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:                 July 31, 2007

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

No regulatory releases to the south or estuaries are recommended.

 

Background

 

Moderate thunderstorm coverage today and Wednesday, then drier through the weekend.  An upper level trough continues to bring some favorable upper level wind-flow today which is tapping ample moisture over the area.  Scattered showers and thunderstorms have developed again along the west coast and this activity should shift eastward and increase in coverage through the day.  A weak surface low is forecast to develop in the northeast Gulf of Mexico along a weakening cold front.  This low should bring westerly to southerly steering winds over the area and focus thunderstorm activity north and northeast Wednesday.  Drier air moving in from the southeast will then decrease thunderstorm coverage Thursday through the weekend.  The next ten days precipitation outlook is near average with moderate confidence.

 

Kissimmee Watershed

 

The upper Kissimmee Basin received 1.27 inches of rainfall over the last 7 days to bring the 30-day total to 9.08 inches (136% of average) and the lower basin received 1.30 inches to bring the total for the month to 9.61 inches (156% of average) (Daily Rainfall Report for 7/30/07).

 

Stages in the upper basin lakes are starting to rise, especially in Lake Kissimmee.

 

Fish and Wildlife Conservation Commission reports germination and growth of native submersed aquatic vegetation, such as eelgrass (Valisneria) and Illinois pondweed (Potomegeton illinoensis), in some areas of Lake Tohopekaliga and in Lakes Kissimmee, Hatchineha and Cypress.

 

Snail kites continue to nest on Lake Tohopekaliga.  No update from two weeks ago.

 

Flow has been reestablished to the Kissimmee River for 13 days (S-65 re-opened on 07/18/07).  Discharge at S-65 has increased to approximately 500 cfs.  Discharge through the restored reach of the river is approximately 1000 cfs with the additional 500 cfs coming from tributary inflows and basin runoff.

 

The concentration of dissolved oxygen has fallen to very low levels.  The low oxygen concentrations are probably related to the large contribution of basin runoff to discharge through the restored reach.  Both river channel sites report values of 0.5 mg/L or less of dissolved oxygen for the last week.  At these low levels, a fish kill is possible.  Low oxygen concentrations two weeks ago may have allowed fish to acclimate to low oxygen concentrations.  Current water levels should allow fish access to the floodplain where higher oxygen concentrations have been measured in previous years.

 

A small algal bloom was noted by the boat ramp at S65 between the SR 60 bridge and the navigation lock and probably consists of algae just piled up in that corner due to wind action.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.19’ NGVD today which is 0.10’ higher than it was a week ago and 0.33’ higher than it was a month ago. Surface inflows are 3249 cfs. and surface outflows are not reported due to missing S77 and S308 data.

 

This month’s water quality sampling was limited to 4 pelagic sites and 3 near shore sites.  At the 4 pelagic sites Total Phosphorus concentrations averaged 142 ppb and Total Suspended Solids averaged 51 mg L-1.  These levels are lower than last months values of 216 ppb Total Phosphorus and 82 mg L-1 Total Suspended Solids at these 4 pelagic sites.  The 3 near shore sites were not sampled last month due to low lake levels so no values are available for comparison.

 

The monthly algal bloom monitoring was conducted on the 16th of this month and at that time no algal blooms were reported and toxin levels were below the analytical level of detection (0.2 ug L-1).  However, an algal bloom was observed on the north end of the lake extending approximately 2 miles northwest and 2 miles southeast of S191 last week.  Rainfall induced nutrient rich inflows might stimulate more algal blooms, especially near major lake inflow sites.

 

St. Lucie Estuary

 

No releases occurred at S-80 over the past week.  At the Roosevelt Bridge salinity averaged 13.0 ppt on the surface and 13.8 ppt on the bottom.  Corresponding values further downstream at the A1A Bridge are 20.1 ppt and 25.3 ppt.  Salinities at both sites are within the preferred range (8-25 ppt for the Roosevelt Bridge and 20-31 ppt for the A1A Bridge).  In the North Fork at the Harbor Ridge station, salinity averaged 7.9 ppt on the surface and 13.9 ppt on the bottom.  In the South Fork, at the Palm City Bridge, corresponding values were 6.8 ppt and 8.8 ppt.  Salinity conditions are good.

 

Caloosahatchee Estuary

 

The estimated weekly average discharge at S-79 was about 370 cfs.  Chloride concentration at the Olga Plant is presently 88 mg/l.  Average surface salinity did not change appreciably in the upper estuary, with surface salinity ranging from 6.3 ppt at S-79 to 13.2 ppt at Ft. Myers. Bottom salinities ranged from 6.6 ppt at S-79 to 16.0 ppt at Ft. Myers.  Salinity at Shell Point declined again this week averaging 28.6 ppt on the surface and 33.4 ppt on the bottom.  Salinity remains high in the upper estuary.  In the lower estuary and San Carlos Bay salinity conditions 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 Collier counties.  Discolored water due to a bloom of the non-toxic cyanobacteria, Trichodesmium, remains possible in portions of Charlotte, Lee (including San Carlos Bay) and Collier counties.


 

Water Conservation Areas

Unlike last week, when rainfall barely matched evaporation and some regions receded, this week surplus rainfall translated into stage increases everywhere in the Everglades and in some regions they where relatively substantial, i.e., over 0.30 ft/week.  Marsh depths now range between 0.57 ft and 1.6 ft. (Note: Gage 99 is not considered a marsh gauge.), and continued increases are seen a good thing for the environment.  In terms of the Regulations Schedules; WCA-1 is at Regulation, WCA-2A is above Regulation, and WCA-3A is below regulation.

 

Everglades National Park

 

Rainfall was spatially variable across ENP and FL Bay last week (weekly precipitation totals ranged from 0.25 – 4”.  Platform communication issues prevented us from providing a full week’s worth of data for the ENP wetlands.  Data through Thursday, 7/26, suggest that water levels are quickly increasing as water flows southward.  Over the 4 day period for which we have data, some of the stage increases were substantial (~ 3” Taylor Slough. Bridge & at P33 in Shark River Slough).  Salinity remained seasonably low and stable across FL Bay last week.  Salinity at Trout Creek ranged from < 5 psu to 15 - 20 psu (likely as a result of a temporary wind-driven reversal).  Salinity at the mouth of Taylor River was flashy, but generally remained below 10 psu.  Salinity concentrations in the Taylor River ponds held very low all week (close to 1 psu at Pond 5 & at Argyle Hendry).  In the north-central Bay areas of McCormick Ck. and Terrapin Bay salinity remained near seasonal concentrations of 20 psu.  In the central Bay, Whipray Basin salinity held steady near 35 psu for yet another week.  To the north and west, Tarpon Bay (SRS outflow) salinity was low, holding between 1 – 2 psu last week.

 

Water Supply

 

Water levels in the Lower West Coast continue to remain near low levels for their periods of record, although rebound continues to occur in the coastal areas of the Upper and Lower East Coasts and Water Conservation Area 1 as a result of local rainfall.  The USGS has initiated reporting of water levels in several wells in the Kissimmee River Basin - levels in many wells appear to be very low (within the lowest 10% of recorded values) compared with the historic periods of record.

 

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

 

Water Conservation Areas 1, 2A and 3A are now in the low risk category.  The Palmer Index for Tributary Conditions is now at medium risk.  The CPC Precipitation Outlook remained at “low” risk this week, along with the LOK Seasonal Net Inflow forecast.

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake O stage – at 9.19’ 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