MEMORANDUM

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       October 2, 2007

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

No regulatory releases to the south or estuaries are recommended.

 

Background

 

Rains should decrease but remain above average today, decrease further tomorrow before increasing again the latter part of the week and into the weekend.  A complex trough an attendant upper low has moved westward into the eastern Gulf of Mexico.  An associated surface low is attempting to develop over the Lower Keys.  This regression has changed our wind field from strong, convergent northeasterly to moderate southeasterly.  As a result, look for showers/storms to decrease and switch focus from the east coast to interior and northern areas today and tomorrow.  Rains should increase by the end of the week as a moisture rich tropical feature moves through the northwest Caribbean.  The next ten days precipitation outlook is above average with moderate confidence.

 

Kissimmee Watershed

 

The upper Kissimmee Basin received 0.37 inches of rainfall over the last 7 days to bring the September total to 4.62 inches (75% of average) and the lower basin received 0.64 inches to bring the September total to 5.76 inches (96% of average).  So far, the wet season has produced 24.91 inches (90% of normal for this portion of the wet season) for the upper basin and 24.84 inches (96% of normal for the lower basin (Daily Rainfall Report for 10/01/07).  Stages in most of the upper basin lakes have been stable over the last seven days.

 

As lake stage went above schedule, water has been released from Lake Tohopekaliga (S-61) and is being held in Lakes Cypress, Hatchineha, and Kissimmee.

 

Flow has been reestablished to the Kissimmee River for 75 days (S-65 re-opened on 07/18/07).  Discharge at S-65 continues at approximately 500 cfs.  Because of problems with sensors, there is no update on dissolved oxygen.

 

The most recent wading bird survey found the number of foraging wading birds, primarily white ibis, had increased over the last two months but was much lower than has been typical for September since Phase I of Kissimmee River Restoration Project was completed.  Waterfowl abundance has also increased with the arrival of small groups of migrant blue-winged teal.


Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.85’ NGVD, which is 0.07’ higher than a week ago and 0.33’ higher than a month ago.  The current stage is 3.52’ lower than it was a year ago and remains approximately 5’ below its historical average for this time of year.  Total surface inflows are not reported due to missing data from the S65E (Kissimmee River) and Fisheating Creek.  Using reported discharges from the S65C to estimate contributions from the Kissimmee River, total inflows are approximately 900 cfs.  No surface outflows are reported.

 

During September, 20 of 27 water quality sampling sites had sufficient water for sampling.  Data from this sampling event should be available this week.  The October submerged-aquatic-vegetation (SAV) monitoring is being conducted this week.

 

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)

1.5

1.6

 

HR1 (N. Fork)

1.3

3.2

 

Roosevelt Bridge

3.6

3.8

8.0 – 25.0

A1A Bridge

12.8

20.0

20.0 – 31.0

 

Rainfall and associated local runoff lowered average salinity throughout the estuary last week.  Average salinity for the week was at the lower limit or below the preferred at the Roosevelt and A1A Bridges.  Based on the salinity tolerances of the oyster, Crassostrea virginica, salinity conditions in the estuary are poor at the Roosevelt Bridge and fair at the A1A Bridge.

 

Caloosahatchee Estuary

 

Discharge data for the full week were not available at the time of writing.  Between 9/25 and 9/30/2007 discharge at S-79 averaged 586 cfs.  Average salinity decreased throughout the estuary last week.  Data for specific sites are given below in parts per thousand (ppt).  The Ft. Myers site is being repaired.

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

3.3

3.4

Rt. 31 Bridge

3.7

3.7

I-75 Bridge

3.2

4.7

Ft. Myers Yacht Basin

NA

NA

Cape Coral Bridge

14.5

17.4

Shell Point

24.4

26.3

 

Salinity conditions throughout the system are good.

