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 18, 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

 

Quite cool Tuesday and Wednesday before a warming trend begins on Thursday.  A strong, dry cold front will swing quickly through the District on Tuesday.  Look for associated winds to kick up and temperatures to begin declining Tuesday afternoon.  Tuesday night will be breezy and cold with some record lows possible north through west of Lake Okeechobee.  It will remain chilly and breezy behind the front Wednesday.  High pressure will begin to build in more strongly from the west by Thursday.  Resulting northeast winds will moderate temperatures through the weekend with a chance for some minor showers east.  Next chance for significant rainfall is at least 10 days away.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.50 inches of rainfall to bring the 30 day total to 1.35 inches (53% of average) and the lower basin received approximately 0.10 inches to bring the 30 day total to 0.80 inches (33% of average).

 

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

 

Discharge from Lake Kissimmee remained at approximately 300 cfs and discharge at S65C increased from 180cfs to approximately 400 cfs.

 

Water depths on the floodplain currently range from 0.5 to 1.0 foot in the south end of the restoration area and in low-lying areas.

 

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 onto the floodplain around the active backfilling in an effort to control turbidity.  The contractor expects to widen/clean out the flow-way around the construction area and decrease the head difference soon.

 

The post-Tropical Storm Fay recession rate on the floodplain is approximately 2.2 feet/30 days, about twice as fast as our target rate.

 

From 11/4/08 to 11/18/08 dissolved oxygen concentrations in the Kissimmee River ranged from 5.0 mg/L to 7.9 mg/L and averaged 6.4 mg/L.

 

Lake Okeechobee

 

According to the Unites States Army Corp of Engineers (USACE), Lake Okeechobee stage is 14.49 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.  The current stage is 0.44 foot below the historical average for this date, and 0.63 foot above the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 306 cfs and include contributions from S65E (286 cfs) and Fisheating Creek (20 cfs).  Total reported outflows are 1213 cfs and include 491 cfs through the S308, 424 cfs through the S77, and 298 cfs to the L8 at Canal Point.

 

The monthly submerged-aquatic-vegetation (SAV) survey was completed during the first week of November and 10 of the 30 sites sampled had plants (compared to 16 of 35 in October).  The macroalga Chara has declined in coverage at the south end of the lake and has disappeared from Pelican Bay.  Water clarity was similar to last month with an average secchi depth:total depth ratio of 0.33 (compared to 0.36 last month).  Tannic conditions remain in the north around King’s Bar and in Fisheating Bay.

October water-quality monitoring results are now available.  All 25 monitoring stations had sufficient water for sampling.  Total phosphorus averaged 155 ppb lakewide (compared to 128 ppb in September) and 138 ppb at nearshore stations (compared to 118 ppb in September).  Total suspended solids averaged 25 ppm lakewide (compared to 20 ppm in September) and 12 ppm at nearshore stations (compared to 11 ppm in September).

October phytoplankton monitoring was completed at 7 of the 9 sites and results are now available.  Chlorophyll a concentrations averaged 12 ppb and ranged between 3 ppb (Kissimmee) and 25 ppb (Taylor Creek).  Microcystin levels were at or below the 0.2 ppb detection limit at all sites.

 

Last week crews surveyed the recently flooded scraped areas at Okeetantie Park and the Jaycee Park Pier on the north end of the lake.  They reported approximately 40–50% reestablishment by native vegetation at both sites.  The most common native plants near the Pier included three square (Scirpus americanus), Kissimmee grass (Paspalidium geminatum) and smartweed (Polygonum hydropiperoides).  Torpedograss has also established in shallow areas near the parking lot near the Pier.  Smartweed and Cattail were the most common emergent plants at the Okeetantie Park site.  Hydrilla was present at both sites and the invasive exotic plant Luziola subintegra, which was previously reported only in Fisheating Bay, was also found near the Jaycee Park Pier.  To date, this is the farthest north this plant has been observed.


