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 24, 2007

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

No regulatory releases to the south or estuaries are recommended.

 

Background

 

Above average rain days continue.  A deep layered trough extends from an anchoring low over West Virginia through the Gulf of Mexico.  The resultant upper level wind field is considerably more energetic than we normally see in late July.  So, a typically quiet/drier stage in the wet season has been displaced this year.  Look for heavy showers/storms to yield a general focus north through southeast of the Lake this afternoon/early evening.  Steering winds become light tomorrow, and this should translate into a focus of storms over the interior south.  Steering winds become more easterly on Thursday to probably provide some focus west of the Lake.  Rainfall may decrease to near average by Friday, but more changes on Saturday suggest an increase in rains again over the weekend.  The next ten days precipitation outlook is average with moderate confidence.

 

Kissimmee Watershed

 

The upper Kissimmee Basin received 3.14 inches of rainfall over the last 7 days to bring the total for the month to 7.74 inches (159% of average) and the lower basin received 1.93 inches to bring the total for the month to 8.17 inches (181% of average) (Daily Rainfall Report for 7/23/07).

 

Snail kites continue to nest on Lake Tohopekaliga.  No update from last week.

 

Flow has been reestablished to the Kissimmee River.  The river was without inflow from the upper basin for 252 days (gates at S-61 and S-65 were closed Wednesday 11/8/2006 and S-65 re-opened on 07/18/07).  Some movement of water began a few days earlier when the S-65A and S-65C structures were opened.

 

One week ago, the concentration of dissolved oxygen had declined to very low levels, but it has recovered fairly quickly as flow was reestablished.  Mean daily values have been near or above 2 mg/L for several days.

 

The algal bloom reported last week in Pool D section of the C-38 has disappeared with increased flow through the pool.

 

A small fish kill in Pool D was reported yesterday (Monday July 23, 2007).  Only tilapia was observed


Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.09’ NGVD today which is 0.01’ lower than it was a week ago and 0.17’ higher than it was a month ago. Surface inflows are 1696 cfs. and surface outflows are not reported due to missing S77 and S308 data.

 

This month’s water quality sampling was limited to 7 pelagic sites and the data are not yet available.

 

An algal bloom was reported on the north end of the lake between Taylor Creek and Nubbin Slough on Sunday.  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.  Average salinity was comparable to last week.  At the Roosevelt Bridge salinity averaged 14.0 ppt on the surface and 15.4 ppt on the bottom.  Corresponding values further downstream at the A1A Bridge are 23.5 ppt and 28.0 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 10 ppt on the surface and 14 ppt on the bottom.  In the South Fork, at the Palm City Bridge, corresponding values were 9.3 ppt and 11.0 ppt.  Salinity conditions are good.  Oyster survey results from FWRI indicate that average density of oysters in the St. Lucie increased from a mean density of 96.2 (+144.4) per meter square in the fall of 2006 to a mean density of 169.0 (+229.4) per meter square this past spring.

 

Caloosahatchee Estuary

 

Discharge at S-79 averaged 207 cfs last week.  Chloride concentration at the Olga Plant is presently 95 mg/l.  Average surface salinity did not change appreciably in the upper estuary, with surface salinity ranging from 5.8 ppt at S-79 to 13.3 ppt at Ft. Myers. Bottom salinities ranged from 6.3 ppt at S-79 to 17.1 ppt at Ft. Myers.  Salinity at Shell Point declined considerably averaging 30.5 ppt on the surface and 33.8 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 and Collier counties.

 

Water Conservation Areas

As would be expected with a balanced water budget, most gauges across the Everglades showed little change, and in fact, four of the 14 standard measuring sites showed a decline.  The only area with a significant stage increase was WCA-2B and this was due to high localized rain.  Average stage increase across the entire system for the week was only 0.04 ft. Depths, which averaged about 1 ft across the system, are relatively low for this time of year.  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

 

Water levels were unchanged from last week in the southern part of Taylor Slough, at Craighead Pond (CP).  Across all other areas of the Park, though, stages declined.  In SRS at P33, water level dropped slightly (by nearly 0.4”).  Water level in the Everglades National Park panhandle (at EVER6) saw a decline of 1.2”.  Once again Taylor Slough Bridge saw the largest weekly change, dropping by nearly 2.5” for the week.  The water budget for the southern Everglades was either balanced or negative for yet another week.

Despite lower water levels, salinity across FL Bay was generally stable.  Salinity at Trout Ck. remained below 5 psu for another week.  The platform at the mouth of Little Madeira Bay held for a second week near 20 psu.  Salinity in the TR ponds was very low all week at ~ 1 psu at Pond 5 and Argyle Hendry.  The 30 d moving average concentration at TR continues to slowly decline, remaining well below the 30 psu point (at 0.8 psu as of Sunday 7/22).  Salinity concentrations held steady again this week in the north-central Bay area of McCormick Ck. & Terrapin Bay at or near 20 psu.  In the central Bay, Whipray Basin salinity remained near 35 psu for yet another week.  To the north and west, Tarpon Bay (SRS outlflow) salinity stayed low at just below 2 psu as of Sunday, 7/22.

 

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.

 

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 are now at medium risk.  The CPC Precipitation Outlook remained at “low” risk this week, along with the LOK Seasonal Net Inflow forecasts.

 

Regarding “Utilities of Concern”, the water supply dept. has reduced the reporting frequency of most systems from weekly to monthly, in response to improved wet season conditions

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake O stage – at 9.07’ 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