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:                 September 11, 2007

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

No regulatory releases to the south or estuaries are recommended.

 

Background

 

Daily afternoon thunderstorms decreasing by the end of the week.  A trough which had been over the District the past two days has lifted north of the District so expect shower coverage to drop down some today.  An upper level low located near Tampa should still tap decent moisture over the area and generate afternoon thunderstorms focused over the interior today and Tuesday.  Southeasterly winds will then focus scattered afternoon thunderstorms over the interior and west Thursday and Friday as drier air spreads over the area.  A cold front is forecast to move into north Florida and weaken over the weekend.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

The upper Kissimmee Basin received 0.85 inches of rainfall over the last 7 days to bring the 30-day total to 3.52 inches (52% of average) and the lower basin received 1.21 inches to bring the 30-day total to 4.36 inches (70% of average) (Daily Rainfall Report for 09/10/07).  Stages in most of the upper basin lakes have been stable over the last seven days.  Stage at S65C headwaters has increased 0.5 feet in response to Kissimmee Division request to raise the stage to 35 feet over the next several weeks.

 

Snail kites continue to nest on Lake Tohopekaliga.

 

Flow has been reestablished to the Kissimmee River for 55 days (S-65 re-opened on 07/18/07).  Discharge at S-65 continues at approximately 500 cfs.  For the last week, the concentration of dissolved oxygen in the river channel has remained above thresholds of concern with mean daily values above 5 mg/L for the previous week

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.57’ NGVD, which is 0.02’ higher than a week ago and 0.11’ higher than a month ago.  The current stage is 3.73’ lower than it was a year ago and approximately 4’ below its historical average for this time of year.  Reported surface inflows are 1039 cfs compared with 1392 cfs last week.  These values do not include gravity inflows through the S77 (76 cfs) and S308 (not reported) structures.  No surface outflows are reported.

 

Monthly algal bloom monitoring was conducted on the 22nd of August.  Four of the 10 monitoring sites were dry.  An algal bloom was present at 1 of remaining 6 survey locations.  Algal toxins were not detected.

The September submerged-aquatic-vegetation (SAV) survey documented SAV at 80% of the sites sampled.  Several other sites sampled in previous surveys were dry.  Water clarity was excellent at all sites.  Results show that SAV continues to recover following the hurricanes of 2004 and 2005, which removed most of the SAV from the lake.

 

St. Lucie Estuary

 

No releases occurred at S-80 over the past week.  Weekly average salinities at the four monitoring sites in the St. Lucie are given below in parts per thousand (ppt).

 

 

Weekly Average Salinity (ppt)

 

Sampling Site

Surface

Bottom

Envelope

Palm City Bridge (S. Fork)

7.8

9.6

 

HR1 (N. Fork)

11.7

14.2

 

Roosevelt Bridge

16.4

17.2

8.0 – 25.0

A1A Bridge

25.2

28.9

20.0 – 31.0

 

Average weekly salinity in the estuary increased since the last report.  Local freshwater inflow continues to maintain surface salinity at both the Roosevelt Bridge and A1A Bridge within the preferred ranges.  Therefore, salinity conditions in the estuary are good.

 

Caloosahatchee Estuary

 

During the past week, discharge at S-79 averaged 164 cfs.  Chloride concentration at the Olga Plant is presently 77 mg/l.  Average salinity at the monitoring sites in the upper Caloosahatchee Estuary decreased slightly over the past week.  Data for specific sites are given below in parts per thousand (ppt).

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

6.6

7.1

Rt. 31 Bridge

NA

7.7

I-75 Bridge

5.8

9.8

Ft. Myers Yacht Basin

8.0*

NA

Cape Coral Bridge

19.6

21.0

Shell Point

30.2

33.8

* based on two-day average.

 

Salinity in the upper estuary remains high for this time of year.  The 30-day average surface salinity at Ft. Myers is 11.4 ppt and decreasing.  Conditions in the upper estuary are fair.  Downstream of the Cape Coral Bridge salinity conditions are good.

 

During the last sampling trip to the Caloosahatchee at the end of August, a plankton bloom was noted upstream of S-79.  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.


Water Conservation Areas

 

On average, water levels are where they were last week.  WCA-3A and 3B continue to have POOR inundation rates.  A maximum stage decrease of -0.10 ft for the Everglades occurred in northern WCA-3A (Gage 62).  Depths are below 1 ft for much of WCA-3 and NE Shark River Slough. Stages in WCA-1 are below regulation but still in Zone A2.  Stages in WCA-2 and stages in WCA-3 are below regulation

 

Everglades National Park

 

Rainfall was heavier last week than we have seen of late across Everglades National Park (ENP) and Florida Bay. Precipitation totals at wetland & marine platforms ranged from 0.8 – 3.7” over the 7 d period.  As a result, Taylor Slough Bridge saw increasing water levels (up by nearly 4” for the 7 day period).  In the panhandle region (EVER 6) & to the west at Craighead Pond (CP), water levels were up by just over 3” as of Sunday (9/9).  Rainfall came at a good time to halt recent unseasonable water level recessions in these wetland areas.

 

Salinity showed mixed trends across FL Bay last week.  Salinity at Trout Ck. was flashy again last week, ranging from 10 – 25 psu.  Salinity in the Taylor ponds remained very low for much of the week (~ 1 psu at Argyle Hendry, TR), with the exception of a flow reversal that pushed Bay water up Taylor River and increased salinity to 10 – 15 psu in the latter part of the week at Pond 5 (just downstream from station TR).  Salinity readings in the north-central Bay areas of Terrapin Bay and McCormick Creek have continued to increase in recent weeks.  This week’s strong southerly winds pushed Bay water into shallow Terrapin Bay and drove salinity up into the mid-30s by the weekend.  In the central Bay, Whipray Basin salinity continued a slow tick upwards, increasing to 41 psu by the weekend.  To the north and west, Tarpon Bay (SRS outlflow) salinity remained low, holding near 2 psu for another week.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast (LWC) continue to remain near low levels for their periods of record – although there was some recovery in shallow wells in the LWC this week as a result of local rainfall.  Water levels declined slightly in the coastal areas of the Upper East Coast and Lower East Coast over the past week, but they remain near or above their historical averages.  Surface and groundwater levels in the Water Conservation Areas are near the historic lowest levels recorded for this time of year also.

 

Six out of eleven water supply risk measures are in the “high” risk category this week including the projected Lake O Stage (SSM), the Palm Index for Tributary Conditions, the LOK Multi-Seasonal Net Inflow Forecast and Lower East Coast Service Areas 1, 2 and 3.

 

Water Conservation Areas 1, 2A continue to be in the low risk category.  Water Conservation Area 3A changed from “low” to “medium” risk this week.  The CPC Precipitation Outlook remains at “low” risk this week, along with the LOK Seasonal Net Inflow forecast.

 

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake O stage – at 9.57’ today - remains in the Water Shortage Management zone and is unlikely to move back into Zone E in the next two months.

 

CC:   George Horne