MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       March 4, 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 through Friday.  A weakening prefrontal trough will push a line of generally decaying showers storms into the District late today.  Look for a focus west through north of the Lake during the late afternoon and evening.  The associated cold front will push south of the Lake and stall Wednesday where it will provide a focus for more showers storms tomorrow afternoon.  The front will begin to return northward in 48 hours leaving unsettled conditions with showers focusing north on Thursday.  The front will again push southward on Friday with scattered showers storms focusing west through north of the Lake before exiting southeast on Saturday morning.  Look for District rains to average near an inch through this 120 hour window.  The next ten days precipitation outlook is near average with moderate confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received approximately 0.36 inches of rainfall to raise the 30-day total to 1.42 inches (52% of average) and the lower basin received 0.02 inches to raise the 30-day total to 2.09 inches (89% of average).  Water levels in the upper basin lakes are at or below their regulation schedules.

 

Lake Kissimmee (S-65) continued discharging approximately 250 cfs to the Kissimmee River.  Releases of 900 cfs are being made from Lake Toho (S-61) and of 200 cfs from East Lake Toho to allow a more gradual water level recession during the snail kite nesting season.  No other releases are being made in the upper basin.  In the upper basin, snail kites continue to nest on East Lake Toho and Lake Toho.  A whooping crane continues to nest on Lake Kissimmee.

 

Flow has been reestablished to the Kissimmee River for 223 days (S-65 re-opened on 07/18/07).  Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 5.3 mg/L to 7.9 mg/L with an average of 6.9 mg/L.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.07’ NGVD, which is 0.06’ lower than a week ago and 0.03’ higher than a month ago.  The current stage is 1.15’ lower than it was a year ago and 4.51’ below its historical average for this time of year.  Reported inflows cfs include the Kissimmee River (~250 cfs), the S77 (~50 cfs), and the L8 at Canal Point (~600 cfs).  No outflows are reported.

 

The District’s vegetation management group reports that the exotic water grass Luziola subintegra has spread from its initial reported location at the mouth of Fisheating Bay and is now distributed broadly across the bay.  This species is considered to be invasive and herbicide applications are being performed to control its spread.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  No discharge occurred at S-97 on the C-23 Canal or 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)

13.11 (10.6)

14.36 (13.1)

 

HR1 (N. Fork)

16.85 (15.9)

18.51 (18.2)

 

Roosevelt Bridge

20.35 (21.3)

20.78 (21.7)

8.0 – 25.0

A1A Bridge

27.86 (27.1)

29.23 (28.5)

20.0 – 31.0

 

Average salinity changed very little 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 20.35 ppt at the Roosevelt Bridge is 7.65 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

 

Caloosahatchee Estuary

 

There were no releases through S-79 over the past week, down from previous week’s 55 cfs.  The 30-day average is 48 cfs.  Freshwater flow back into the Lake from C-43, through S-77, averaged 53 cfs during the last week. The concentration of chlorides at the Olga Plant were stable during the last week, with 198 mg/l reported yesterday.  Average salinity changed very little throughout 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)

14.46 (14.2)

15.26 (14.5)

Rt. 31 Bridge

14.36 (15.1)

16.81 (17.1 )

I-75 Bridge

NA (NA)

17.78 (18.6)

Ft. Myers Yacht Basin

21.97 (22.5)

22.37 (22.5)

Cape Coral Bridge

27.46 (27.1)

30.21 (30.4)

Shell Point

34.15 (34.2)

35.34 (35.6)

 

Salinity at the Ft. Myers surface sensor remains above the 1-day MFL maximum criterion of 20 ppt.  The current surface salinity of 14.46 ppt at S-79 is 5.54 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.  However, salinity for seagrass in the area downstream of Cape Coral sensor is good.

 

In summary, conditions in the upper estuary east of Ft. Myers are poor due to high salinity.  Based on the tolerances of oysters, salinity 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 Collier counties.

 

Biscayne Bay

 

Salinity Report for January 2008.  The mean monthly salinity nearshore Manatee Bay increased 18 percent from December (24.5 psu) to January (29.0 psu) (Figure 1), but was 32 percent below the maximum salinity of 42.5 psu recorded during February 2005.  Within the last twelve months, mean monthly salinity has increased steadily from a low in October (18.0 psu), but is still below the high set last May (34.7 psu).

 

                   Figure 1

 

Water Conservation Areas

 

Dry season recession rates have returned to a typical pattern throughout the Greater Everglades.  Recession rates are good throughout WCAs 1 and 2, ranging from -0.05”/week to -0.16”/week.  While recession rates in most of WCA-3A are still poor, this week’s values are much better than those from last week and are beginning to decline.  Water depths are still rather high for good wading bird foraging in most of the conservation areas.  Foraging conditions are good to fair locally only in WCA-2B, northern WCA-3A, and all of WCA-3B.  Water depths range from 0.15’ to 2.24’ at all reporting gauges.

 

Stages in WCA-1 are about at regulation, the WCA-2A marsh has declined slightly from last week but is still far above regulation, and WCA-3 stages are slightly under regulation.

 

Everglades National Park

 

Everglades National Park (ENP) stations have not transmitted data since 2/28 (with latest data through 2/27), so data are not current.

 

Rainfall was patchy again last week across ENP and Florida Bay.  The ENP basin spatially-averaged RAINDAR total for the week was .22”.  Estimated weekly totals near or exceeding 1” occurred in southeastern areas of the ENP and in Florida Bay.  The C-111 basin-wide RAINDAR total for this period was 0.62”.  The USGS gauge at W. Highway Creek. reported just under 0.5” of rain for the week.  Rain in the region was heaviest on Wednesday, 2/27 (with little recorded since then).

 

Data are insufficient to estimate weekly water level trends across ENP wetlands, with EDEN stage data extending only through Friday, 2/29.  The 5-day trends (using the EDEN estimates) indicate decreased water levels in SRS (station P33) by just under 1”, with increased levels in the panhandle (station EVER6) by approx 0.5”.  No EDEN data are available for Taylor Slough Bridge, and data for Craighead Pond looked suspicious.

 

Salinity concentrations remained generally stable or declined slightly in Florida Bay last week.  Salinity dropped into the low-20s at Trout Creek.  At the mouth of Taylor River salinity read near 20 psu for another week  Salinity concentrations in the Taylor ponds remained in the single digits last week (USGS station at Pond 5).  The 30 day moving average concentration at Argyle Hendry (station TR, used to track Florida Bay MFL criterion) is unavailable.  Salinity concentrations dropped below 20 psu in the north-central Bay area of McCormick Creek.  As a whole these salinity concentrations are near seasonal norms.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and remain slightly below their historical average conditions for this time of year.  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 near their historic averages as a result of local rainfall and continue to rebound as a result of recent 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 is no change 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), the Palmer Index for Tributary Conditions, the CPC Precipitation Outlook, and Lower East Coast Service Areas 1, 2 and 3.

 

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