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:                        January 20, 2009

 

SUBJECT:     Weekly Environmental Conditions for Systems Operations

 

Summary

 

Discharge from Lake Kissimmee is approximately 322 cfs and discharge at S65C is 371 cfs. The floodplain of the Kissimmee River is essentially dry except in the extreme southern end of Pool B/C.  Lake Okeechobee stage is 13.64 feet NGVD, which is 0.17 foot lower than a week ago, 0.49 foot lower than a month ago, 3.55 feet higher than it was a year ago, and 0.09 foot higher then the simulated average using the current regulations schedule.  Salinity conditions in the St. Lucie Estuary are considered to be good based on the salinity preference of the oyster, Crassostrea virginica.  In the Caloosahatchee Estuary, salinity conditions are fair in the upper estuary, good in San Carlos Bay and good in the lower estuary.  Water levels in all three Water Conservation Areas continue to decline slowly.  Salinity values remained steady across Florida Bay.  Groundwater levels are declining due to the lack of rainfall, but most of the water supply indicators remain in the low risk category.

 

On December 15, 2008, the United States Army Corps of Engineers (USACE) discontinued base flows to the Saint Lucie estuary and increased flows to the Caloosahatchee Estuary to 650 cfs.  Today the USACE initiate a seven day pulse release to the Caloosahatchee Estuary that will average 650 cfs over the seven days.

Background

 

Freezing temperatures likely over the Kissimmee Valley down around Lake Okeechobee Wednesday and Thursday morning.  The coldest air since last January, and possibly since January 2003, will pour down the peninsula Tuesday through Tuesday tonight behind this morning’s cold frontal passage.  Thursday morning might be the worst of the two mornings as high pressure centers itself over the peninsula to allow calm winds and clear skies to maximize radiational cooling.  These events sometimes cause freezing temperatures for several hours at ground level over interior southern Florida.  Temperatures begin to moderate nicely Thursday afternoon through the weekend as high pressure moves east of the peninsula.  Not much hope for appreciable rainfall through this forecast period…next chance appears about 9 days away.  The next ten days precipitation outlook is below average with moderate 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 0.45 inches (19% of average) and the lower Kissimmee Basin received 0.23 inches of rain to bring the 30 day total to 0.41inches (23% of average).

 

Stage in Lakes Kissimmee, Hatchineha and Cypress is 1.8 feet below regulation schedule and stage in Lakes Tohopekaliga and East Tohopekaliga is 0.6 foot below regulation schedule.

 

The final treatment of hydrilla with Aquathol on Lake Toho will occur on Tuesday, January 27, 2009.  The originally planned 600 acre treatment plot has been reduced to 220 acres because water samples taken from this area after the December treatments showed herbicide residues at near-lethal levels in portions of that treatment area.


Surveys last week confirmed that some of this hydrilla is likely to die soon and that additional treatments are not warranted in all areas of the plot.  The updated treatment area is immediately south of Brown’s Point and does not include the deeper portions of the littoral zone.

 

Snail kite courtship and nesting behaviors are beginning to be observed around Lake Toho.

 

Discharge from Lake Kissimmee is approximately 332 cfs and discharge at S65C is 371 cfs.  The floodplain of the Kissimmee River is essentially dry except in the southern end of Pool B/C and adjacent to the active construction area.

 

Some shoaling has been observed within the river channel in the northern portion of the restored area.  Care should be taken when navigating through this area.

 

The dry season drawdown of the Pool B/C area is on track to reach a low stage target of 33 feet on or around May 15, 2009.

 

Wading bird activity observed during aerial surveys last Tuesday was average except near the active construction area.  One large flock of white ibis and some smaller mixed species flocks were observed on the west side of the construction area within flooded wet prairie.

 

Dissolved oxygen (DO) concentrations in the Kissimmee River ranged from 6.1 mg/L to 9.4 mg/L with a daily average of 7.9 mg/L.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 13.64 feet NGVD, which is 0.17 foot lower than a week ago, 0.49 foot lower than a month ago, and 3.55 feet higher than it was a year ago.  The current stage is 1.06 foot below the historical average for this date and 0.09 foot above the simulated average using the current regulation schedule (LORS2008).  Total reported inflows are 319 cfs and are limited to flows through S65E (311 cfs) and Fisheating Creek (8 cfs).  Total reported outflows are 1872 cfs and include environmental releases to the Caloosahatchee River (347 cfs), water-supply releases through the S351, S352, and S354 (1249 cfs) and to the L8 at Canal Point (135 cfs), and flow (140 cfs) through the S308.

