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 8, 2008

 

SUBJECT:         Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Afternoon showers and storms mainly west through north of Lake Okeechobee; then well below average rains Wednesday through the end of the week.  Mid level high pressure is building westward into south Florida this morning.  Satellite pictures show significantly drier air with some embedded African dust extending from the Bahamas back to hurricane Bertha.  Southeast winds will bring this air into southern and eastern sections of the District today.  Western and northern sections should still see a decent crop of storms this afternoon.  Then, stable and drier air will envelop the entire District by this evening leading to several days of well below average rainfall.  Rains won’t likely increase to near normal until at least Sunday or early next week.  The next ten days precipitation outlook is below average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.92 inches of rainfall to bring the 30 day total to 7.68 inches (106% of average), and the lower basin received 3.20 inches to bring the 30 day total to 10.34 inches (151% of average).

 

Decreased rainfall over the upper basin relative to the previous two weeks slowed or ended the rise in water levels that had been occurring in most of the lakes.  Releases were made temporally at S-62 (Lakes Hart and Mary Jane), S-59 (East Lake Toho), and S-61 (Lake Toho) to slow the rate of rise as water level approached the regulation schedule.  The water released from these lakes was held in Lake Kissimmee, where it had little impact on the water level.  All lakes remain below regulation schedule.

 

In the upper basin, snail kites continue to nest on East Lake Toho, Lake Toho, and Lake Kissimmee.

 

Flow has been reestablished to the Kissimmee River for 357 days (S-65 re-opened on 07/18/07).  Flow is approximately 200 cfs at S65.  River water levels within the Kissimmee River Restoration Project area have been rising and falling in response to rainfall events.  Last week’s rainfall caused water levels to increase by >1.5 feet in the upper reach of the restoration project.

 

Dissolved oxygen concentrations in the river channel of the Kissimmee River temporally fell below thresholds of concern.  Concentrations ranged from 0.13 mg/L to 4.4 mg/L and averaged of 2.9 mg/L.


Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.02’ NGVD, which is 0.37’ higher than a week ago, 0.58’ higher than a month ago, and 0.99’ higher than it was a year ago.  The current stage is 3.61’ below the historical average for this date, and 2.38’ below the simulated historical average for the current regulation schedule (LORS2008).

Total reported inflows are 4105, with most flow coming from the Kissimmee River (1541 cfs), S71 (1237 cfs), S72 (586 cfs), and the L8 at canal point (609 cfs).  No outflows are reported and no flows through S77 or S308 are reported.

 

June water-quality monitoring results are now available.  Thirteen of the 25 monitoring stations had sufficient water for sampling.  Total phosphorous averaged 80 ppb lakewide (compared to 185 ppb in May) and 25 ppb at nearshore stations (compared to 52 ppb in May).  Total suspended solids (TSS) averaged 22 ppm lakewide (compared to 68 ppm in May) and 4 ppm at nearshore stations (compared to 14 ppm in May).

 

The monthly submerged-aquatic-vegetation (SAV) survey was completed yesterday.  Twenty seven sites had sufficient water for sampling, and all sites had water clarity conducive to plant growth (secchi depth > 50% of total depth).  The macroalga Chara remains the dominant SAV species and was found at 12 of the 27 sites.  The vascular SAV species Vallisneria americana was present 7 of the 16 sites sampled near the northern and western shorelines but continues to be absent in the south (11 sites sampled).  For the first time in over a year, the southern naiad (Najas guadalupensis) was found in very low density in the southern region (west side of Ritta Island).

 

St. Lucie Estuary

 

There were no releases through S-80 from C-44 over the past week.  An average discharge of 348 cfs through S-48 from C-23 and 292.4 cfs through S-49 from C-24 occurred over the past week.  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)

6.91 (13.15)

8.06 (15.43)

 

HR1 (N. Fork)

7.47 (14.72)

11.67 (17.95)

 

Roosevelt Bridge

11.39 (18.30)

12.45 (19.15)

8.0 – 25.0

A1A Bridge

19.55 (24.68)

20.12 (NA)

20.0 – 31.0

 

