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 21, 2007

 

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

No regulatory releases to the south or estuaries are recommended.

 

Background

 

Increased rains beginning late tomorrow.  Hurricane Dean has moved inland over the Yucatan and weakened.  So, its influence on our weather will finally decrease.  Look for moisture and instability to increase slowly through tomorrow before widespread showers/storms return to the entire District on Thursday with the passage of a tropical wave.  Then, barring more nearby tropical development, a more typical pattern of rainfall should persist the last week of the month.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

The upper Kissimmee Basin received 0.45 inches of rainfall over the last 7 days to bring the 30-day total to 6.59 inches (96% of average) and the lower basin received 1.06 inches to bring the total for the month to 6.25 inches (100% of average) (Daily Rainfall Report for 08/21/07).

 

Stages in most of the upper basin lakes have been stable over the last seven days and are at schedule.  The stage in Lake Kissimmee had risen to within 0.5 ft of the regulation schedule for this time of year (summer pool) but has started to decline.

 

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 another month.

 

Flow has been reestablished to the Kissimmee River for 34 days (S-65 re-opened on 07/18/07).  Discharge at S-65 continues at approximately 450 cfs.

 

For the last week, the concentration of dissolved oxygen in the river channel has remained above thresholds of concern with mean daily values increasing from 2.32 mg/L on August 14 to 5.65 mg/L on August 19.

 

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.56’ NGVD today which 0.10’ higher that it was a week ago and 0.51’ higher than it was a month ago.  Surface inflows are 881 cfs. 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; however the results are not yet available.

 

Approximately 8,000 acres of torpedograss from the Indian Prairie marsh south to the Moore Haven marsh are currently being treated at a rate of approximately 670 acres per day.  The intent is to treat at least 12,000 acres this year while lake levels are low.

 

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)

2.9

3.9

 

HR1 (N. Fork)

4.2

9.00

 

Roosevelt Bridge

7.6

8.5

8.0 – 25.0

A1A Bridge

15.0

20.1

20.0 – 31.0

 

Local freshwater inflow has caused surface salinity at both the Roosevelt Bridge and A1A Bridge to fall below the preferred range.  Therefore, salinity conditions in the estuary are fair.

 

Caloosahatchee Estuary

 

Discharge at S-79 averaged 246 cfs over the past week.  Chloride concentration at the Olga Plant is presently 83 mg/l.  Weekly average salinity at the monitoring sites in the Caloosahatchee Estuary are given below in parts per thousand (ppt).

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

5.9

6.0

Rt. 31 Bridge

NA

6.3

I-75 Bridge

5.2

8.8

Ft. Myers Yacht Basin

12.6 *

NA

Cape Coral Bridge

18.4

19.1

Shell Point

29.7**

32.1**

 

* average of past two days; ** average of past 4 days; NA= not available

 

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.

 

Water Conservation Areas

Changes in water depths for the Conservation Areas varied.  All stations in WCA-1 reported decreases up to -0.1 foot from the week before, and stages in the Everglades National Park and parts of WCA-3A also decreased.  Stages rose, as preferred, in WCA-2B and 3B, as well as in central WCA-3.  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.  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 also below regulation.

 

 

Everglades National Park

 

Everglades National Park (ENP) wetland stations have reported no rain or stage data since last Thursday, so stage data are missing for last week; nearby USGS data were used to update conditions in these areas.  ENP wetland water levels displayed mixed trends for the week.  Water levels dropped by nearly 1” in southern Taylor Slough (at E146), while they were up 1” to the east in the panhandle/C111 region, probably because of local rainfall differences.  In Shark River Slough, water levels increased by nearly 0.5” (stations NE4 and NE5).

 

Salinity continued to remain seasonably low across Florida Bay.  Salinity both at Trout Creek and the mouth of Taylor River was flashy again last week, jumping between 5–15 psu, which is normal for this time of year.  Salinity concentrations in the Taylor River ponds remained very low, close to 1 psu.  At the mouth of Little Madeira Bay, salinity remained near last week’s concentration of just below 20 psu.  In the north-central Bay, McCormick Creek salinity also remained close to last week’s concentrations of the mid-20s.  Whipray Basin salinity continued to increase somewhat, probably a result of low local rainfall and high evaporation, but remained near seasonable levels.  Salinity to the west in the Shark River Slough outflow of Tarpon Bay stayed low, between 1–2 psu for the 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.

 

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 9.56’ 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