MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       March 25 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Scattered showers returning this weekend.  High pressure behind a cold front will bring dry conditions today and Wednesday.  As winds switch back to the east and southeast, isolated to widely scattered showers will pop up mainly southeast Thursday and Friday.  Scattered afternoon showers and isolated thunderstorms will then develop mainly near the coasts 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 0.45 inches of rainfall to bring the total for March to 3.22 inches (130% of average) and the lower basin received 0.76 inches to bring the March total to 3.46 inches (156% of average).  While March rainfall for the upper and lower Kissimmee basins are above average, the totals since January 1 are only 102% of the long-term average for the upper basin and 108% for the lower basin.

 

The discharge from Lake Kissimmee (S-65) was increased to approximately 2000 cfs to continue a gradual water level recession and provide flow to the Kissimmee River.  Releases from Lake Toho (S-61) continue at 1200 cfs.  Releases from East Lake Toho were decreased to 200 cfs.  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 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 244 days (S-65 re-opened on 07/18/07).  The increased inflow from the upper basin is inundating 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 4.5 mg/L to 7.8 mg/L with an average of 6.2 mg/L.

 

The U.S. Army Corps of Engineers began discussions last week with an interagency team on the U.S. Fish and Wildlife Service’s request for a deviation to the regulation schedule for Lake Toho.  The request is to hold water levels 0.5 ft above the regulation schedule line until June 1.  Most of the snail kite nests this year have been reported on Lake Toho.  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 10.23’ NGVD, which is the same as a week ago and 0.10’ higher than a month ago.  The current stage is 0.41’ lower than it was a year ago and 4.20’ below its historical average for this time of year.  Reported inflows cfs include the Kissimmee River (~1850 cfs), S71 and S72 (~250 cfs), and the L8 at Canal Point (~434 cfs).  No outflows are reported.

 

St. Lucie Estuary

 

There were no releases through S-80, S-97 (on the C-23 Canal), or S-49 (on the C-24 canal) 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)

11.75 ( 9.02)

13.11 (10.88)

 

HR1 (N. Fork)

14.52 (12.53)

16.24 (15.42)

 

Roosevelt Bridge

18.06 (16.57)

19.06 (17.44)

8.0 – 25.0

A1A Bridge

27.51 (25.33)

29.35 (27.89)

20.0 – 31.0

 

Average salinity increased about 2 ppt 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 18.06 ppt at the Roosevelt Bridge is 9.94 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.  The concentration of chlorides at the Olga Plant is 240 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)

16.06 (12.69)

16.07 (13.31)

Rt. 31 Bridge

15.01 (14.27)

18.40 (16.32)

I-75 Bridge

15.70  (15.91)

18.70 (18.65)

Ft. Myers Yacht Basin

23.52 (23.59)

23.67 (23.81)

Cape Coral Bridge

29.03 (28.20)

30.08 (30.52)

Shell Point

34.73 (34.73)

35.57 (35.67)

 

Compared with last week, average salinity increased by about 3 ppt at Franklin Locks and 1-2 ppt at Bridge 31.  Average salinity in the rest of the estuary remained about the same as last week.  Salinity at the Ft. Myers surface sensor remains above the 1-day MFL criterion of 20 ppt.  The current surface salinity of 16.06 ppt at S-79 is 3.94 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 slightly above the upper limit of the optimal range for the oyster, Crassostrea virginica.

 

In summary, conditions in the upper estuary east of Ft. Myers are still poor due to high salinity.  Conditions downstream of Cape Coral are fair for oysters and good for seagrasses.

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.

 

Water Conservation Areas

 

Surplus rain caused reversals and water depths to increase almost everywhere but especially in WCA-2A and WCA-3B.  The increasing depths have made large areas inhospitable for wading bird foraging.  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 are above Regulation, WCA-2A marsh remains well above regulation (note: canal levels dropped sharply 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) wetland water levels displayed mixed trends last week in response to the patchy nature of the weekend rain event.  Water levels increased at the two slough stations: up by 1.3” at P33 (Shark River Slough) & by 10.7” at Taylor Slough Bridge (not a typo – this part of the system regularly experiences wide fluctuations in water levels from rain, inflows, etc., especially when the water level is below ground surface).  To the south of these areas, though, water level barely increased in the ENP panhandle (stations EVER6, only up by 0.1’”), and actually declined for the week at Craighead Pond (down by 0.6”).

 

Salinity concentrations are increasing slightly across the coastal zone and Florida Bay.  Salinity remained in the upper-20s to near 30 psu at Trout Creek.  Salinity concentrations in the Taylor ponds increased up to 20 psu in Pond 5 and 17 psu at Argyle Hendry (station TR).  The 30 day moving average concentration at TR has increased by 2.4 psu to 6.9 psu, and is normal for this time of year.  Salinity in the central Bay, at Whipray Basin, has climbed in recent weeks, holding just below 40 psu (data were only available through Thursday March 20th, so it has possibly declined a bit in response to Saturday’s rain event).  As a whole 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 where salinity measured just over 19 psu in Tarpon Bay, a salinity more typically found in May).

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin remain slightly below their historical average conditions for this time of year; although they decreased somewhat this past week.  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 their average historic conditions.

 

There was one change in the Water Supply Risk indicators this week.  LOK Multi-Seasonal Net Inflow Forecast improved from moderate to low risk.  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 and LOK Seasonal Net Inflow Forecast 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