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 18, 2007

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

 

Recommendation

 

No regulatory releases to the south or estuaries are recommended.

 

Background

 

Scattered mainly afternoon thunderstorm activity.  Good moisture and favorable upper level wind flow should help generate an above average thunderstorm day today.  Morning shower activity along the east coast will shift to the interior and west this afternoon.  As drier air moves into the area, daily coverage of thunderstorm activity will drop down Wednesday through Friday but remain focused over the interior and west.  Activity will then focus over the interior Saturday. The next ten days precipitation outlook is near average with moderate confidence.

 

Kissimmee Watershed

 

The upper Kissimmee Basin received 1.26 inches of rainfall over the last 7 days to bring the total for the month to 4.69 inches (139% of average) and the lower basin received 1.88 inches to bring the total for the month to 6.24 inches (203% of average) (Daily Rainfall Report for 7/16/07).

 

Last Friday (July 13), USFWS provided a snail kite update for Toho - 4 new nests were found.  Currently, snail kites have 20 active nests on the lake, including several that contain eggs.  This indicates that the snail kite nesting season may be extended this year.

 

In the upper basin, lake stages have remained fairly stable over the last seven days.  Small releases of approximately 150 cfs continue to be made from Lake Tohopekaliga to keep the lake at regulation schedule.

 

The Kissimmee River has lacked inflow from the upper basin for 251 days (gates at S-61 and S-65 were closed Wednesday 11/8/2006).

 

Water levels in Pool C have risen approximately 0.25 ft from rainfall and runoff.  Concentration of dissolved oxygen in the Phase I restored river channel has fallen below thresholds of concern.  One station (KRBN) has fallen to 1.56 mg/L in the last few days and the other station (PC62) has been measuring values much less than 1 mg/L for the last seven days.

 

On Wednesday July 11th, measurements of dissolved oxygen in the restored river channel indicate a strong gradient of decreasing concentration from surface to the bottom at two locations (PC62 and KRBN).  At PC62, DO concentration was 3 mg/L at 0.5 meters and 0.61 near the bottom of the channel.  At KRBN, DO concentration was 6 mg/L at 0.5 m and 0.75 mg/L near the bottom.

 

Algal bloom reported in Pool D section of the C-38 but not in Pool C (Monday July 16).

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.10’ NGVD today which is the same as it was a week ago and 0.18’ higher than it was a month ago. Surface inflows are 831 cfs. and surface outflows are not reported due to missing S77 and S308 data.

 

The monthly bloom sampling is complete and no blooms were reported at any of the 6 sites visited. Light penetration was good with Secchi Depth to Total Depth ratios greater than 0.5 at all but one of the sites. Toxin data are not yet available.

 

St. Lucie Estuary

 

No releases occurred at S-80 over the past week.  Salinity continued to decline due to local runoff.  At the Roosevelt Bridge salinity averaged 14.2 ppt on the surface and 15.0 ppt on the bottom for the week.  Corresponding values further downstream at the A1A Bridge are 22.5 ppt and 27.6 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).  Salinity conditions are good.

 

Caloosahatchee Estuary

 

Discharge averaged 161 cfs last week.  Chloride concentration at the Olga Plant is presently 91 mg/l.  Weekly average surface salinity continued to decline and ranged from 5.3 ppt at S-79 to 14.6 ppt at Ft. Myers. Bottom salinities ranged from 7.8 ppt at S-79 to 15.3 ppt at Ft. Myers.  Salinity at Shell Point averaged 35.5 ppt on the surface and 36.9 ppt on the bottom.  Salinity remains high in the upper estuary.  In the lower estuary and San Carlos Bay high salinities are good for seagrass and fair for oysters.

 

There have been reports of anoxic bottom water around the Route 31 Bridge.  District staff completed a survey on July 10, 2007 and detected hypoxic bottom water (dissolved oxygen concentration < 2.00 mg/l) extending from just downstream of S-79 to Marker 27 near Beautiful Island, a distance of about 14 kilometers.

 

FWRI reports that no Karenia brevis, the Florida red tide organism, was detected alongshore this week in samples collected between Pinellas and Monroe counties.

 

Water Conservation Areas

With the summer rainfall, average stages increased by 0.09 ft this week.  Stages increased up to 0.48’ in the more northern areas, but they receded in part of WCA-3A, 3B, and northeast Shark River Slough. WCA-2B is finally acting as one would expect—both gauges reported an increase, consistent with reported marsh water levels.

 

All stations in the WCA’s are now reporting surface water ranging from 0.55’ to 1.48’.  WCA-1 is at regulation, WCA-2 is above, and WCA-3 is below Regulation.

 

Everglades National Park

 

Rainfall was patchy across Everglades National Park (ENP) and Florida Bay.  Rainfall was generally heavier in ENP than in Florida Bay, particularly in northwestern ENP; wetland stations received 1.4” - 2” while the Bay stations received generally < 1”.  The weekly spatially averaged ENP basin-wide accumulation was identical to last week’s at 1.8”.

 

Water levels were either stationary or retrograde last week across the ENP wetlands.  Water levels remained virtually unchanged in Shark River Slough at P33 but were lower to the south.  This week, stages declined by 1.4” in the ENP panhandle and by 0.8” to the west at Craighead Pond (CP).  Taylor Slough Bridge dropped by over 2.5” despite receiving nearly 2” of rainfall for the week.  These data suggest that evapotranspiration either equaled or exceeded other freshwater inputs (flow and rain) in the southern Everglades.

 

Salinity continued decreased or remained low across Florida Bay.  Salinity at Trout Creek remained below 5 psu for a second consecutive week and dropped steadily to around 20 psu at the mouth of Little Madeira Bay.  Salinity was flashy at the mouth of Taylor River (TR), but continued a general decline to between 5 - 12 psu (down from a maximum of 15 psu last week).  Salinity in the Taylor River ponds was very low all week, ~ 2 psu at Pond 5 and nearly fresh at Argyle Hendry.  The 30 d moving average concentration at Taylor River continued to decline slightly, remaining well below the 30 psu point (at 1.4 psu as of Sunday 7/15).  Salinity should remain low in the ponds for the remainder of the wet season.  Salinity concentrations remained steady again near 20 psu this week in the north-central Bay area of McCormick Creek and near 35 psu at Whipray Basin.  To the north and west, Tarpon Bay (SRS outflow) salinity was low, below 2 psu on Sunday.

 

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.

 

Four out of eleven water supply risk measures are in the “high” risk category this week.  The projected Lake O Stage (SSM), 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 Lake Okeechobee Multi-seasonal Net Inflow Forecast and 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.  A study of drought-related surcharges implemented or proposed by the LEC utilities also has been initiated

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake O stage – at 9.10’ 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