 

December water-quality monitoring results are now available.  All 25 monitoring stations had sufficient water for sampling.  Total phosphorous averaged 152 ppb lakewide (compared to 225 ppb in November) and 139 ppb at nearshore stations (compared to 177 ppb in November).  Total suspended solids (TSS) averaged 21 ppm lakewide (compared to 67 ppm in November) and 16 ppm at nearshore stations (compared to 27 ppm in November.

 

Last week, transect sites along the western shoreline were sampled for submerged-aquatic-vegetation (SAV) to complete the monthly survey.  A total of 37 sites were sampled this month (five in the south, 25 in the north, seven in the west) and plants were found at 23 of those sites (zero in the south, 20 in the north, three in the west).  Last month 24 sites were visited and only eight had plants.  The increase in the number of sites with plants this month was due in part to being able to access more of the innermost sites in the north where plants are starting to colonize in areas that were dry before Tropical Storm Fay.  The innermost sites in the south and west are still too terrestrial to sample.

 

Monthly phytoplankton monitoring was performed at eight of the nine sites last Wednesday (January 14th) and no blooms were observed.  Mean secchi depth was 0.46 m (compared to 0.44 m in December) with greatest depths near the mouth of the Kissimmee River (>0.8 m).


Saint Lucie Estuary

 

Over the past week discharge averaged 0 cfs at S-80.  Discharge from the Lake at S-308 averaged 51 cfs.  Provisional data indicated that no discharge occurred at S-97 on C-23, or at S-49 on C-24.  The current weekly average salinities (in bold) at the four monitoring sites in the Saint 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)

12.2 (11.9)

14.0 (13.9)

 

HR1 (N. Fork)

NR (14.7)

NR (18.1)

 

Roosevelt Bridge

21.7 (19.7)

22.1 (20.4)

8.0 – 25.0

A1A Bridge

29.6 (27.2)

30.6 (28.6)

20.0 – 31.0

 

Salinity increased throughout the estuary during the past week.  Salinity at Roosevelt Bridge and A1A Bridge are within the preferred range.  Salinity conditions in the estuary are considered to be good based on the salinity preference of the oyster, Crassostrea virginica, and location in the estuary.

 

Caloosahatchee Estuary

 

During the last week, discharge averaged 652 cfs at S-79, 474 cfs at S-78, and 695 cfs at S-77.  The concentration of chlorides at the Olga Plant was 69 ppm yesterday.  The current weekly average salinities (in bold) at the six monitoring sites in the Caloosahatchee Estuary are given below in parts per thousand (ppt), along with the previous week’s (in parenthesis).

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

2.5 (3.4)

2.5 (3.6)

Rt. 31 Bridge

3.1 (4.0)

3.1 (4.1)

I-75 Bridge

3.6 (4.5)

4.9 (6.4)

Ft. Myers Yacht Basin

8.6 (11.5)

10.4 (12.8)

Cape Coral Bridge

18.6 (19.7)

19.1 (20.5)

Shell Point

26.6 (29.5)

28.8 (31.2)

 

Salinity declined over the past week.  Conditions in the upper estuary east of Fort Myers are fair (30 day average at Fort Myers equals 10.8 ppt).  Salinities at the Cape Coral Bridge are within the preferred range for the oyster, Crassostrea virginica, and well within the range tolerated by seagrass, Halodule wrightii.  Therefore, conditions in the lower estuary are good.  Salinity at Shell Point indicates that conditions are good in San Carlos Bay.

 

Fish and Wildlife Research Institute (FWRI) reports that water samples collected alongshore between Pinellas and Monroe counties contained no K. brevis.  Monitoring data collected by the River, Estuary and Coastal Observing Network (RECON) of Sanibel-Captiva Conservation Foundation (SCCF) indicated that over the last week Chlorophyll concentrations ranged between 2.5 and 8.1µg/L at Fort Myers and 2.0 to 49.0 µg/L at Shell Point.  The DO concentration at the two locations ranged from 5.5 to 9.7 mg/L.

