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 10, 2007

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

 

Recommendation

 

No regulatory releases to the south or estuaries are recommended.

 

Background

 

Below average rains expected this week.  We have probably moved out of the first phase of the wet season and into the "doldrums".  This second phase is usually characterized by more easterly flow that has a tendency to focus sea-breeze storms west through north of the Lake.  In general, rainfall decreases about 20% from the first phase; but, this is mainly because the next six weeks usually lacks big rain events.  The third and final phase begins around August 20th.  Ultimately, most wet seasons are remembered by how this highly variable, two month phase plays out.

 

This week:  Look for afternoon showers/storms to decrease in coverage through Wednesday before increasing some each day into the weekend.  The next ten days precipitation outlook is below average with moderate confidence.

 

Kissimmee Watershed

 

The upper Kissimmee Basin received 2.66 inches of rainfall over the last 7 days to bring the 30-day total to 9.82 inches (107% of average) and the lower basin received 4.01 inches to bring the 30-day total to 9.59 inches (110% of average) (Daily Rainfall Report for 7/09/07).

 

Large numbers of snail kites, including fledglings from this year, are still associated with Lake Tohopekaliga and Lake Kissimmee.  Only Lake Tohopekaliga has active nests, including some recent ones.

 

Recent rainfall has caused water levels in the upper basin to rise by variable amounts.  With rainfall and increased inflow from Shingle Creek, the water levels in Lake Toho have risen to the regulation schedule.  Small releases of approximately 100 cfs are being made from Lake Tohopekaliga to Lakes Cypress, Hatchineha, and Kissimmee.

 

The Kissimmee River has lacked inflow from the upper basin for 244 days (gates at S-61 and S-65 were closed Wednesday 11/8/2006).

 

Concentration of dissolved oxygen in the Phase I restored river channel continues to fall but remains above thresholds of concern with mean daily values exceeding 2.70 mg/L for the last seven days.


Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 9.10’ NGVD today which is 0.28’ higher than it was a week ago and 0.12’ higher than it was a month ago. Surface inflows are 1537 cfs. and surface outflows are not reported due to missing S77 and S308 data.

 

The monthly SAV sampling is complete and 15 of the 23 sites visited had plants.  Last month 9 of the 20 sites visited had plants. A total of 43 sites were dry which is similar to last month.  Moderate to dense beds of Chara were observed off of the northwest tip of Ritta Island and east of Kreamer Island in Pelican Bay. Sparse to moderate Chara was also observed along the western shore from Clewiston to the Cochran’s Pass area.  Very sparse Chara is beginning to appear along the northern shore in the Tin House Cove area and west of King’s Bar.  Light penetration is excellent with Secchi Depth to Total Depth ratios of 1.0 at all sites indicating most of the light is reaching the bottom in the near shore areas.

 

In the past 2 weeks, approximately 5000 acres of the previously burned marsh areas in Indian Prairie and north of the Moore Haven canal were treated for torpedo grass regrowth.

 

The in-lake muck removal efforts are complete and approximately 1.9 million cubic yards of phosphorus-rich muck were removed from the lake bottom.

 

St. Lucie Estuary

 

No releases occurred at S-80 over the past week.  At the Roosevelt Bridge salinity averaged 8.31 ppt on the surface and 15.4 ppt on the bottom for the week.  Corresponding values further downstream at the A1A Bridge are 22.96 ppt and 26.08 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).

 

Caloosahatchee Estuary

 

Discharge occurred at S-79 over the past week (weekly average 526 cfs).  Weekly average surface salinity ranged from 7.91 ppt at S-79 to 17.43 ppt at Ft. Myers. Bottom salinities ranged from 12.85 ppt at S-79 to 18.23 ppt at Ft. Myers.  Salinity at Shell Point averaged 35.74 ppt on the surface and 36.91 ppt on the bottom.   Although salinity has decreased in the upper estuary, it is still higher than what is desirable.  In the lower estuary and San Carlos Bay high salinities are good for seagrass and fair for oysters.

 

Water Conservation Areas

On average, the stage increased by 0.05 ft more than last week for most of the Everglades. Stage increases ranged from 0.09 ft (WCA-3A) to 0.28 ft in WCA-2A.  WCA-2B continues to be something of an enigma.  Last week the 99-gage decreased while the marsh increased.  This week, the 99-gage in WCA-2B increased by an incredible 2.79 ft while the marsh hardly increased.

 

Sections of WCA-3A continue to experience declining water levels, but not as bad as last week. The northeastern section of 3A has been below ground for the last three weeks.  

 

WCA-1 and 3 are approaching Regulation and WCA-2A is above Regulation.


Everglades National Park

 

Northwestern & southeastern areas of ENP receiving more rainfall than other areas.  Unfortunately, the dataset for the ENP wetland stations was incomplete for the week (due to some issues w/ lightening tripping up communication from the platforms).  A summary through Friday, 7/6, indicates that water levels were generally up 0.5” to 1.3”.  Only Taylor Slough Bridge saw a decline in water level of nearly 1” for the period Mon – Fri. of last week.  The panhandle water levels (measured @ EVER6) increased by nearly 0.5” : SRS at P33 water level jumped by 1.3” over the 5 d period. In general, and despite the drought, stages are higher in the ENP than they were this time last year.

Salinity continued to drop or remain low across FL Bay last week.  Salinity at Trout Ck. dropped to below 5 psu last week.  Salinity in the TR ponds was very low all week (~ 3 psu @ Pond 5 & nearly fresh up at Argyle Hendry).  The 30 d moving average concentration at TR continues to decline, remaining well below the 30 psu point (at 2.7 psu as of Sunday, 7/8).  In the central Bay, Whipray Basin salinity held near 35 psu for yet another week.  To the north and west, Tarpon Bay (SRS outflow) salinity remained low at near 2 psu as of Sunday, 7/8.

 

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 and 2A are now in the low risk category.  The Lake Okeechobee Multi-seasonal Net Inflow Forecast, the Palmer Index for Tributary Conditions and Water Conservation Area 3A stage are now at medium risk.  The CPC Precipitation Outlook remained at “low” risk this week, along with the LOK Seasonal Net Inflow forecasts.

 

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.  There was no significant news to report on “Utilities of Concern” monitored by the Water Supply Department this week.

 

 

 

 

CC:   George Horne