MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       April 1, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Some showers/storms each day with a focus west until Thursday before rains increase Friday/Saturday.  Look for mini wet season conditions through the weekend.  Dominant southeast winds will feed decent moisture into a marginally unstable atmosphere this week.  Seabreeze showers and a few storms will result with a focus west of the Lake.  Upper level winds should generate a higher coverage of activity today before coverage decreases some tomorrow and again Thursday.  Coverage of showers/storms should increase again Friday/Saturday ahead of a weakening cold front.  The next ten days precipitation outlook is average with moderate confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0 inches of rainfall to bring the 30 day total to 3.22 inches (99% of average), and the lower basin received 0.02 inches to bring the 30 day total to 3.48 inches (121% of average).

 

The discharge from Lake Kissimmee (S-65) continues at approximately 2000 cfs to continue a gradual water level recession and provide flow to the Kissimmee River.  Releases from Lake Toho (S-61) were decreased to 500 cfs.  Releases from East Lake Toho were decreased to 180 cfs.  Releases continue from Lakes Myrtle, Preston and Joel.  No other releases are being made in the upper basin.

 

In the upper basin, snail kites continue to nest on East Lake Toho, Lake Toho, and Lake Kissimmee.  A whooping crane continues to nest on Lake Kissimmee.  Flow has been reestablished to the Kissimmee River for 251 days (S-65 re-opened on 07/18/07).  The increased inflow from the upper basin continues to inundate a portion of the floodplain in the Phase I area of the Kissimmee River Restoration Project.

 

Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 2.1 mg/L to 6.6 mg/L with an average of 5.1 mg/L.

 

Last week the interagency team continued discussions of the U.S. Fish and Wildlife Service’s request for a deviation to the regulation schedule to hold water levels in Lake Toho 0.5 ft above the schedule line until June 1.  The deviation request is intended to improve snail kite nesting on Lake Toho by reducing the amount of time that water levels are below 53.5 ft.


Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.29’ NGVD, which is 0.06’ higher than a week ago and 0.23’ higher than a month ago.  The current stage is 0.13’ lower than it was a year ago and 4.10’ below its historical average for this time of year.  Reported inflows cfs include the Kissimmee River (1676 cfs), S77 (77 cfs), and the L8 at Canal Point (~605 cfs).  No outflows are reported.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  A discharge of 3.10 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)

11.77 ( 11.75)

12.99 (13.11)

 

HR1 (N. Fork)

NR (14.52)

NR(16.24)

 

Roosevelt Bridge

17.87 (18.06)

18.55 (19.06)

8.0 – 25.0

A1A Bridge

26.93 (27.51)

29.10 (29.35)

20.0 – 31.0

 

Average salinity decreased slightly 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 17.87 ppt at the Roosevelt Bridge is 10.13 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

 

Caloosahatchee Estuary

 

No discharge occurred at S-79 last week.  Discharge from S-77 into Lake Okeechobee averaged 69.29 cfs last week.  The concentration of chlorides at the Olga Plant is 202 mg/l.  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)

15.05 (16.06

16.12 (16.07)

Rt. 31 Bridge

14.19 (15.01)

18.87 (18.4)

I-75 Bridge

14.71  (15.70)

19.52 (18.70)

Ft. Myers Yacht Basin

21.67 (23.52)

23.94 (23.67)

Cape Coral Bridge

27.65 (29.03)

29.00 (30.08)

Shell Point

33.97 (34.73)

34.93 (35.57)

 

Compared with last week, average surface salinities decreased slightly throughout the estuary and bottom salinities increased slightly in the upper estuary and decreased slightly in the lower estuary.  Salinity at the Ft. Myers surface sensor remains above the 1-day MFL criterion of 20 ppt.  The current surface salinity of 15.05 ppt at S-79 is 4.95 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.

 

Biscayne Bay

 

Salinity Report for February 2008

 

Salinity nearshore Manatee Bay was not available in February 2008.  Mean monthly salinity nearshore Barnes Sound decreased 2 percent from January (31.1 psu) to February (30.4 psu) (Figure 1), and was 29 percent below the maximum salinity of 43.1 psu recorded during February 2005.  Within the last twelve months, mean monthly salinity increased from a low in October (19.8 psu), through January, but has leveled off.  The highest monthly mean within the last twelve months was set last March (35.0 psu).

 

Figure 1. Mean monthly salinity at recorder MDTS nearshore Barnes Sound.

 

Water Conservation Areas

 

Recession rates were either too slight or non-existent in WCA-2B, 3A, and 3B as a result of the rains of two weeks ago and from S-10 and S-11 openings.  Only WCA-1 and 2A had recession rates in support of foraging.  Unfortunately the depths throughout the Greater Everglades do not yet support foraging.  Depths greater than one foot are inhospitable for wading bird foraging. However, it is still early in the nesting season for ibis and it is hoped that these poor hydrologic conditions will have a minimum impact on this species.  Stages in WCA-1 have declined and are at Regulation, WCA-2A marsh remains well above regulation (note: canal levels continue to drop due the opening of the S-11’s), and WCA-3A stages are within zone E1 of the regulation schedule, for protection of the Cape Sable Seaside Sparrow.

 

Everglades National Park

 

Everglades National Park (ENP) and Florida Bay experienced patchy rainfall last week, with many areas receiving no rain. Despite rain in SRS, the ENP wetland water levels were down by approx. 1” for the week in both northern areas (SRS at P33) and southern areas (Craighead Pond).   After last week’s dramatic water level increase at Taylor Slough Bridge (up by nearly 11” from the previous week’s total), last week brought a 2.4” recession to this part of the system (an area that regularly experiences wide fluctuations in water levels from rain, inflows, etc., especially when the water level is below ground surface).

 

Salinity concentrations remained fairly stable or increased.  By the end of the week salinity had crept just above 30 psu at Trout Creek and into the mid-20s at the mouth of Taylor River.

As of Sunday, March 30th, the 30 day moving average concentration at Taylor River (used for tracking the Florida Bay MFL criterion) was at 9.5 psu (up from 6.9 psu last week), and the highest concentration seen yet this dry season.  Salinity in Whipray remained in the upper-30s to near 40 psu for much of the week.  These regional salinity concentrations are near seasonal norms.  The exception to this near-normal trend is out west, in areas downstream of Shark River Slough: though recent rainfall allowed salinity to drop a bit in Tarpon Bay, the daily mean measurement of 17 psu, is still well above normal and closer to concentrations experienced at the height of the dry season (in May) in this area.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and remain slightly below their historical average conditions for this time of year, they decreased somewhat this past week as a result of minimal 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 above their average historic conditions.

 

There was modest improvement in the Water Supply Risk indicators this week.  Six out of eleven risk measures are in the “high” risk category including the projected Lake Okeechobee Stage (SSM), Palmer Index for Tributary Conditions, the CPC Precipitation Outlook, and Lower East Coast Service Areas 1, 2 and 3.

 

The LOK Seasonal Net Inflow Forecast is now at “medium” risk and the LOK Multi-Seasonal Net Inflow Forecasts is now at “low” 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