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:            October 7, 2008

 

SUBJECT:     Weekly Environmental Conditions for Systems Operations

 

Summary

 

Floodplain depths in the restored area of the Kissimmee River continue to decrease and currently range from 0.5 to 1.5 feet in general. Recent observations revealed increased numbers of wading birds, waterfowl, migrant shorebirds and migrant songbirds foraging in and around the floodplain.

 

On September 30th, the United States Army Corps of Engineers (USACE) initiated a third, 12-day pulse release, with an overall average release of 2,200 cfs to the Caloosahatchee River and 1,000 cfs to the St, Lucie River.  Stages in Lake Okeechobee (Lake) are now within the low sub-band.  Inflows from the tributary basins have continued to taper off and are currently in the normal category for the tributary hydrologic conditions.  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 maximum practical discharges to the south if desired or with minimal impact.

 

Conditions in the St. Lucie estuary are considered to be poor based on the salinity preference of oysters.  Conditions in the upper Caloosahatchee estuary are considered good and conditions in the lower Caloosahatchee estuary are considered poor.

 

Average stage increases in each of the WCAs ranged from barely detectable (0.01 foot) in WCA-2B and Northeast Shark River Slough to over 0.5 foot in WCA-1.  Stages in WCA-3A and WCA-3B rose slightly.  Salinity concentrations declined across most of Florida Bay in response to both rainfall and heavy creek flows from the Everglades.

 

Background

 

Showers and storms focus north again.  Not much change is evident from Tuesday, except stronger low level easterly flow.  Therefore, look for showers and storms to focus east through north of the Lake with secondary development along the west coast late afternoon.  Look for a minor decrease in coverage tomorrow before a deep layered trough increases activity on Thursday.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received approximately 0.59 inches of rainfall to bring the thirty day total to 2.88 inches (52% of average).  The lower basin received approximately 0.94 inches to bring the thirty day total to 2.46 inches (45% of average).

 

Water levels in the upper basin lakes continue to closely follow their regulation schedules except for Lakes Kissimmee, Hatchineha and Cypress, which are almost 0.5 feet below regulation schedule.  Releases from the upper chain of lakes have ceased except for minor releases (<100 cfs) from Lakes Myrtle, Gentry and Alligator.

Discharge from Lake Kissimmee remained at approximately 300 cfs and discharge at S65C decreased from 700 cfs to 350 cfs.  Floodplain depths in the restored area continue to decrease and currently range from 0.5 to 1.5 feet in general.

 

Recent observations revealed increased numbers of wading birds, waterfowl, migrant shorebirds and migrant songbirds foraging in and around the floodplain in the restoration area.  The post-Fay drawdown is coinciding with peak migration for many species. Several flocks of migrant blue-winged teal (50-100+ per flock) were observed.  Black-bellied whistling ducks and mottled ducks also were seen.  Well over 200 wood storks were mixed with great egrets, white ibis, snowy egrets, tricolored herons and little blue herons.  At least one roseate spoonbill and several juvenile wood storks were observed as well.  Migrant shorebirds (mostly greater and lesser yellowlegs, least sandpipers, and spotted sandpipers) were on the floodplain as well as on newly formed or enhanced sandbars formed from Tropical Storm Fay’s high flows.  Migrant songbirds (mostly palm warblers, American redstarts, blue-grey gnatcatchers, and other warblers) were abundant in mixed-species flocks in shrubby areas and along the oak hammocks foraging on caterpillars.  From 9/30/08 to 10/7/08 dissolved oxygen concentrations in the Kissimmee River ranged from 1.2 mg/L to 4.1 mg/L and averaged 2.4 mg/L.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee (Lake) stage is 14.96 feet NGVD, which is 0.03 foot higher than a week ago, 0.11 foot lower than a month ago, and 4.87 feet higher than it was a year ago.  The current stage is 0.03 foot below the historical average for this date, and 1.09 feet above the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 2120 cfs, with the greatest contributions from S71 and S72 (1019 cfs), S191 (304 cfs), and the L8 at Canal Point (401 cfs).  Pulse releases to the estuaries continue at 1636 cfs through the S308 and 1054 cfs through the S77.

 

Generally light algal bloom activity continues to occur around the Lake.  Locations experiencing some surface-bloom activity include the shoreline from S191 to Taylor Creek and from Indian Prairie to the mouth of Fisheating Bay.  The extensive bloom reported two weeks ago across the northern part of the lake has dissipated.

