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:            August 12, 2008

 

SUBJECT:     Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Below average rainfall expected.  Moisture has improved over central Florida this morning; but, instability is not impressive and westerly steering winds remain too strong to allow much seabreeze activity.  Therefore, look for generally below average shower/storm activity, but with some focus over the Upper Kissimmee and near the east coast each afternoon through Thursday.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.77 inches of rainfall to bring the 30 day total to 7.29 inches (108% of average), and the lower basin received 1.24 inches to bring the 30 day total to 9.43 inches (152% of average).

 

Water levels in all of the upper basin lakes are at or slightly below their regulation schedules.  Releases are being made from East Lake Tohopekaliga (290 cfs) and Lake Tohopekaliga (381 cfs).  Releases of 561 cfs are being made from Lake Kissimmee and discharge at S65C is approximately 1800 cfs.

 

Water depths on the floodplain within the restoration project range from approximately 0.4 to 2.3 feet and nearly all of the floodplain is inundated.

 

From 8/5/08 to 8/12/08 dissolved oxygen concentrations in the Kissimmee River ranged from 1.2 mg/L to 2.9 mg/L and averaged 1.9 mg/L.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 11.24’ NGVD, which is 0.22’ higher than a week ago, 1.12’ higher than a month ago, and 1.78’ higher than it was a year ago.  The current stage is 2.80’ below the historical average for this date, and 1.65’ below the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 4410, including continuous flows from the Kissimmee River (2042 cfs), S71 (1608 cfs), and S72 (201 cfs), and nighttime flows from the L8 at canal point (559 cfs).  No outflows are reported and no flows through S77 or S308 are reported.

 

The monthly submerged-aquatic-vegetation (SAV) survey was completed last week.  Thirty-five sites had sufficient water for sampling, and all but 1 site 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 20 of the 35 sites.

The vascular SAV species Vallisneria americana was present 8 of the 22 sites sampled near the northern and western shorelines but continues to be absent in the south (13 sites sampled).  For the first time in over a year, the southern naiad (Najas guadalupensis) was found in very low density in the northern region (Eagle Bay Island).

 

The comprehensive annual SAV mapping on Lake Okeechobee began last Tuesday and will continue thru this week.  With the help of staff from Watershed Management Department Staff, Everglades Division, Recover, Coastal Ecosystem Division, and the Chemistry Lab the entire littoral zone will be sampled to estimate the total acreage and spatial distribution of the dominant SAV species.  A preliminary map will be available at the end of the month.

 

St. Lucie Estuary

 

There were no releases through S-80 from C-44 over the past week.  An average discharge of 121 cfs through S-48 from C-23 and 220 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)

5.78 (5.08)

7.68 (6.01)

 

HR1 (N. Fork)

5.62 (4.60)

11.08 (9.66)

 

Roosevelt Bridge

9.03 (7.80)

12.57 (10.32)

8.0 – 25.0

A1A Bridge

18.88 (16.63)

24.87 (22.76)

20.0 – 31.0

 

Compared with salinities of the previous week, average salinity in the estuary increased about 0.7 to 2.8 ppt.  Three of four monitoring stations are reporting salinities within the preferred range.  Salinity conditions in the estuary are considered to be fair to good based on the salinity preference of the oyster, Crassostrea virginica, and location in the estuary.

 

Caloosahatchee Estuary

 

An average weekly discharge of 1003 cfs occurred at S-79.  The concentration of chlorides at the Olga Plant was 56 ppm yesterday, down from 64 ppm in the beginning of this reporting period.  The current weekly average salinities (in bold) at the six monitoring sites in the Caloosahatchee Estuary are given below in parts per thousand (ppt), along with the previous week’s (in parenthesis).

 

Based on the USGS flow meter located just below S-77 water is flowing back into the Lake at a rate of about 93 cfs.  S-78 has remained closed with no discharge since June 30th.

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

0.25 (0.29)

0.25 (0.29)

Rt. 31 Bridge

0.27 (0.30)

NR (NR)

I-75 Bridge

0.34 (0.40)

0.30 (0.39)

Ft. Myers Yacht Basin

1.07 (0.85)

1.49 (0.86)

Cape Coral Bridge

NR (7.78)

NR (9.54)

Shell Point

21.15 (22.88)

22.54 (24.41)

 

In the estuary, freshwater extends from S-79 downstream, at least to Ft. Myers. Salinity conditions in the upper estuary east of Ft. Myers are good (30 day average at Ft. Myers = 2 ppt).

