  Despite the rain event in SRS, stage was down by 1.2” at station P33 last week.  At Taylor Slough Bridge water level dropped by another 3.4” in the past 7 days (not an uncharacteristic decline for this area).  To the south, water level declined by 0.8” in Craighead Pond and by 1.3” in the ENP panhandle (station EVER6).

 

Data problems persist with some of the ENP marine platforms for salinity data.  Salinity concentrations remained generally stable or increased slightly last week at stations in Florida Bay for which data was available.  Salinity remained in the upper-20s to near 30 psu at Trout Creek., and held in the lower-20s at the mouth of Taylor River last week.  Salinity concentrations in the Taylor ponds increased at the end of last week, up to 15 psu in Pond 5.  In the north central Bay areas of McCormick Creek and Terrapin Bay salinity climbed throughout the week upwards of 30 psu.  Salinity in the central Bay, at Whipray Basin, has climbed rapidly in recent weeks, and is now approaching 40 psu (measuring 38.4 as of Sunday, 3/16).  As a whole these regional salinity concentrations are near seasonal norms.  The exception to this near-normal trend is in areas downstream of Shark River Slough where salinity measured just above 20 psu in Tarpon Bay as of Sunday, 3/16, a concentration that is above normal for this time of year.  This is not surprising given the low water levels and flows through SRS this water year.

 

Wildlife

 

We had a tragic plane crash this last week where three FAU graduate students were killed.  They were all part of a larger program to study bird foraging and nesting behaviors within the Everglades and Lake Okeechobee marshes.  The District has relied on this group to help us understand and to report bird populations during the dry season nesting period.  It is a great loss and one that shows how we as a scientific community are integrally linked.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and remain slightly below their historical average conditions for this time of year; although they increased somewhat this past week as a result of local rains.  Water levels in the Lower West Coast are a “mixed bag” of slightly higher and lower than historical averages, depending on the degree of confinement of the aquifers.  Water levels in the Lower East Coast are 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 above their historic averages as a result of local 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 or slightly below their average historic conditions.

 

There was no change in the Water Supply Risk indicators this week.  Five out of eleven risk measures are in the “high” risk category including the projected Lake Okeechobee Stage (SSM), the CPC Precipitation Outlook, and Lower East Coast Service Areas 1, 2 and 3.  The Palmer Index for LOK Tributary Conditions improved from “high” to “moderate” risk this week.

 

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.

 

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