 

Vegetation management crews have been active on the lake in recent weeks.  The large monoculture of the invasive exotic plant Luziola previously reported at the mouth of Fisheating Creek has been successfully treated with no evidence of regrowth.  Another invasive grass, West Indian Marsh Grass, has greatly increased in coverage since Tropical Storm Fay and is being treated.  Large growths of water hyacinth and water lettuce have also developed and are being treated.

 

Spikerush stands that established this past summer along the lake shoreline continue to persist despite continued high lake stage.  Stands along the southern shoreline still appear healthy, but those along the northwestern shoreline appear stressed, likely due to a combination of deep water, turbidity, and wave action.

 

St. Lucie Estuary

 

During the last week, an average discharge of 926 cfs occurred at S-80 from C-44 and 706 cfs at S308, 73 cfs discharge at S-97 from C-23, and 244 cfs discharge from S-49 from C-24 (discharge values from S-97 and S49 are provisional).  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 (South Fork)

1.07 (1.14)

1.86 (2.08)

 

HR1 (North Fork)

5.65 (4.73)

10.10 (9.57)

 

Roosevelt Bridge

7.14 (7.02)

9.10 (10.30)

8.0 – 25.0

A1A Bridge

15.16 (16.49)

21.99 (NR)

20.0 – 31.0

 

Compared with the previous week, average salinity remained about the same throughout the estuary.  Salinities are close to the lower limit of the preferred range at Roosevelt Bridge, and are within the preferred range at A1A Bridge.  Salinity conditions in the estuary are still considered to be poor based on the salinity preference of the oyster, Crassostrea virginica, and location in the estuary.

 

Caloosahatchee Estuary

 

During the last week, an average discharge of 3467 cfs occurred at S-79, 1152 cfs at S-78, and 267 cfs at S-77.  The concentration of chlorides at the Olga Plant was 59 ppm yesterday, up from 53 ppm at the beginning of this reporting period.  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)

0.23 (0.22)

0.24 (0.22)

Rt. 31 Bridge

0.23 (0.22)

0.24 (0.22)

I-75 Bridge

0.25 (0.25)

0.26 (0.26)

Ft. Myers Yacht Basin

0.25 (0.24)

0.25 (0.24)

Cape Coral Bridge

1.00 (1.76)

1.93 (2.57)

Shell Point

12.95 (13.30)

16.92 (17.42)

 

In the estuary, freshwater conditions extend from S-79 downstream to Cape Coral Bridge.  Salinity conditions in the upper estuary east of Ft. Myers are good (30 day average at Fort Myers equals 0.31 ppt).

 

Compared with the previous week, average salinity remained about the same throughout the estuary.  Salinities at Cape Coral Bridge and Shell Point are below the preferred ranges for both oyster, Crassostrea virginica, and seagrass, Halodule wrightii.  Therefore, conditions in the lower estuary between Cape Coral and Shell Point are considered poor.

 

Fish and Wildlife Research Institute reports that very low concentrations of Karenia brevis, the Florida red tide organism, were detected this week in water samples collected at Tarpon Beach and Lighthouse Beach on Sanibel Island (Lee County).  No impacts have been reported. In Sarasota County, background concentrations of K. brevis were detected near New Pass.  All other water samples collected alongshore between Pinellas and Collier counties contained no K. brevis.  A research cruise currently being conducted has found no K. brevis offshore between Manatee and Lee counties.  Monitoring data collected by the River, Estuary and Coastal Observing Network of Sanibel-Captiva Conservation Foundation indicated that Chlorophyll concentrations over the last week were about 4.5-5.5 ug/L at Fort Myers and 1.5 to 4 ug/L at Shell Point.  The dissolved oxygen concentration at the two locations ranged from about 4 to 6 mg/L.


Water Conservation Areas

 

Water levels rose again with the week’s rainfall.  Average stage changes in each of the Everglades areas ranged from barely detectable (0.01 foot) in WCA-2B and Northeast Shark River Slough to over 0.5 foot in WCA-1.  Stages in WCA-3A and WCA-3B rose slightly.  The average stage changes are listed below:

 

Change:          WCA-1:           0.51 ft             WCA-3A:         0.08 ft

WCA-2A:         0.09 ft             WCA-3B:         0.15 ft

WCA-2B:         0.01 ft             NESRS:          0.01 ft

 

Stages in WCA-1 have risen rapidly this week to just below the regulation depths.  WCA-2A stages rose slightly, and are still above their regulation.  This conservation area has now been above regulation for more than one full year.  WCA-3A stage rose slightly again this week (0.08 foot) and has been above regulation since mid-July.