Compared with salinities of the previous week, average salinity decreased throughout the estuary due to local runoff.  Salinity declined between 5 ppt and 7 ppt depending on location and depth.  Salinity at Roosevelt Bridge is within the preferred range.  Salinity at A1A Bridge is at the lower limit of the preferred range.  Salinity conditions in the estuary are considered to be good, based on the salinity preference of the oyster, Crassostrea virginica.  The current surface salinity of 11 ppt at the Roosevelt Bridge is 17 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

 

Caloosahatchee Estuary

 

An average weekly discharge of 688 cfs occurred at S-79.  The concentration of chlorides at the Olga Plant was 102 ppm yesterday, down from 130 ppm in the beginning of this reporting period.  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)

5.86 (7.79)

6.24 (8.15)

Rt. 31 Bridge

5.91 (7.96)

8.63 (11.74)

I-75 Bridge

6.42 (10.08)

12.03 (15.71)

Ft. Myers Yacht Basin

4.56 (18.31)

17.18 (21.32)

Cape Coral Bridge

23.93 (26.68)

24.45 (26.99)

Shell Point

33.11 (33.03)

33.36 (33.30)

 

Compared to last week, average salinities dropped between 2 ppt and 4 ppt except at Shell Point where salinity stayed the same.  Average salinity at the Ft. Myers surface sensor was 15 ppt, which is 5 ppt below the 1-day MFL criterion of 20 ppt.  The current surface salinity of 6 ppt at S-79 is 14 ppt below the maximum weekly average of 20.0 ppt achieved in May 2001 during the 2000 – 2001 drought.  Salinity at Cape Coral Bridge is within the preferred range for the oyster, Crassostrea virginica.  Salinity conditions in the upper estuary east of Ft. Myers continues to improve this week.  Conditions in the lower estuary downstream of Cape Coral are good considering the combine salinity preference of oysters and seagrasses.

 

No Karenia brevis, the Florida red tide organism, was detected this week in water samples collected alongshore between Pinellas and Collier counties.

 

Water Conservation Areas

 

Last week we saw a reprieve for the wading birds and their ability to feeding their fledglings because good recession rates occurred in quite a few locations.  However, this week, the foraging period has officially ended everywhere in the EPA, because all areas had significant stage increases and all are too deep for wading bird foraging.  Water levels increased by an amazing 0.67 ft (8 inches) in WCA-2A.  The smallest increase in stage was in WCA-1 (0.06 ft or ¾ inch). Depths range from a low of 1.13 feet in WCA-3B to a high of 2.05 ft in the southern region of WCA-3A (the L-67 c and d levees work to maintain this hydrologic disparity).

 

Stages are currently above regulation in all three Water Conservation Areas.

 

Everglades National Park

 

Spatially variable rainfall again produced mixed trends for Everglades National Park (ENP) wetland water levels.  Shark River Slough (station P33) water level was nearly unchanged from last week (despite having receiving approx. 1.5” of rain for the week).  Water level dropped by nearly 2” (falling just beneath ground surface) for the week at Taylor Slough Bridge, an area where water levels have experienced rapid increases over recent weeks.  To the south, water level increased by 1.2” and 1.6” at Craighead Pond and in the panhandle (station EVER6), respectively.

 

Salinity trends across Florida Bay were also mixed last week.  Only the eastern-most USGS & ENP platforms at Highway Creek (HC) and Long Sound recorded declining salinity over the past week, with HC reaching single digits as of Sunday, 7/6.  Salinity in the eastern Bay proper (e.g., Duck Key, L. Madeira Bay mouth), held in the mid-30s for yet another week.  The Taylor River (TR) 30day moving average salinity (used for tracking the Florida Bay MFL criterion) dropped to 29.1 psu as of Sunday, 7/6 (down a bit from last week’s reading of 31.7 psu); Friday (7/4) was the first time in 41 days this value has been below the 30 psu threshold.  Salinity in the central Bay station at Whipray Basin remained stable in the mid 40s.  In the upstream reaches of Shark River (Tarpon Bay platform, an area that received 4.5” of rain last week), salinity continued to decline last week, reaching seasonal oligohaline (< 5 psu) concentrations.

 

Water Supply

 

Did not Report Week of July 8, 2008

 

LORS2008 (Lake Okeechobee Regulation Schedule)

 

The current Lake Okeechobee stage remains in the Water Shortage Management zone and is unlikely to move back into the Operational Band in the next several months.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CC:   George Horne