St. Lucie Estuary

 

Over the past week discharge averaged 215 cfs at S-80. Discharge from the Lake at S-308 averaged 562 cfs.  Provisional data indicated an average discharge of 0 cfs at S-97 on C-23, and 165 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)

5.31 (3.35)

6.61 (5.41)

 

HR1 (North Fork)

11.27 (9.76)

12.58 (15.38)

 

Roosevelt Bridge

12.68 (11.82)

14.06 (14.98)

8.0 – 25.0

A1A Bridge

22.68 (18.66)

25.09 (24.44)

20.0 – 31.0

 

Salinity increased throughout the estuary with a slight decrease in bottom salinities at HR1 and the Roosevelt Bridge during the past week.  Salinity at the Roosevelt and A1A Bridges 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 433 cfs at S-79, 253 cfs at S-78, and 333 cfs at S-77.  The concentration of chlorides at the Olga Plant was 65 ppm Monday.  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)

4.34 (4.31)

4.33 (4.47)

Route 31 Bridge

5.14(3.70)

5.46 (5.95)

I-75 Bridge

5.58 (3.30)

6.59 (9.41)

Fort Myers Yacht Basin

9.44 (6.18)

9.65 (13.72)

Cape Coral Bridge

17.05 (12.77)

17.80 (16.24)

Shell Point

27.97 (23.53)

27.50 (24.14)

 

Salinity increased throughout the estuary except for bottom salinities above Fort Myers.  Salinity conditions in the upper estuary east of Fort Myers are good (30 day average at Fort Myers = 5.81 ppt).  Salinities at the Cape Coral Bridge are within the preferred range for the oyster, Crassostrea virginica, and well within the range tolerated by the 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 red tide organism, Karenia brevis.  Additional samples, collected offshore of Sanibel Island in Lee County, also contained no K. brevis.  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 and 27 µg/L at Fort Myers and 1.6 to 4.0 µg/L at Shell Point.  The dissolved oxygen concentration at the two locations ranged from 5.0 to 9.9 mg/L.

 

Water Conservation Areas

 

Stage dropped significantly over the last two weeks everywhere due to evapotranspiration and structure openings.  Average basin weekly stage changes for the week ending on 11-18-08 were:

 

Stage Change:            WCA-1:           -0.15 foot         WCA-3A:         -0.20 foot

WCA-2A:         -0.28 foot         WCA-3B:         -0.10 foot

WCA-2B:         -0.13 foot         NESRS:          -0.08 foot

 

The Everglades Protection Area is still at a seasonal high, in terms of depths. The southern region of WCA-3A has 3.42 feet of water and is now 112 days above the tree island threshold of 2.5 feet.  The northern region of WCA-3A at gage 63 has 2.43 feet of water and is no longer above the tree island threshold.  Other high depth regions include: 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 within the A1 regulation depths.  WCA-2A stage has dropped some two feet in the last two months and is only slightly above regulation stage.  Thirteen months above regulation in WCA-2A is about to come to an end. The stage in WCA-3A is about 0.5 foot above regulation, continuing an exceedance that began in mid-July.

 

Everglades National Park

 

Stages in Everglades National Park (ENP) declined last week.  Water levels in Shark River Slough and the ENP panhandle decreased by 0.5 inches and 0.4 inches, respectively.  In southern Taylor Slough, water levels at the Taylor Slough Bridge and in Craighead Pond decreased by 0.4 inches and 1.1 inches, respectively.

 

Salinity remained mostly steady 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 declined slightly from the mid 20s to the low 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) declined last week from 1.6 psu (11/9) to 1.4 psu (11/16).  In the northcentral Bay, salinity held steady in the mid 20s in Terrapin Bay, and following a mid-week spike into the upper 20s, salinity dropped back into the upper teens in McCormick Creek.  The central bay platform at Whipray Basin saw salinity decline slightly into the low-mid 30s.  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 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 of the 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.

 

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 Coast 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