Salinity at Cape Coral Bridge (based on other recorders) is close to last week’s averages and is below the preferred ranges for both oyster, Crassostrea virginica and seagrass, Halodule wrightii.  Conditions in the lower estuary between Cape Coral and Shell Point are fair-poor considering the combined salinity preference of oysters and seagrasses.  Salinity conditions in San Carlos Bay are good.

 

No Karenia brevis, the Florida red tide organism, was detected this week in water samples collected alongshore between Pinellas and Monroe counties.  Offshore samples, collected west of Sanibel Island, were also free of any K. brevis.

 

Water Conservation Areas

 

In spite of this net deficit, rehydration rates were good to fair over most of the Everglades (WCA-2A, WCA-2B, and WCA-3A).  Exceptions were in northern WCA-1 and the southern WCA-3B and Everglades National Park, which experienced net declines in stages.

 

Water depths at the gages are generally higher than depths a few weeks ago.  These depths range from 1.05’ in WCA-1 to 3.15’ in WCA-2B.  WCA-3A depths range from 1.6’ to 2.6’.

 

Stages are just below regulation in WCA-1, slightly above regulation in WCA-3A, but remain well above regulation in WCA-2A.

 

Everglades National Park

 

Rainfall totals were moderate last week across Everglades National Park (ENP) and Florida Bay.  Weekly accumulations from the marine and wetland platforms for which we receive data ranged from 0.5” to 2.5”.  Spatial distribution of precipitation was fairly even across the Bay and ENP.  The basin-wide spatially-averaged weekly RAINDAR total was 1.7” in both ENP and C-111 basins.

 

Stages in ENP wetlands increased last week.  The water level was up by 1.2” last week in Shark River Slough (station P33).  To the south, water level increased by approx. 2” and 3.25” in Craighead Pond (southern Taylor Slough) and the panhandle (station EVER6), respectively.  Data discrepancies from Taylor Slough Bridge must be resolved before trends can be determined for that area.

 

Salinity trends across Florida Bay were mixed last week, with concentrations remaining above normal in most areas.  In the eastern Bay (Duck Key, Little Madeira Bay mouth) salinity remained high, in mid- to upper 30s last week; this puts concentrations 10-15 psu above normal for this time of the wet season.  Salinity in the Taylor River ponds remained in the mid-30s last week; usually by August, concentrations here are in the single digits.  The Taylor River (TR) 30-day moving average salinity (used for tracking the Florida Bay MFL criterion) increased 2 psu from last week’s reading (30.9 psu), up to 32.9 psu as of Sunday.  Salinity decreased in the shallow north central Bay areas of McCormick Creek and Terrapin Bay, falling from the mid-40s down to the mid- to upper 30s.  Salinity was up slightly, however, at the central Bay Whipray Basin station, where it is now approaching 50 psu.  The only area close to seasonal concentrations was in the upstream reaches of Shark River (Tarpon Bay platform) where salinity is nearly fresh (< 1 psu).

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin are near average conditions for their respective periods of record, although Floridan aquifer wells showed  half to 1-foot declines over the past week.

Water levels in the Lower West Coast are mostly at or above their historical averages.  Water levels in the Lower East Coast are now near or slightly above historical averages.  Water levels in the Upper East Coast are significantly above their historic averages.  Surface and groundwater levels in Water Conservation Areas 1, 2 and 3 are now near their historic averages – most wells remained somewhat unchanged this week.

 

There was no change in the water supply risk indicators since last week.  Seven out of the eleven water supply risk indicator parameters are now in the “low” risk category, including the CPC Precipitation Outlook, Palmer Index for Tributary Conditions, the Lake Okeechobee Seasonal and Multi-seasonal Net Inflow Forecast, and Water Conservation Areas 1, 2A and 3A.

 

Three out the eleven water supply risk indicators are now in the “medium” risk category, including LEC Service Areas 1, 2 and 3.

 

Only one risk measure is now in the “high” risk category - the projected Lake Okeechobee Stage (Water Shortage Management Band)

 

 

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