 

Water depths at two gauges in the Greater Everglades range now exceed 4:  4.12 feet in the southern portion of WCA-2B and 4.03 feet in southern WCA-3A.  The lowest depth recorded at any of the gauges we use is 1.82 feet in central WCA-1.  Large areas of WCA’s 2A and 3B exceed 2.5 feet, a generalized threshold for tree island inundation.  Continuous inundation beyond 120 days potentially threatens the health of trees on the tree islands, so Inundation Days are now being tracked.  The southern region of WCA-3A is now 70 days above the tree island threshold, the ponded region of WCA-2B is now 84 days above this threshold, and northern and central areas of WCA-2B and -3A are 35-56 days into this 120 day period.  Efforts to lower stages in central WCA-2A have kept depths below this threshold for the last two weeks in spite of rainfall inputs.

 

Everglades National Park

 

Rainfall totals similar to those in the WCA’s fell across Everglades National Park (ENP) and Florida Bay last week.  Stations for which we receive data from ENP reported 1.7 – 3.9 inches for the 7 day period.  The basin-wide spatially-averaged weekly RAINDAR totals were 1.57 inches and 2.29 inches in the ENP and C-111 basins, respectively.

 

This rainfall increased stages in ENP wetland areas.  Water levels rose 2.25 – 2.75 inches for the week at several gauges regularly described in this report (Shark River Slough at P33, ENP panhandle at EVER6, and Craighead Pond).  Taylor Slough Bridge stages increased by nearly 6 inches, and ENP wetlands stages are now well above their seasonal averages.

 

Salinity concentrations declined across most of Florida Bay in response to both rainfall and heavy creek flows from the Everglades. By the weekend, salinity readings from the creeks feeding eastern Florida Bay had rapidly fallen below 10 psu, a particularly notable event following the flow reversals of recent drier weeks (including last week’s high tides).  The results of the earlier flow reversal in Taylor River, though, are still evident in the 30-day Florida Bay MFL salinity criterion of 8.9 psu on Sunday, virtually unchanged from last week’s reading (8.8 psu).  Salinity declined in the north central Bay into the low- to mid-20s in Terrapin Bay and McCormick Creek, the same concentrations recorded several weeks ago.  At the central Bay platform at Whipray Basin, salinity continued a slow downward trend, falling below 35 psu by Sunday.  Salinity remained near normal seasonal concentrations in upstream reaches of Shark River (at Tarpon Bay platform, salinity is nearly fresh, below 1 psu).


Water Supply

 

Water levels in the upper and lower Kissimmee Basin are now near or slightly below their average conditions for their respective periods of record, reflecting generally dry conditions north of Lake Okeechobee this week.  Groundwater levels in the western portion of the upper KB are generally lower than those in the eastern portion.  Water levels in the Lower West Coast are mostly above their historical averages although wells in the upper Caloosahatchee River Basin are now below their historic conditions.  Water levels in the Lower East Coast are now above below their historical averages – they experienced a sharp recovery this week as a result of local rainfall.  Water levels in the Upper East Coast remain above their historic averages and are close to their highest recorded values.  Surface and groundwater levels in Water Conservation Areas 1, 2 and 3 continue to remain above their historic averages this week – the highest recorded levels were within Water Conservation Areas 2 and 3.

 

All eleven water supply risk indicator parameters are now in the “low” risk category, including the CPC Precipitation Outlook, Palmer Index for Tributary Conditions, the Lake Okeechobee Seasonal and Multi-seasonal Net Inflow Forecast, and Water Conservation Areas 1, 2A and 3A.  The projected Lake Okeechobee Stage and LEC Service Areas 1, 2 and 3 (as a result of the removal of water restrictions) are now in the “low” risk category.

 

LORS2008 (Lake Okeechobee Regulation Schedule)

 

Stages in Lake Okeechobee (Lake) are now within the low sub-band.  Inflows from the tributary basins have continued to taper off and are currently in the normal category for the tributary hydrologic conditions.  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 maximum practical discharges to the south if desired or with minimal impact.

 

 

 

 

 

 

 

 

CC:      George Horne