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:                 August 28, 2007

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

 

Recommendation

 

No regulatory releases to the south or estuaries are recommended.

 

Background

 

Afternoon thunderstorms.  Steering winds should focus daily activity over the interior and west today through Wednesday.  An upper level trough should increase overall coverage Thursday and Friday, particularly north.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

The upper Kissimmee Basin received 1.40 inches of rainfall over the last 7 days to bring the 30-day total to 4.91 inches (71% of average) and the lower basin received 0.52 inches to bring the total for the month to 4.13 inches (66% of average) (Daily Rainfall Report for 08/27/07).

 

Stages in most of the upper basin lakes have been stable over the last seven days and are below schedule.  The stage in Lake Toho has increased slightly in part because of increased inflow from Shingle Creek.

 

Snail kites continue to nest on Lake Tohopekaliga.  The most recent survey found nests with eggs, nestlings and recent fledglings (USFWS August 8, 2007).  We can expect nesting to continue for at least another month.

 

Flow has been reestablished to the Kissimmee River for 41 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 today which 0.01’ higher that it was a week ago and 0.40’ higher than it was a month ago.  Surface inflows are 530 cfs, down from 881 cfs last week, and surface outflows are not reported due to missing S77 and S308 data.

 

This month 21 of the 27 water quality sampling sites had sufficient water for sampling but only TSS results are available. TSS values averaged 8 mg/L.  In April 07, the last time the same 21 sites were sampled, mean TSS was 60 mg/L.  As reported earlier in the month, this improved water clarity is associated with a substantial expansion of SAV cover in the nearshore zone of 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)

2.7

3.4

 

HR1 (N. Fork)

3.9

7.4

 

Roosevelt Bridge

7.8

8.9

8.0 – 25.0

A1A Bridge

15.5

24.3

20.0 – 31.0

 

Average weekly salinity in the North and South Forks declined slightly since the last report.  Local freshwater inflow continues to maintain surface salinity at both the Roosevelt Bridge and A1A Bridge below the preferred ranges.  Therefore, salinity conditions in the estuary are fair.

 

Caloosahatchee Estuary

 

During the past week, discharge at S-79 occurred on two days and averaged 50 cfs for the week.  Chloride concentration at the Olga Plant is presently 82 mg/l.  In general, average salinity at the monitoring sites in the Caloosahatchee Estuary increased 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)

8.0

9.0

Rt. 31 Bridge

NA

10.2

I-75 Bridge

7.7

11.6

Ft. Myers Yacht Basin

14.0 *

NA

Cape Coral Bridge

19.1

20.7

Shell Point

30.5

33.0

* based on two-day average.

 

Since surface salinity exceeds 10 ppt at the Ft. Myers Yacht Basin, salinity conditions in the upper estuary remain poor.  In the lower estuary and San Carlos Bay salinity condition are good.

 

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.  Discolored water due to a bloom of the cyanobacteria Trichodesmium remains possible along portions of the southwest Florida coast.

 

Water Conservation Areas

 

The conservation area gauges reported rising water stages in the northern conservation areas but falling in the more southerly ends of WCA-3 and in Everglades National Park (ENP).  Everglades ecosystems are habituated to rising water levels in the wet season.  At this time of year, falling stages in the Everglades equate to “Poor” conditions.  Like last week, stages in WCA-1 are below regulation but still in Zone A2, stages in WCA-2 are above regulation, and stages in WCA-3 are below regulation.  Water depths remain between 1-1.5 feet in the conservation areas, but were lower (below 0.7 foot) in the northern ENP area.

A large fire (“Mack’s Fish Camp South” fire) of 23,096 acres burned in WCA-3B, merging with another 3,500 acre fire from the week before.  It was triggered by a lightning strike on Aug. 17 and was declared under control August 26.  Predicted rainfall from the tropical wave failed to materialize and so the fire continued unchecked.

 

Everglades National Park

 

Water levels decreased at all Everglades National Park (ENP) platforms last week, likely in part to the light rainfall pattern and high evapotranspiration rates.  At Taylor Slough Bridge water level plunged by nearly 5.5” to reach just below ground surface.  In the panhandle region (EVER 6), water level declined by 2”.  Stage at Craighead Pond (CP) and to the north in Shark River Slough (P33) dropped by approximately 1” over the 7 day period.

 

Salinity showed mixed trends across Florida Bay last week but remains seasonably low.  Salinity at Trout Creek was flashy throughout the week, measuring between 4 - 15 psu.  The platform at the mouth of Little Madeira Bay saw salinity holding below 20 psu for another week.  Salinity in the Taylor River ponds remained very low all week (~ 1 psu at Pond 5 and Argyle Hendry).  Salinity readings in the north-central Bay areas of Terrapin Bay and McCormick Creek remained in the mid to low 20s last week.  In the central Bay, Whipray Basin salinity remained near 40 psu for another week.  To the north and west, Tarpon Bay (SRS outflow) salinity was low, holding below 2 psu for another week.

 

Water Supply

 

Water levels in the Lower West Coast (LWC) continue to remain near low levels for their periods of record, and water levels generally decreased in the LWC over the past week.  Water levels declined slightly in the coastal areas of the Upper East Coast and Lower East Coast over the past week, but they remain above their historical averages.  Surface and groundwater levels decreased on average over the past week in the Kissimmee Basin.

 

There were no changes in the Water Supply Risk Evaluation metrics between last week and this week.  Five 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, 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.  The LOK Multi-Seasonal Net Inflow Forecast remains at 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