 

FWRI reports that water samples collected this week detected Karenia brevis, the Florida red tide organism, at very low concentrations at southern Sanibel Island (Lee County) and at background concentrations near Clam Pass (Collier County).  Background concentrations of K. brevis were also found in an offshore sample collected 1.5 miles south of Sanibel Island.  All other samples collected between Pinellas and Collier counties contained no K. brevis.


Water Conservation Areas

 

Water levels have increased significantly for a second week, and all gauges recorded a good wet season inundation (i.e., re-hydration) rate.  A maximum inundation of 0.62 ft per week was recorded in WCA-2A.  The lowest inundation (0.07 ft per week) was recorded at gauge 62 (NW WCA-3A).  Inundation rates were directly related to rainfall patterns.  As one would expect, water levels are approaching more realistic wet season values of 2 ft to 3 ft.  However, there are still many regions of the Everglades below average.  Stages in WCA-1 are approaching regulation but are still in Zone A2. Stages in WCA-2A are now well above regulation and stages in WCA-3 are still below regulation.

 

Everglades National Park

 

Wetland stations received between 1.1 – 5.1” of rain.  The weekly RAINDAR Everglades National Park (ENP) spatially averaged basin-wide accumulation was just over 4” last week; though even more impressive was the total of 10.5” for the C-111 basin just to east.  ENP wetland water levels increased as a result of this rainfall and flow from upstream.  Stations in the south all saw impressive increases in stage last week: 7.2” at Taylor Sl. Bridge, 5.3” in the ENP panhandle (EVER6), & 4.3” at Craighead Pond.  Shark River Slough (P33), which received less rain, saw only a slight increase in water level (0.4”) for the 7 d period.  Also, as a result of this rain, the seven gates on the S-197 were opened at noon on October 1 sending freshwater to Barnes Sound.  Four of these gates are expected to be closed by 5 pm October 2.

 

Salinity showed mixed trends across FL Bay last week in conjunction with the spatial distribution of rainfall.  Strong discharge moving out of the creeks toward Florida Bay allowed salinity to drop into single digits at both Trout Ck. & Taylor River mouth platforms by the weekend.  Salinity in the TR ponds remained at or below 1 psu all week.  Salinity concentrations in the central Bay saw the most substantial weekly change: areas of McCormick Ck. and Terrapin Bay where salinity was just over 30 psu early last week fell into the teens by the weekend.  Whipray Basin salinity dropped from 42 psu to 37 psu.  As an interesting contrast, Tarpon Bay (SRS outflow), where rainfall was much lighter, salinity increased from 5 last week to 10 psu this week.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast continue to remain near low levels for their periods of record – although there was some continued recovery in shallow wells in the LWC and UEC this week as a result of local rainfall.  Water levels also rebounded in the coastal areas of Lower East Coast over the past week, and they are now near or slightly above their historical averages.  Surface and groundwater levels in Water Conservation Areas 1 and 2 are now near the historic averages.  Water levels in WCA 3A are still somewhat below their historic averages.  Water levels in the southern-most portion of Dade County continued to rebound, as a result of local rainfall.

 

Five out of eleven water supply risk measures are in the “high” risk category this week, an improvement from last week.  The projected Lake O Stage (SSM), the Palmer Index for Tributary Conditions and Lower East Coast Service Areas 1, 2 and 3 are still in the high risk category.

 

Water Conservation Areas 1 and 2A continue to be in the “low” risk category and Water Conservation Area 3A is now at “medium” risk.  The CPC Precipitation Outlook remains at “low” risk this week, and the LOK Seasonal and Multi-Seasonal Net Inflow forecasts are now at “medium” risk.

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake O stage – at 9.85’ today - remains in the Water Shortage Management zone and is unlikely to move back into Zone E in the next two months.  The water level in Lake Istokpoga has declined to below the floor of the schedule, and the SFWMD is initiating the process of requesting a deviation from the current regulation schedule.  Some of the water users in that basin have initiated requests to install “emergency supply wells” to supplement their expected demands over the next year.

 

CC:   George Horne