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 2, 2008

 

SUBJECT:     Weekly Environmental Conditions for Systems Operations

 

Summary

 

Water depths on the southern end of the restored Kissimmee River floodplain currently range from 0.5 to 1 foot and dissolved oxygen concentrations are good.  Lake Okeechobee stage is 14.49 feet NGVD, which is 0.14 foot lower than a week ago, 0.47 foot lower than a month ago, and 4.18 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.  WCA stages dropped significantly due to the lack of rainfall and salinity values remained steady 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.  These releases are continuing.

 

Background

 

Current conditions are dry and cool.  A secondary cold front is exiting the southeast coast Tuesday morning.  Some clouds will linger behind this front until the associated upper level trough passes through late Tuesday afternoon and cool weather will hang on through Wednesday.  Otherwise, weak high pressure will dominate through the remainder of the work week.  A weak cold front arrives Saturday with little or no rainfall.  The next chance for appreciable rainfall appears the middle of next week.  The next ten days precipitation outlook is below average with moderate confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.43 inches of rainfall to bring the 30 day total to 1.11 inches (45% of average) and the lower basin received approximately 0.43 inches to bring the 30 day total to 0.63 inches (29% of average).  Stage in Lakes Kissimmee, Hatchineha and Cypress is now 1.26 foot below regulation schedule and stage in Lakes Tohopekaliga and East Tohopekaliga is approximately 0.5 foot below regulation schedule.

 

Florida Fish and Wildlife Conservation Commission (FWC) will be conducting hydrilla treatments on Lake Toho between mid-November and mid-January.

 

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 7-8 feet higher than south of the backfilling due to water being conveyed around the active construction.  In the event of increased inflows through S65A, culverts can be opened to pass additional water around/through the construction area.

 

From 11/25/08 to 12/2/08 dissolved oxygen concentrations in the Kissimmee River ranged from 7.2 mg/L to 8.9 mg/L and averaged 8.0 mg/L.

 

Lake Okeechobee

 

According to the United States Army Corp of Engineers (USACE) web site, Lake Okeechobee stage is 14.28’ NGVD, which is 0.05 foot lower than a week ago, 0.47 foot lower than a month ago, and 4.03 feet higher than it was a year ago.  The current stage is 0.53 foot below the historical average for this date, and 0.53 foot above the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 139 cfs and are limited to contributions from S65E.  Outflows of 208 cfs are reported to the L8 at Canal Point.  Releases also continue to the estuaries (S308 and S77), but current flows are not reported.

 

The monthly submerged-aquatic-vegetation (SAV) survey is being performed this week.  The macroalga Chara continues to decline in coverage at the south end of the lake and was found at only 1 site.  Water clarity has also declined with an average secchi depth:total depth ratio of 0.22 (compared to 0.33 last month).

 

St. Lucie Estuary

 

Over the past week discharge averaged 214 cfs at S-80.  Discharge from the Lake at S-308 averaged 513 cfs.  Provisional data indicated an average discharge of 62 cfs at S-97 on C-23, and 0 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 (S. Fork)

3.14 (NR)

9.62 (7.12)

 

HR1 (N. Fork)

14.98 (14.19)

16.95 (16.97)

 

Roosevelt Bridge

14.89 (15.09)

17.27 (17.27)

8.0 – 25.0

A1A Bridge

23.16 (24.89)

25.09 (26.11)

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.

