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 28, 2008

 

SUBJECT:     Weekly Environmental Conditions for Systems Operations

 

Summary

 

Water depths on the restored Kissimmee River floodplain currently range from 0.5 to 1.4 feet and large numbers of wading birds are foraging there.  Lake Okeechobee stage is 14.89 feet NGVD, which is 0.02 foot lower than a week ago, 0.08 foot lower than a month ago, and 4.64 feet higher than it was a year ago.  Salinity conditions in the St. Lucie Estuary are considered to be fair based on the salinity preference of the oyster, Crassostrea virginica.  In the Caloosahatchee Estuary, salinity conditions are good in the upper estuary, good in San Carlos Bay and poor in the lower estuary.  WCA stages were essentially unchanged from last week except for WCA-2B which received 3.3 inches of rain.  Salinity increased slightly or remained stable across Florida Bay. Ten out of the eleven water supply risk indicator parameters are now in the “low” risk category.

 

On October 14th, the United States Army Corps of Engineers (USACE) initiated baseflow releases to both estuaries, targeting an overall average release of 450 cfs at S-79 to the Caloosahatchee River and 200 cfs at S-80 to the St, Lucie River.

 

Background

 

Dry and quite cool through Wednesday.  Much cooler air is arriving behind the passage of a secondary cold front.  Look for unseasonably cool temperatures with some record lows likely Wednesday morning over many sections of the District.  Then, deep layered high pressure will dominate with warmer temperatures arriving by Thursday along with some minor showers east by Friday.  Next chance for significant rainfall appears at least 10 days away.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.66 inches of rainfall to bring the 30 day total to 3.98 inches (124% of average) and the lower basin received approximately 0.60 inches to bring the 30 day total to 3.92 inches (127% of average).

 

Water levels in most of the upper basin lakes continue to closely follow their regulation schedules.  Stages in Lakes Kissimmee, Hatchineha and Cypress are now 0.8 feet below regulation schedule.

 

Discharge from Lake Kissimmee remained at approximately 300 cfs and discharge at S65C decreased from 450 cfs to 100 cfs.

 

Water depths on the floodplain currently range from 0.5 to 1.4 feet in general.  

Large numbers of wading birds are foraging on the floodplain.

From 10/21/08 to 10/28/08 dissolved oxygen (DO) concentrations in the Kissimmee River ranged from 0.89 mg/L to 8.71 mg/L and averaged 5.5 mg/L.


Lake Okeechobee

 

According to the Unites States Army Corp of Engineers (USACE) web site, Lake Okeechobee stage is 14.89 feet NGVD, which is 0.02 foot lower than a week ago, 0.08 foot lower than a month ago, and 4.64 feet higher than it was a year ago.  The current stage is 0.15 foot below the historical average for this date, and 0.91 foot above the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 638 cfs, with the greatest contributions from the S84 (331 cfs) and the S72 (201 cfs).  These reported inflows do not include approximately 300 cfs through the S65E and approximately 100 cfs from Fisheating Creek.  Total reported outflows are 708 cfs and include 497 cfs through the S308 and 205 cfs to the L8 at Canal Point.

 

Last week, field crews resampled 59 annual mapping grid cells that had submerged aquatic vegetation (SAV) in August prior to Tropical Storm Fay.  Plants were still present at 32 of the cells (compared to 37 cells in September) and 13 of the cells were too deep to sample (the same as in September).  The average secchi depth:total depth ratio was 0.35 (compared to 0.37 in September).

 

A survey was conducted last week to determine the status of large numbers of the endangered Okeechobee Gourd that became established on the southern islands during the drought.  Recent water level rises flooded and killed established plants, which typically senesce at this time of year anyway.  Large numbers of fruits (gourds) were located and the vegetation management group will be requesting a permit to transport these propagules to more suitable locations.

 

St. Lucie Estuary

 

Over the past week, discharge averaged 212 cfs at the S-80.  Discharge from the Lake at the S-308 averaged 361 cfs.  Provisional data indicated an average discharge of 69 cfs at the S-97 on C-23, and 131 cfs from the S-49 on C-24.  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)

2.96 (0.77)

3.71(0.83)

 

HR1 (North Fork)

4.81 (1.66)

9.49 (4.30)

 

Roosevelt Bridge

8.30 (4.41)

10.87 (5.52)

8.0 – 25.0

A1A Bridge

19.62 (16.32)

25.78 (23.90)

20.0 – 31.0

 

Compared with the previous week, average salinity increased from 2.2 ppt to 5.3 ppt throughout the estuary.  Bottom salinity at the A1A Bridge is within the preferred range and the surface salinity is close to the lower limit of the preferred range at the A1A Bridge.  Salinity at Roosevelt Bridge is within the preferred range.  Salinity conditions in the estuary are considered to be fair based on the salinity preference of the oyster, Crassostrea virginica, and the location in the estuary.

 

Caloosahatchee Estuary

 

During the last week, discharge averaged 849 cfs at the S-79, 275 cfs at the S-78, and 0 cfs at the S-77.  The concentration of chlorides at the Olga Plant was 55 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)

0.29 (0.26)

0.55 (0.27)

Route 31 Bridge

0.52 (0.27)

NR (0.28)

I-75 Bridge

0.82 (0.31)

1.99 (0.36)

Fort Myers Yacht Basin

4.46 (1.19)

7.32 (2.93)

Cape Coral Bridge

11.53 (6.78)

14.71 (10.03)

Shell Point

24.73 (21.36)

NR (22.48)

 

Salinity conditions in the upper estuary east of Fort Myers are good (30 day average at Fort Myers equals 1.46 ppt).

