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:           December 9, 2008

 

SUBJECT:    Weekly Environmental Conditions for Systems Operations

 

Summary

 

The restored Kissimmee River floodplain is essentially dry at this time dissolved oxygen concentrations are good.  Lake Okeechobee stage is 14.16 feet NGVD, which is 0.12 foot lower than a week ago, 0.53 foot lower than a month ago, and 3.98 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 good in the lower estuary.  All three Water Conservation Areas are close to or at their regulation schedule.  Salinity values remained steady across Florida Bay.  Groundwater levels are declining due to the lack of rainfall.

 

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.  Based on the lack of benefit to the St. Lucie Estuary from the 200 cfs release, it is suggested that this be discontinued.  Base flow releases to the Caloosahatchee Estuary should be increased to 600 cfs.

 

Background

 

It is warmer with some limited shower activity Tuesday and Wednesday, with showers and thunderstorms Thursday.  Southeasterly winds are helping moisture to rebound over the area.  Some widely scattered shower activity should pop up mainly east Tuesday and Wednesday.  The next cold front is expected to move through the District Thursday and generate scattered showers and thunderstorms.  A post-frontal trough should keep some clouds and some spotty light showers over the District on Friday.  As this trough stalls over the District, expect some scattered showers mainly east Saturday.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.03 inches of rainfall to bring the 30 day total to 0.96 inches (38% of average) and the lower basin received approximately 0.03 inches to bring the 30 day total to 0.56 inches (27% of average).

 

Stage in Lakes Kissimmee, Hatchineha and Cypress is now 1.3 feet below regulation schedule and stage in Lakes Tohopekaliga and East Tohopekaliga is approximately 0.5 foot below regulation schedule.  Discharge from Lake Kissimmee is approximately 350 cfs and discharge at S65C is 350 cfs.

 

The floodplain in the restored section of the Kissimmee River is essentially dry except for the area immediately upstream of S65C and in isolated wetlands scattered throughout the floodplain.

 

Stage in C-38 north of the current backfilling project is approximately 7.5 feet higher than south of the backfilling due to water being conveyed around the active construction to limit turbidity issues.  In the event of increased inflows through S65A, culverts can be opened to pass additional water around/through the construction area.

 

Wading bird numbers were down significantly from October.  Most of the birds were observed in Pool B in one large flock at the south end of the backfilling construction area on the west side of C-38, in the large wet prairie area within the Bombing range fence.  This area would be dry if we were not conveying water onto the floodplain to bypass the active construction zone.

 

Dissolved oxygen  (DO) concentrations in the Kissimmee River were well above levels of concern over the past week.

 

Lake Okeechobee

 

According to the United States Army Corp of Engineers (USACE) web site, Lake Okeechobee stage is 14.16’ NGVD, which is 0.12 feet lower than a week ago, 0.53 foot lower than a month ago, and 3.98 feet higher than it was a year ago.  The current stage is 0.59 foot below the historical average for this date, and 0.48 foot above the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 179 cfs and include contributions from S65E (168 cfs) and Fisheating Creek (11 cfs).  Total reported outflows are 1517 and include baseflow releases towards the estuaries through the S77 (105 cfs) and S308 (333 cfs), water-supply releases through S351 (386 cfs), S352 (390 cfs), and S354 (291 cfs), and a small volume (12 cfs) to the L8 at Canal Point.

 

The monthly submerged-aquatic-vegetation (SAV) survey was completed last week and eight of the 24 sites sampled had plants (compared to 10 of 30 in November).  Vegetation was sparse or very sparse at all eight sites.  The macroalga Chara was found at one site in the south and one site in the west.  Two vascular species also were found, Vallisneria (two sites in the west and one in the north) and Ceratophyllum (four sites in the north).  Water clarity was the same as it was last month with an average secchi depth:total depth ratio of 0.33.

 

St. Lucie Estuary

 

Over the past week discharge averaged 214 cfs at S-80.  Discharge from Lake Okeechobee (Lake) at S-308 averaged 300 cfs.  Provisional data indicated that no discharge occurred at S-97 on C-23, and at 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 (S. Fork)

2.93 (3.14)

9.92 (9.62)

 

HR1 (N. Fork)

13.78 (14.98)

16.17 (16.95)

 

Roosevelt Bridge

14.85 (14.89)

17.17 (17.27)

8.0 – 25.0

A1A Bridge

23.37 (23.16)

25.17 (25.09)

20.0 – 31.0

 

Salinity changed only slightly 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.  Results for RECOVER oyster monitoring in November indicate low recruitment of spat, which is not unusual for this time of year.  However, because salinity is up, these late recruits are surviving.