 

Caloosahatchee Estuary

 

During the last week, discharge averaged 431 cfs at S-79, 293 cfs at S-78, and 600 cfs at S-77.  The concentration of chlorides at the Olga Plant was 54 ppm on November 30th.  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)

4.81 (3.39)

4.92 (3.41)

Rt. 31 Bridge

4.60 (3.57)

5.89 (3.85)

I-75 Bridge

4.92 (3.93)

7.60 (5.60)

Ft. Myers Yacht Basin

11.00 (7.97)

13.90 (11.13)

Cape Coral Bridge

18.71 (16.69)

20.19 (18.22)

Shell Point

29.82 (26.89)

28.75 (27.48)

 

Salinity increased throughout the estuary.  Salinity conditions in the upper estuary east of Fort Myers are good (30 day average at Ft. Myers equal 8.3 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 6.5 µg/L at Ft. Myers and 1.0 to 2.0 µg/L at Shell Point.  The dissolved oxygen (DO) concentration at the two locations ranged from 5.8 to 9.0 mg/L

 

Water Conservation Areas

 

Stage dropped at rates considered healthy in WCA-1, WCA-2A and WCA3A.  However, structure openings were very effective in maintaining water levels in WCA-3B and increasing water levels in Northeast Shark River Slough.  These structure openings were implemented to reduce the high water levels in southern WCA-3A and supply maximum inflows to Shark River Slough and Taylor Slough. Average basin weekly stage changes for the week ending on 12-2-08 were:

 

Stage Change:            WCA-1:           - 0.03 ft            WCA-3A:         - 0.15 ft

WCA-2A:         - 0.15 ft            WCA-3B:         + 0.07 ft

WCA-2B:         + 0.08 ft           NESRS:          + 0.21 ft

 

Despite the fact that some regions are increasing slightly due to structure openings, the EPA is no longer at seasonal high water levels.  Water levels are now receding at rates considered typical of a healthy Everglades (i.e., - 0.05' to - 0.016').  As a result, almost all areas that were once above the tree island threshold of 2.5 feet, are now below.  The central region of WCA-3A is expected to be below 2.5 feet by next week.  Water levels will remain high at Gage 99 in WCA-2B, where it is ponded and perpetually deep, and never has supported tree island habitat.  Water levels will also remain high in southern WCA-3A because of restricted flow across Tamiami Trail.

 

Landscape scale depth changes indicate that WCA-3A has changed considerably over the last two months, while WCA-2A changed considerably over the last one month, and WCA-1 has not changed very much.  All three WCA’s are close to the regulation schedule.  WCA-2A stage dropped a quarter of a foot and has been dropping very quickly over the last two months.  As a result, thirteen months above regulation in WCA-2A has come to an end, and the exceedance that began in mid-July in WCA-3A will end soon.


Everglades National Park

 

Stages in Everglades National park (ENP) displayed a general downward trend last week.  Water levels in Shark River Slough and the ENP panhandle deceased by 0.2 inches and 0.4 inches, respectively.  In southern Taylor Slough, water levels at the Taylor Slough Bridge increased by 0.4 inches and decreased by 1.0 inch at Craighead Pond.

 

Salinity displayed a general stable trend in Florida Bay (Bay) last week.  In the eastern Bay, salinity was stable in the mid 20s nearshore (Long Sound) and low 30s further into the Bay (Duck Key).  Salinity was stable 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) remained unchanged at 1.4 psu (11/23 and 11/30).  To the west, salinity in the upstream reaches of Shark River Slough ticked back down to ~ 1 psu at the Tarpon Bay platform.

 

Water Supply

 

Water levels continued to decline 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 or slightly below 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 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, although some wells experienced subtle declines.  Surface and groundwater levels in Water Conservation Areas 1, 2 and 3 continue to remain at or slightly 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.

 

Eight out of the eleven water supply risk indicator parameters remain in the “low” risk category, including the projected LOK Stage, the LOK Multi-Seasonal Net Inflow Forecast,  Water Conservation Areas 1, 2A and 3A and LEC Service Areas 1, 2 and 3 (no restrictions).

 

The CPC Precipitation Outlook, Palmer Index for Tributary Conditions, and the Lake Okeechobee Seasonal Net Inflow Forecast are now in the “medium” risk category, anticipating seasonally dry conditions.

 

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.

 

 

 

 

 

 

 

 

 

CC:      George Horne