 

An increase in salinity 3-5 ppt occurred downstream of Fort Myers Yacht Basin.  Salinities at Cape Coral Bridge are still below the preferred ranges for both the oyster, Crassostrea virginica, and the seagrass, Halodule wrightii.  Therefore, conditions in the lower estuary are still considered poor.  Salinity at Shell Point indicates that conditions are good in San Carlos Bay.

 

Fish and Wildlife Research Institute (FWRI) reports that background concentrations of Karenia brevis, the Florida red tide organism, were detected this week in water samples collected along portions of Sarasota County and southern Lee County.  Monitoring data collected by the River, Estuary and Coastal Observing Network (RECON) of the Sanibel-Captiva Conservation Foundation (SCCF) indicated that over the last week, Chlorophyll concentrations were about 3.0-4.5 µg/L at Fort Myers and 1.5-3.5 µg/L at Shell Point.  The DO concentration at the two locations ranged from about 5-7 mg/L.

 

Water Conservation Areas

 

Rain was relatively heavy in the central regions of the Everglades Protection Area (EPA), especially in WCA-2B.  Pan evaporation of 1.18 inches was essentially the same as the rainfall, producing no net change in system volume.  Basin-level rainfall values for the week ending on 10-27-08 were:

 

RAIN:  WCA-1:           0.97 inches      WCA-3A:         1.25 inches

WCA-2A:         1.59 inches      WCA-3B:         0.69 inches

WCA-2B:         3.30 inches      ENP:               1.26 inches

 

Stage changes were essentially unchanged from last week, except for WCA-2B, where a high rainfall cell deposited 3.3 inches of rain.  Average basin stage changes for the week ending on 10-27-08 were:

 

Stage Change:            WCA-1:           0.04 foot                      WCA-3A:         -0.04 foot

WCA-2A:         0.08 foot                      WCA-3B:         0.02 foot

WCA-2B:         0.32 foot                      NESRS:          0.06 foot

 

Stage change compared to one month ago, throughout the Greater Everglades indicate that WCA-2A and WCA-3A have been getting slightly shallower, while the rest of the system has been getting slightly deeper.  The EPA is at a seasonal high in terms of depths.  The southern region of WCA-3A has 3.82 feet of water and is now 91 days above the tree island threshold of 2.5 feet.  The northern region of WCA-3A, on-the-other-hand, has only 2.33 feet of water and is no longer above the tree island threshold.  Other high depth regions include: WCA-1, 2A, 2B, central 3A, and northern 3B.  So far, none of these regions have exceeded the 120 day maximum duration for tree islands.

With the end of the rainy season, stages are expected to drop gradually to 2.5 feet or below, except in southern WCA-3A, before tree islands are expected to experience flooding stress.

 

Stages in WCA-1 are slightly below regulation depths.  WCA-2A stages are declining but are still above their regulation stage, as they have been for more than one full year.  The stage in WCA-3A has stabilized at last week’s level and remains over a foot above regulation, continuing an exceedance that began in mid-July.

 

Everglades National Park

 

Stages in Everglades National Park (ENP) were up slightly or unchanged last week.  Water levels in Shark River Slough, Craighead Pond, and the ENP panhandle were up by approx. 0.5 inches over the 7-day period.  Taylor Slough Bridge water level was unchanged.  Wetland stages across much of ENP remain well above their seasonal averages, with the exception of Craighead Pond where the water level is at its seasonal average.

 

Salinity increased slightly or remained stable across Florida Bay last week.  The eastern Bay saw salinity remain largely unchanged (low 20s – Lake Madeira platform; mid 20s – Long Sound; low 30s – Duck Key) but increased to the mid 20s at Highway Creek.  The 30-day moving average salinity at the Taylor River platform (used for tracking the Florida Bay MFL) declined slightly last week from 5.6 psu (10/19) to 5.0 psu (10/26).  In the north-central Bay, salinity increased slightly to the mid 20s in Terrapin Bay, and following a mid-week spike to the mid 20s, salinity fell into the upper teens upstream in McCormick Creek.  The central Bay platform at Whipray Basin saw another week of salinity holding steady near 35 psu.  To the west, salinity remained near seasonal concentrations in the upstream reaches of Shark River Slough (Tarpon Bay platform – salinity nearly fresh at < 1 psu).

 

Water Supply

 

Water levels declined slightly across most of the District this week, as a result of relatively light rainfall.  Water levels in the upper and lower Kissimmee Basin (KB) are now near their average conditions for their respective periods of record.  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 well above their historical averages although wells in the upper Caloosahatchee River Basin continue to be below their average historic conditions.  Water levels in the Lower East Coast are now near or slightly above their historical averages.  Water levels in the Upper East Coast remain above their historic averages.  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 1 and 2.  Water levels in the area of Everglades National Park continue to remain above their historic averages for the period of record.

 

Ten out of the 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 Lower East Coast (LEC) Service Areas 1, 2 and 3 (as a result of the removal of water restrictions) are now in the “low” risk category.  The Lake Okeechobee Seasonal Net Inflow Forecast has turned from “low” to “medium” risk, on the anticipation of the coming dry season.


LORS2008 (Lake Okeechobee Regulation Schedule)

 

Stages in Lake Okeechobee are now within the low sub-band.  Tributary inflows are currently in the normal 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 maximum practical discharges to the south if desired or with minimal impact.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CC:      George Horne