MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       January 29, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

No Lake Okeechobee regulatory releases to the south or estuaries are recommended.

 

Background

 

Mainly warm and dry this week.  Deep layered high pressure dominates from the southern Gulf of Mexico through the Florida peninsula and up the Atlantic coast.  Elsewhere, a very active and progressive pattern exists over most of the US.  This general pattern should hold into next week, thereby allowing only the tail ends of weakening fronts to periodically drop into the peninsula before retreating northward.  This is not a favorable scenario for any significant rainfall, though some garbage showers should dampen a few lawns.  Next hope for significant rain is not obvious, but a front could push through in about 10 days.  The next ten days precipitation outlook is below average with moderate confidence.

 

Kissimmee Watershed

 

Over the last 7 days, the upper Kissimmee Basin received 1.15 inches of rainfall to bring the 30-day total to 3.08 inches, which was 132% of the long term average, and the lower basin received 0.26 inches to bring the 30-day total to 1.30 inches, which was 72% of average.  Continued rainfall caused water levels in the upper basin lakes to rise slightly (0.1-0.3 feet).  Water levels in the upper basin lakes remain below regulation schedules except for Lake Toho, which is slightly above regulation schedule.

 

Lake Kissimmee (S-65) continued discharging approximately 250 cfs to the Kissimmee River.  Releases from Lake Toho (S-61) began last week and have been increased to 700 cfs.  No other releases are being made in the upper basin.  Flow has been reestablished to the Kissimmee River for 188 days (S-65 re-opened on 07/18/07).

 

An update on dissolved oxygen concentrations in the river channel of the Kissimmee River is not available this week because of maintenance issues.

 

Anecdotal observations from last week included numbers of birds (wading, shore, and water) using the floodplain (Oak Creek marsh) within the Phase I area of the Kissimmee River Restoration Project.  Roseate spoonbills were also reported using the same marsh.


Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.06’ NGVD, which is 0.05’ lower than a week ago and 0.22’ lower than a month ago.  The current stage is 1.66’ lower than it was a year ago and 4.68’ below its historical average for this time of year.  Inflows from the Kissimmee River (S65E) continue at approximately 250 cfs.  No major outflows are reported.

 

Monthly phytoplankton monitoring was performed on January 23rd.  Six of the 9 monitoring stations had sufficient water to sample and no algal blooms were observed at any of these stations.  Average secchi depth declined to 0.29 m from 0.40 m in December, and average SD:TD declined to 0.23 from 0.30 in December.  A SD:TD ratio < 0.5 generally is not conducive to SAV growth.  These light conditions are normal for this time of year.

 

St. Lucie Estuary

 

There were no releases through S-80 from Lake Okeechobee or the C-44 Basin.  There was no discharge from S-49 on the C-24 Canal during the last week and average flow for the week from C-23 through S-97 was < 1.0 cfs.  The current weekly average salinities (in bold) at the four monitoring sites in the St. Lucie are given below in parts per thousand (ppt), along with the previous week’s (in parenthesis).

 

 

Weekly Average Salinity (ppt)

 

Sampling Site

Surface

Bottom

Envelope

Palm City Bridge (S. Fork)

11.2 (11.1)

 14.2 (13.5)

 

HR1 (N. Fork)

16.5 (15.4)

18.27 (16.8)

 

Roosevelt Bridge

19.2 (18.7)

20.2 (19.7)

8.0 – 25.0

A1A Bridge

27.3 (27.6)

28.7 (28.9)

20.0 – 31.0

 

Except at the A1A Bridge, average salinity increased slightly during the past week. Both the surface and bottom salinity are in the preferred range at the Roosevelt Bridge, and at the A1A Bridge.  The current surface salinity of 19.2 ppt at the Roosevelt Bridge is 8.8 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought (last week’s difference was 9.3 ppt). Based on the salinity tolerances of the oyster, Crassostrea virginica, salinity conditions in the estuary are good.

 

FWRI reports no Karenia brevis, the Florida red tide organism, in samples collected between Volusia and St. Lucie counties.

 

Caloosahatchee Estuary

 

Discharge for the week at S-79 averaged 367 cfs as a result of 3 days of flow with a peak of 966 cfs.  The 30-day average discharge from S-79 is 86 cfs.  The concentration of chlorides at the Olga Plant is 184 mg/l.  Weekly average salinities for specific sites are given below in parts per thousand (ppt).  Current weekly averages (in bold) may be compared to last week’s data (in parenthesis).