 


Water Conservation Areas

 

Stages in all basins continue to decline at rates considered good for wading bird feeding and support of chicks.  Southern WCA-3A depths are still above 2.5 inches (175 days), still stressing tree islands, but water levels are declining.  Average weekly basin stage declines were:

 

Stage Change:            WCA-1:           - 0.07 foot        WCA-3A:         - 0.08 foot

WCA-2A:         - 0.09 foot        WCA-3B:         - 0.06 foot

WCA-2B:         - 0.09 foot        NESRS:          - 0.10 foot

 

Depths at gauges range from 0.40 foot in WCA-2A to 3.52 feet in WCA-2B, but most gauges report depths of one foot to a bit over two feet.  Local changes in water depths can be seen in the depth contours maps.  Areas of dryout are expanding with declining water levels in the northern areas of the water conservation areas, in Everglades National Park (ENP), and in Big Cypress Preserve.  The deep water north and west of the L-67 canals is declining as well.  Compartmentalization has led to annual drying that proceeds from the north to the south.  In the original system, peat rarely dried out.  Peat must remain hydrated to accumulate and to avoid loss through oxidation.

 

Continuing recent trends, WCAs 1 and 3 remain below the Regulation Schedule, while WCA-2 is above regulation.

 

Everglades National Park

 

Only trace precipitation fell across ENP and Florida Bay last week.  Stations for which we receive data from ENP measured from 0 foot–0.04 foot of rainfall over the week, and the basin-wide spatially-averaged weekly rainfall totals were 0.020 foot and 0.007 foot for the ENP and C-111 basins, respectively.

 

Stages continued to decline in ENP last week.  Water levels in Shark River Slough (P33) and at the Taylor Slough Bridge dropped by 1.4 inches and 4.7 inches, respectively.  To the south, water levels in the ENP panhandle (EVER6) and Craighead Pond dropped by 1.6 inches  and 0.7 inches, respectively.

 

Salinity was stable or declined in Florida Bay (Bay) last week.  In the eastern Bay, salinity was steady in the low to mid-20s near shore (Long Sound and Little Madeira Bay platform) and in the low 30s further into the Bay (Duck Key).  The 30 day moving average salinity at the Taylor River platform (used for tracking the Florida Bay Mean Flows and Levels) dropped slightly from 1.5 psu to 1.4 psu.  In the north central Bay, salinity dropped from the mid-20s to about 20 psu in Terrapin Bay and from the mid-20s to the upper teens in McCormick Creek.  At the central Bay platform in Whipray Basin, salinity was steady in the mid– to upper 30s.  Data transmission problems at station TE last week preclude reporting on salinity trends in Shark River Slough.

 

Water Supply

 

Water levels across the District continued to decline over the past week.  Many Floridan aquifer wells in the Kissimmee Basin have now slipped to the lowest 10% of their water levels, according to United States Geological Survey records.  Surficial aquifer levels in the Upper East Coast area are in seasonal decline with near median levels.  Water levels in the coastal portion of the Lower East Coast, particularly in southern Broward and northern Miami-Dade counties, are low for this time of the dry season.  A Biscayne aquifer well in the Davie area exceeded record low levels this past week.  Groundwater wells in Miami-Dade County are at or above their median values for this time of year and are declining. 

In the Lower West Coast area, groundwater wells are showing seasonal declines in water levels in the Surficial, Lower Tamiami and Sandstone aquifers.  Mid-Hawthorn aquifer wells remain mostly above average water levels for this time of year.

 

Water supply risk indicators are in the “low” risk category including the projected LOK Stage, the Water Conservation Areas 1 and 3A, and LEC Service Areas 1, 2, and 3 (no restrictions).

 

The CPC Precipitation Outlook, the LOK Seasonal Net Inflow Forecast, the LOK Multi-Seasonal Net Inflow Forecast, the Palmer Index for LOK Tributary Conditions, and Water Conservation Area 2A continue in the “medium” risk category.

 

LORS2008 (Lake Okeechobee Regulation Schedule)

 

Stages in Lake Okeechobee are now within the base flow sub-band.  Tributary inflows are currently in the dry category.  The seasonal outlook for net inflow into the lake is for dry conditions.  The LORSS recommended discharges are up to 450 cfs at S-79 and up to 200 cfs at S-80, and no discharges to the water conservation areas.

 

On December 15, 2008, USACE discontinued base flows to the St. Lucie Estuary and increased flows to the Caloosahatchee Estuary to 650 cfs.  Today the USACE initiate a seven day pulse release to the Caloosahatchee Estuary that will average 650 cfs over the seven day period.  The District recommends that the USACE initiate another seven day 650 pulse release to the Caloosahatchee Estuary when the current one is completed.