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:                        November 4, 2008

 

SUBJECT:     Weekly Environmental Conditions for Systems Operations

 

Summary

 

Water depths on the restored Kissimmee River floodplain currently range from 0.5 to 1 foot and dissolved oxygen concentrations are good.  Lake Okeechobee stage is 14.74 feet NGVD, which is 0.15 foot lower than a week ago, 0.23 foot lower than a month ago, and 4.38 feet higher than it was a year ago.  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 good in the upper estuary, good in San Carlos Bay and poor in the lower estuary.  WCA stages dropped significantly due to the lack of rainfall and salinity values fluctuated 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

 

Mainly dry and warm through Saturday morning.  Double barreled low pressure systems are developing off the east and southeast coast of the United States, respectively.  Resultant drier air that is filtering down the peninsula will mix out the low stratus cloud to yield a warm and dry afternoon.  High pressure will then dominate the remainder of the week.  A weak cold front arrives Saturday night, but little rainfall is expected.  The next chance for significant rain is about a week away.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.19 inches of rainfall to bring the 30 day total to 4.02 inches (146% of average) and the lower basin received approximately 0.10 inches to bring the 30 day total to 3.15 inches (121% of average).

 

Stage in Lakes Kissimmee, Hatchineha and Cypress is now 1 foot below regulation schedule and stages in Lakes Tohopekaliga and East Tohopekaliga are approximately 0.5 foot below regulation schedule.

 

Discharge from Lake Kissimmee remained at approximately 300 cfs and discharge at S65C increased from100 cfs to approximately 180 cfs.  Water depths on the floodplain currently range from 0.5 to 1.5 feet in general.

 

The post-Tropical Storm Fay recession rate on the floodplain is approximately 2.4 feet/30 days.

 

From 10/28/08 to 11/4/08 dissolved oxygen (DO) concentrations in the Kissimmee River ranged from 5.4 mg/L to 8.5 mg/L and averaged 6.4 mg/L.

Lake Okeechobee

 

According to the Unites States Army Corp of Engineers (USACE) Lake Okeechobee stage is 14.74 feet NGVD, which is 0.15 foot lower than a week ago, 0.23 foot lower than a month ago, and 4.38 feet higher than it was a year ago.  The current stage is 0.29 foot below the historical average for this date, and 0.78 foot above the simulated historical average for the current regulation schedule.  Total reported inflows are 233 cfs, and includes contributions from S71 (48 cfs), S72 (163 cfs), and Fisheating Creek (22 cfs).  These reported inflows do not include approximately 150 cfs through S65E.  Total reported outflows are 623 cfs and include 419 cfs through the S308 and 199 cfs to the L8 at Canal Point.

 

Field sampling during the past week indicates that water-quality and biological conditions are similar to previous weeks.  Water clarity along the western shoreline remains fair, with secchi depth:total depth ratios of 0.3 to 0.4, and locally dense areas of Vallisneria persist in the Fisheating Bay-Harney Pond area.

 

St. Lucie Estuary

 

Over the past week, discharge averaged 151 cfs at S-80.  Discharge from the Lake at S-308 averaged 399 cfs.  Provisional data indicated an average discharge of 18.5 cfs at S-97 on C-23, and 174 cfs from 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)

2.21 (2.96)

2.96 (3.71)

 

HR1 (North Fork)

9.07 (4.81)

14.42 (9.49)

 

Roosevelt Bridge

10.50 (8.30)

12.99 (10.87)

8.0 – 25.0

A1A Bridge

19.80 (19.62)

25.14 (25.78)

20.0 – 31.0

 

Salinity increased in the North Fork and at the Roosevelt Bridge during the past week.  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 good based on the salinity preference of the oyster, Crassostrea virginica, and location in the estuary.

 

Caloosahatchee Estuary

 

During the last week, discharge averaged 527 cfs at S-79, 51 cfs at S-78, and 0 cfs at S-77.  The concentration of chlorides at the Olga Plant was 53 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)

0.71 (0.29)

1.28 (0.55)

Route 31 Bridge

1.05 (0.52)

1.18 (NR)

I-75 Bridge

1.18 (0.82)

2.31 (1.99)

Fort Myers Yacht Basin

4.05 (4.46)

6.85 (7.32)

Cape Coral Bridge

11.95 (11.53)

13.86 (14.71)

Shell Point

23.09 (24.73)

NR (NR)

Salinity conditions in the upper estuary east of Fort Myers are good (30 day average at Fort Myers equals 2.35 ppt).

 

Salinity remained about the same 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, southern Lee and Collier counties.  In addition, very low to low concentrations were detected in water samples collected from Marco Island in Collier County.  No impacts have been reported.  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 ranged between 3.5 and 5.5 µg/L at Fort Myers and 1.5 to 4 µg/L at Shell Point.  The DO concentration at the two locations ranged from 6 to 8.5 mg/L.

 

Water Conservation Areas

 

Rain was very light throughout the Everglades Protection Area (EPA).  The pan evaporation of 1.2 inches was slightly greater than last week and significantly greater than rainfall, producing a precipitation deficit for the week.  Basin-level rainfall values for the week ending on 11-04-08 were:

 

RAIN:              WCA-1:           0.09 inches      WCA-3A:         0.02 inches

WCA-2A:         0.16 inches      WCA-3B:         0.03 inches

WCA-2B:         0.22 inches      ENP:               0.03 inches

 

Stage dropped significantly from last week everywhere due to evapotranspiration and structure openings.  Average basin stage changes for the week ending on 11-04-08 were:

 

Stage Change:            WCA-1:           -0.11 foot         WCA-3A:         -0.20 foot

WCA-2A:         -0.28 foot         WCA-3B:         -0.17 foot

WCA-2B:         -0.17 foot         NESRS:          -0.14 foot

 

The EPA is still at a seasonal high, in terms of depths.  The southern region of WCA-3A has 3.67 feet of water and is now 98 days above the tree island threshold of 2.5 feet.  The central region of WCA-3A has 3.0 feet of water and is now 84 days above the tree island threshold of 2.5 feet.  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 down last week.  Water levels in Shark River Slough, the ENP panhandle, and Taylor Slough Bridge all decreased by approximately 1.4 inches.  Craighead Pond water level decreased by 0.5 inches.

Salinity increased, decreased, or remained stable across Florida Bay last week.  The eastern Bay saw salinity increase slightly at the Little Madeira platform (mid 20s), decrease at Long Sound (mid 20s) and Highway Creek (approximately 20 psu), and remain stable at Duck Key (mid 30s).  The 30 day moving average salinity at the Taylor River platform (used for tracking the Florida Bay MFL) declined last week from 5.0 psu (10/26) to 2.1 psu (11/2).  In the northcentral Bay, salinity decreased into the upper teens in Terrapin Bay and into the mid teens at McCormick Creek.  The central Bay platform at Whipray Basin saw salinity hold steady near 34 psu.  To the west, salinity remains nearly fresh in the upstream reaches of Shark River Slough (Tarpon Bay platform – salinity at less than 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 Multi-seasonal Net Inflow Forecast, and Water Conservation Areas 1, 2A and 3A.  The projected Lake Okeechobee Stage and Lower East Cost 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 remains at “medium” risk in advance of the upcoming 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