 



 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

16.9 (18.5)

17.8 (18.7)

Rt. 31 Bridge

17.7 (17.7)

19.5 (18.4)

I-75 Bridge

NA

20.5 (20.5)

Ft. Myers Yacht Basin

23.6 (22.7)

23.6 (22.9)

Cape Coral Bridge

25.3 (25.9)

30.3 (29.1)

Shell Point

33.8 (32.8)

35.3 (34.5)

 

Salinity declined only at the S-79 downstream recorder as a result of the S-79 releases. The salinity at all the other recorders located downstream of S-79 (except the Cape Coral surface sensor) either remained unchanged or salinity increased slightly.  The current surface salinity of 16.9 ppt at S-79 is 3.5 ppt below the maximum weekly average of 20.0 ppt achieved in May 2001 during the 2000 – 2001 drought.  Salinity at the Ft. Myers surface sensor remains above the 1-day MFL target (20 ppt).  Salinity at the Cape Coral Bridge surface recorder is at the upper limit of the optimal range for the oyster, Crassostrea virginica.  Salinity at the bottom sensor exceeds the preferred range.  Salinity at Shell Point is either near or is beginning to exceed the tolerance limits of oysters. Salinity downstream of Cape Coral is good for seagrass.

 

Based on submerged plants requirements, conditions in the upper estuary, east of Ft. Myers, are poor due to high salinity.  Based on the salinity tolerances of oysters, salinity conditions in the estuary downstream of the Cape Coral Bridge is fair.

 

FWRI reports that water samples collected along the shore between Pasco and Collier counties contained no Karenia brevis, the Florida red tide organism. Samples off shore had either no organisms or concentrations at background levels.

 

Water Conservation Areas

 

Good dry-season recession rates continue to dominate the region.  Like last week, only two regions had poor recession rates due to slight increases or no change.  They were the northern regions of WCA-1 and WCA-3B.  This should not set off any alarms and desires to reduce WCA-1 or WCA-3B water levels at this time because water levels are below average for this time of year and water conservation is needed.  Stages in WCA-1 are slightly below Regulation, WCA-2A remains above regulation, WCA-3 stages continue to be significantly below regulation, and there has been little change since last week.

 

Everglades National Park

 

Everglades National Park (ENP) wetland water levels showed mixed trends last week.  Water level at Taylor Slough Bridge remained unchanged from last week.  There was an increase in water levels in Shark River Slough (station P33, up by 0.4”) and in the panhandle (station EVER6, up by nearly 1” from last week as a result of high rainfall totals).  In South Taylor Slough, Craighead Pond water level declined by 0.6” over the 7 day period.

 

Salinity concentrations increased slightly or remained stable in Florida Bay last week.  Salinity held in the lower-20s at Trout Creek and in the mid-upper teens at the mouth of Taylor River.  The 30 day moving average concentration at Taylor River (used for to monitor exceedances to the FL Bay MFL rule) is still low (4 psu), which is good, but should be monitored closely due to the rate that it has been increasing over recent weeks.  The platform at Whipray Basin is again transmitting data, and recorded salinity near 30 psu over much of last week.  As a whole these salinity concentrations are near seasonal norms.

The exception to this trend is out west, in the Shark River Slough (SRS) outflow at Tarpon Bay, where salinity remains above its seasonal average, measuring 13.5 psu as of Sunday 1/27; this is not surprising given the low water levels in SRS.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast increased on average this week, but remain below their historical average conditions for this time of year.  Water levels in the Lower East Coast are still slightly above their historical averages, and most wells recorded modest increases in water levels due to local rainfall.  Water levels in the Upper East Coast continue to remain above their historic averages.  Surface and groundwater levels in Water Conservation Areas 1 and 2 are now near or slightly below their historic averages.  Water levels in WCA 3A continue to remain below their historic averages and were somewhat lower this week.  Water levels in the southern-most portion of Miami-Dade County are now below average historic conditions.

 

Seven out of eleven water supply risk measures are in the “high” risk category:  the projected Lake Okeechobee Stage (SSM), the Palmer Index for tributary conditions, the CPC precipitation outlook, the Lake Okeechobee seasonal net inflow forecast and Lower East Coast Service Areas 1, 2 and 3.  Water Conservation Areas 1, 2A and 3A continue to be in the “low” risk category and the Lake Okeechobee multi-seasonal net inflow forecasts remain at “medium” risk this week.

 

Chlorides at the Olga water treatment plant on the Caloosahatchee River are now at 184 ppm and the plant is operational.

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake Okeechobee stage remains in the Water Shortage Management zone and is unlikely to move back into Zone E in the next several months during the persistent La Niña climactic conditions.

 

 

 

 

 

 

 

 

 

 

CC:   George Horne