MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       February 12, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

No Lake Okeechobee regulatory releases to the south or estuaries are recommended.

 

Background

 

Showers and thunderstorms today and Wednesday.  A developing low pressure system over the central Gulf of Mexico will move northeastward and pull an old front back north over the District.  Expect widespread showers and thunderstorms with locally heavy rainfall amounts to move over the District from the south and west during the day today and continuing tonight.  The exiting low will push a cold front southward through the District Wednesday bringing showers and thunderstorms mainly over the southern half of the District Wednesday.  Dry air will then settle in for Thursday before the front returns north again and brings showers east.  The next ten days precipitation outlook is above average with moderate confidence.

 

Kissimmee Watershed

 

Over the last 7 days, the upper Kissimmee Basin received 0.21 inches of rainfall to bring the 30-day total to 3.12 inches, which was 127% of the long term average, and the lower basin received 0.07 inches to bring the 30-day total to 1.08 inches, which was 54% of average.  Water levels in the upper basin lakes are at or below their regulation schedules.

 

Lake Kissimmee (S-65) continued discharging approximately 250 cfs to the Kissimmee River. Releases of 200 cfs are being made from Lake Toho (S-61).  Releases from Lake Gentry (S-63) are likely to begin today.  No other releases are being made in the upper basin.

 

Snail kites have begun nesting in the upper basin.  Lake Toho has several active nests.  Flow has been reestablished to the Kissimmee River for 202 days (S-65 re-opened on 07/18/07).  Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 4.6 mg/L to 9.1 mg/L with an average of 7.7 mg/L.

 

Aerial surveys were conducted last month (January 10) for water birds on the Kissimmee River floodplain.  Within the area affected by the restoration project, wading birds (largely glossy ibis, great egrets, great blue heron, and white ibis) had a density of 22.7 birds/km², and waterfowl (largely mottled ducks and blue-winged teal) had a density of 4.9 birds/km².  In the area unaffected by the restoration project, wading birds (largely great egret, white ibis, and glossy ibis) had a density of 3.7 birds/km², and waterfowl (only blue-winged teal) occurred at higher densities of 12.3 birds/km² because of high concentrations at two isolated wetlands

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.98’ NGVD, which is 0.07’ lower than a week ago and 0.14’ lower than a month ago.  The current stage is 1.50’ lower than it was a year ago and 4.68’ below its historical average for this time of year.  Inflows from the Kissimmee River (S65E) continue at approximately 250 cfs and outflows through the S354 (55 cfs) and S77 (96 cfs) also are reported.

 

In January, 20 of the 27 water quality sampling sites had sufficient water for sampling.  Preliminary lake wide TP averaged 232 ppb and TSS averaged 104 mg/L.  These concentrations are higher than those measured in December (TP = 97 ppb, TSS = 21 mg/L).  Preliminary average TP at near shore sites increased from 54 ppb in December to 117 ppb in January and TSS increased from 10.5 mg/L to 35.8 mg/L.

 

The monthly submerged-aquatic-vegetation (SAV) survey was completed last week.  The macroalga Chara remains the dominant SAV species and was found at 8 of the 29 sites sampled.  This distribution is lower than that reported in December, with slight reductions in the density of Chara. Water clarity decreased with secchi depths less than 50% of total depths at 10 of the 29 sites sampled. One species of vascular SAV, Vallisneria americana, continues to be present in very low density at a few sites around King’s Bar on the northern shoreline and a few sites along the western shoreline.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  No discharge occurred at S-97 on the C-23 Canal or at S-49 on the C-24 canal.  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)

12.9 (11.8)

15.6 (15.5)

 

HR1 (N. Fork)

 16.4 (16.5)

18.7 (19.0)

 

Roosevelt Bridge

 22.0 (19.5)

22.5 (20.5)

8.0 – 25.0

A1A Bridge

 28.0 (25.7)

28.9 (27.3)

20.0 – 31.0

 

Average salinity increased during the past week at most sites.  Both the surface and bottom salinity are in the preferred range at the Roosevelt Bridge, and at the A1A Bridge.  Based on the salinity tolerances of the oyster, Crassostrea virginica, salinity conditions in the estuary are good.  The current surface salinity of 22.0 ppt at the Roosevelt Bridge is 6 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

 

Caloosahatchee Estuary

 

No discharge occurred at S-79 last week.  The concentration of chlorides at the Olga Plant is 175 mg/l.  Average salinity changed little over the past week.  Weekly average salinities for specific sites are given below in parts per thousand (ppt).  Current weekly averages (in bold) may be compared to last week’s data (in parenthesis).

