MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       January 8, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Dry and warm through Thursday before some showers return for the weekend.  High pressure will dominate through Thursday, leaving dry and pleasant conditions.  Change begins on Friday when a cold front moves down into the panhandle of Florida before pushing through the peninsula Saturday/Sunday.  Some showers should accompany this progression.  There is still some evidence of more significant rains arriving in about 8-9 days, but confidence remains low.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

Over the last 7 days, the upper Kissimmee Basin received 0.09 inches of rainfall to bring the 30-day total to 0.54 inches, which was 23% of the long term average, and the lower basin received 0.27 inches to bring the 30-day total to 0.94 inches, which was 53% of average.  Water levels in all of the upper basin lakes, except Lake Toho, have continued to decline. All lakes are below regulation schedule.  The only releases being made in the upper basin are at S-65, which is discharging approximately 250 cfs.  Flow has been reestablished to the Kissimmee River for 167 days (S-65 re-opened on 07/18/07).  In the river channel of the Kissimmee River, the concentration of dissolved oxygen ranged from 3.9 mg/L to 7.1 mg/L (mean 6.0 mg/L) for the last seven days.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.13’ NGVD, which is 0.15’ lower than a week ago and 0.05’ lower than a month ago.  The current stage is 1.98’ lower than it was a year ago and 4.67’ below its historical average for this time of year.  Inflows from the Kissimmee River (S65E) continue at approximately 250 cfs and periodic outflows to the Lake Istokpoga Service Area are occurring through the G207 and G208.

 

Phytoplankton bloom monitoring was conducted on December 26th.  Six out of 9 monitoring stations had sufficient water for sampling.  No algal blooms were observed with the exception of light bloom formation at the Pahokee Marina.  No algal toxins were detected.  Chlorophyll and total P data from this trip are not yet available.

 

Monthly SAV monitoring is being conducted this week.  Slight reductions in the density of the macroalga Chara were reported at the south end of the lake on Monday despite continued good to excellent water clarity (secchi depths 50-100% of total depths).  No vascular SAV species were encountered.


St. Lucie Estuary

 

There were no releases through S-80 over the past week.  Discharge at S-97 on the C-24 Canal averaged 0.5 cfs.  There was negligible discharge at S-49 on the C-23 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)

9.3 (6.7)

11.2 (9.9)

 

HR1 (N. Fork)

13.3 (11.4)

15.7 (14.3)

 

Roosevelt Bridge

16.5 (14.2)

17.1 (16.1)

8.0 – 25.0

A1A Bridge

24.5 (23.1)

27.3 (27.0)

20.0 – 31.0

 

Salinity increased this week at all monitoring 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.

 

FWRI reports that along the East Coast, background concentrations of the red tide organism, Karenia brevis, were detected at Walton Rocks Beach (St. Lucie County) and Chastane Beach (Martin County).  All other samples collected between Brevard and Martin counties contained no K. brevis.

 

Caloosahatchee Estuary

 

No discharge occurred at S-79 last week.  The concentration of chlorides at the Olga Plant is 178 mg/l.  Average salinity increased in the upper estuary changed only slightly over the past couple of weeks.  Shell Point was not reporting. 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)

14.8 (13.6)

15.5 (14.7)

Rt. 31 Bridge

14.4 (13.8)

15.5 (17.4)

I-75 Bridge

14.6 (14.5)

18.3 (19.8)

Ft. Myers Yacht Basin

20.1 (21.4)

21.0 (21.9)

Cape Coral Bridge

26.9 (25.4)

27.9 (28.5)

Shell Point

NA (32.5)

NA (34.1)

 

Conditions are poor in the upper estuary due to high salinity.  Salinity at the Cape Coral Bridge is at the upper limit of the optimal range for the oyster, Crassostrea virginica.

 

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

 

Water Conservation Areas

 

Good dry-season recession rates (averaged over the last three weeks) continue to dominate the region.  WCA-3B was the only area where recession rates were Fair due to little change over time. Although recession rates were Good, the depths in the Everglades remain too deep for wading bird foraging.

This is normally not an issue at this time of year because foraging in support of nesting behavior does not usually begin until February.  Only the NW corner of WCA-3A had proper depths and recession rates to support wading birds.  However; birds are not using this area.  It may be that fish prey are not available (NOTE: Last year’s drought caused an 80% reduction in food, compared to the previous high-nesting-success year, for wading birds across the system).  Stages in WCA-1 are slightly below at Regulation, WCA-3 stages continue to be significantly below regulation, and WCA-2A remains above regulation.

 

Everglades National Park

 

Light rainfall over the holidays allowed Everglades National Park (ENP) wetland water levels to continue to decline.  In general, stations in the northern part of the system saw more substantial declines than those to the south.  Not surprisingly recession has been most dramatic at Taylor Sl. Bridge where water levels have dropped by 6” (0.5’) over the past 3 weeks.  Shark River Slough water level, as measured at P33, dropped by 2.2” over the past 3 weeks, and by nearly 0.75” over the past 7 days.  Overall water levels at these 2 stations (TSB & P33) are well below average for this time in the dry season, in part because neither area came close to their respective seasonal high water levels during the 2007 rainy season.  To the south water levels are slightly below average at Craighead Pond (station CP) & in the panhandle at EVER6.

 

Several of the marine monitoring stations have not transmitted data over the past week.  Overall, though, using what data are available (through USGS platforms & a few ENP stations that are online) it seems that FL Bay salinity as a whole remains fairly low for this time of year.  Salinity concentrations at Trout Ck. have generally remained in the mid-20s, while concentrations at Taylor River mouth have been slightly lower in the mid-teens.  In the Taylor River ponds salinity has generally remained low (near 1 psu).  In the north-central Bay, salinity in Terrapin Bay and McCormick Creek ranged between the teens & low-20s.  In central Florida Bay, Whipray Basin salinity continued to hold below 30 psu for the entire 3 week period, a good gauge of conditions across the area.  In the SRS outflow at Tarpon Bay, salinity increased from single digits to just above 10 psu as of 12/31.  The Bay continues to be well buffered in terms of salinity for the dry season.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast continued to decline this week – and are now below their historical average conditions for this time of year.  Water levels in the Lower East Coast are still slightly above their historical averages – although many wells recorded modest declines in the past week.  Water levels in the Upper East Coast continue to remain above their historic averages.  Surface and groundwater levels in Water Conservation Areas 1 and 2 are now near or 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 southern-most portion of Dade County are now below average historic conditions as a result of local rainfall.

 

Seven out of eleven water supply risk measures are in the “high” risk category - the projected Lake O Stage (SSM), the Palmer Index for Tributary Conditions, the CPC Precipitation Outlook, the LOK Seasonal Net Inflow Forecast and Lower East Coast Service Areas 1, 2 and 3.

 

Water Conservation Areas 1, 2A and 3A continue to be in the “low” risk category and the Multi-Seasonal Net Inflow Forecasts remain at “medium” risk this week.

 

Chlorides at the Olga WTP on the Caloosahatchee River are now at 178 ppm and the plant is operational.

 

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake O 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 Nina climactic conditions.

 

 

 

 

 

CC:   George Horne