Caloosahatchee Estuary

 

During the last week, discharge averaged 472 cfs at S-79, 233 cfs at S-78, and 227 cfs at S-77.  The concentration of chlorides at the Olga Plant was 58 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)

3.99 (4.81)

4.13 (4.92)

Rt. 31 Bridge

4.27 (4.60)

4.53 (5.89)

I-75 Bridge

4.69 (4.92)

6.38 (7.60)

Ft. Myers Yacht Basin

9.90 (11.00)

12.42 (13.90)

Cape Coral Bridge

17.83 (18.71)

19.09 (20.19)

Shell Point

27.98 (29.82)

27.01 (28.75)

 

Salinity decreased throughout the estuary.  Salinity conditions in the upper estuary east of Fort Myers are good (30 day average at Fort. Myers equals 9.5 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 Collier 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 3 and 5.5 µg/L at Fort Myers and 1.1 to 2.7 µg/L at Shell Point.  The DO concentration at the two locations ranged from 5.8 to 7.8 mg/L.

 

Water Conservation Areas

 

The lack of rainfall produced stage declines throughout the Water Conservation Areas (see WCA Stages spreadsheet).  Average basin weekly stage changes for this week varied from no change in Northeast Shark River Slough (NESRS) resulting from continued managed water releases from WCA-3 to nearly 0.2 ft in WCA-3A.  The variability of basin stage changes resulted from water management plus evaporation:

 

Stage Change: WCA-1:          - 0.06 ft           WCA-3A:       - 0.18 ft

WCA-2A:       - 0.10 ft           WCA-3B:        - 0.04 ft

WCA-2B:        - 0.02 ft           NESRS:          - 0.00 ft

 

Annual dry season recession rates are now being tracked.  Seasonal declines in the Everglades Protection Area ranging from - 0.05' to - 0.016' per week are considered Good.  Recession rates ranged from Good to Fair throughout the WCA basins.

 

Water depths are still locally above desired levels for tree islands at three gauges.  The central region of WCA-3A is now below 2.5 feet and only the southernmost station (gauge 65) is above it.  Water levels remain high at Gage 99 in WCA-2B in southern WCA-3A because of ponding.

 

All three WCA’s are close to or at the regulation schedule stages.  WCA-2 and WCA-3 no longer exceed these regulation stages.


 

Everglades National Park

 

Data transmission problems on Dec. 7 preclude reporting 7 day trends, so this week’s Everglades National Park (ENP) reports reflect six days of data (12/1 – 12/6).

 

Very little rain fell across ENP and Florida Bay last week.  Stations in ENP measured 0 – 0.2 inch of rainfall, and the basin-wide spatially-averaged weekly totals were 0.023 and 0.005 inch for the ENP and C-111 basins, respectively, as of yesterday.

 

Stages in ENP were generally stable last week.  Water level in Shark River Slough was unchanged but increased 0.7 inch in the ENP panhandle.  In southern Taylor Slough, water levels at the Taylor Slough Bridge and Craighead Pond decreased by 0.6 and 0.1 inch, respectively.

 

Salinity  was stable or dropped in Florida Bay over the week.  In the eastern Bay, salinity declined slightly to the low 20s near-shore at Long Sound; it remained steady in the low 30s further into the Bay (Duck Key) and in the mid 20s at the Little Madeira Bay platform.  The 30 day moving average salinity at the Taylor River platform used for tracking the Florida Bay MFL was up slightly from 1.4 psu (11/30) to 1.5 psu (12/6).

 

In the north central Bay, strong northeasterly winds last week allowed salinity to drop from the low 30s in Terrapin Bay and McCormick to the low 20s and upper teens, respectively.  Salinity was steady in the mid-30s at the central Bay platform in Whipray Basin.  To the west, salinity in the upstream reaches of Shark River Slough was steady at ~ 1 psu at the Tarpon Bay platform.

 

Water Supply

 

Water levels are continuing a declining trend across most of the District this week due to the light rainfall.  Water levels in the Kissimmee Basin are near their historic means or slightly below, and are decreasing gradually.  Upper East Coast groundwater levels are near their historic median levels and continuing a gradual decrease, with levels being higher closer to the coast.  Groundwater elevations in the Lower East coast are also near median levels and declining.  In western Miami-Dade County and the ENP, groundwater levels are slightly above historic means.  Lower West Coast groundwater levels remain at or above median values and are not showing the gradual declines that are occurring in other areas of the District.  Surficial, Lower Tamiami, and mid-Hawthorn aquifer levels are above median values for historic periods of record for the wells in the USGS real-time network.  Sandstone aquifer levels are at or just below median values.

 

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.  Based on the lack of benefit to the St. Lucie Estuary from the 200 cfs release, it is suggested that this be discontinued. Base flow releases to the Caloosahatchee Estuary should be increased to 600 cfs.

 

 

 

 

 

CC:      George Horne