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

 17.6 (17.0)

 17.7 (17.6)

Rt. 31 Bridge

18.1 (17.3)

19.8 (20.1)

I-75 Bridge

NA (NA)

 21.2 (21.1)

Ft. Myers Yacht Basin

 23.9 (24.0)

 23.8 (24.2)

Cape Coral Bridge

 27.1 (26.2)

 30.8 (30.8)

Shell Point

34.3 (34.5)

 35.4 (35.9)

Salinity at the Ft. Myers surface sensor remains above the 1-day MFL criterion of 20 ppt.  The current surface salinity of 17.6 ppt at S-79 is 2.4 ppt below the maximum weekly average of 20.0 ppt achieved in May 2001 during the 2000 – 2001 drought.  Salinity at the Cape Coral Bridge is near (surface) or above (bottom) the upper limit of the optimal range for the oyster, Crassostrea virginica.  Conditions in the upper estuary east of Ft. Myers are poor due to high salinity.  Based on the salinity tolerances of oysters conditions downstream of Cape Coral are fair.

 

FWRI reports that no Karenia brevis, the Florida red tide organism, was detected this week in water samples collected alongshore between Pinellas and Monroe counties  Additional samples collected offshore of the Florida Keys also contained no K. brevis.

 

Water Conservation Areas

 

Good dry-season recession rates dominate the entire region.  Water depths for water bird foraging is good in WCA-2A, northern WCA-3A and Shark River Slough. Stages in WCA-1 remain slightly below Regulation, WCA-2A remains above regulation, and WCA-3 stages continue to be significantly below regulation

 

Everglades National Park

 

Everglades National Park (ENP) wetland water levels continued to drop in response to low precipitation.  Water level at Taylor Slough Bridge dropped by 1.8” over the 7 day period (not an unusual decline for this area), falling to nearly 2’ below ground surface.  Shark River Slough. (station P33) and southern Taylor Slough (at Craighead Pond) also posted declines of nearly 1” and 0.8”, respectively.  January water levels in all areas of ENP were well below where they have been over the past 10 years time and, lowest over this period of record (water year 1997 – 2007) at Taylor Slough Bridge (TSB) & P33 in SRS.  For these northern stations (TSB & P33) January 2008 water levels were similar to where they were in Jan. 1989, the beginning of the last extreme drought in S. FL.

 

Salinity concentrations remained stable or increased slightly in Florida Bay last week.  At the mouth of Taylor River salinity read just above 20 psu for much of the week.  The 30 day moving average concentration (used to track the MFL criterion) is still low at 5.9 psu as of Sunday, 2/10.  Whipray Basin salinity has started to slowly increase, up to just over 33 psu as of Sunday, 2/10.  As a whole these salinity concentrations are still near seasonal norms.  The exception to this trend is out west, in the SRS outflow at Tarpon Bay, where salinity remains above its seasonal average, measuring near 17 psu as of Sunday 2/10.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast decreased on average this past week, and remain below their historical average conditions for this time of year.  Water levels in the Lower East Coast are still near or slightly above their historical averages and most wells recorded modest decreases in water levels this past week.  Water levels in the Upper East Coast declined this past week, particularly in the St. Lucie Agricultural Area, but remain above their historic averages.  Surface and groundwater levels in Water Conservation Areas 1 and 2 are now slightly below their historic averages.  Water levels in WCA 3A continue to remain below their historic averages and were somewhat lower this week.  Water levels in the southernmost portion of Miami-Dade County are now below average historic conditions.

 

Six out of eleven water supply risk measures are in the “high” risk category including the projected Lake Okeechobee Stage (SSM), the Palmer Index for Tributary Conditions, the CPC Precipitation Outlook, and Lower East Coast Service Areas 1, 2 and 3.

 

One change from last week is the LOK Seasonal Net Inflow changed from high to medium risk.  The LOK Multi-Seasonal Net Inflow Forecasts remains at “medium” risk this week.  Water Conservation Areas 1 and 2A continue to be in the “low” risk category and Water Conservation Area 3A remains at “medium” risk.

 

Chlorides at the Olga WTP on the Caloosahatchee River are now at 175 ppm and the plant is operational

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake Okeechobee stage remains in the Water Shortage Management zone and is unlikely to move back into Zone E in the next several months during the persistent La Niña climactic conditions.

 

 

 

 

 

 

 

 

 

 

CC:   George Horne