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 5, 2008

 

SUBJECT:     Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Afternoon thunderstorm activity will continue.  Upper level wind flow has become less favorable for thunderstorm development than it was on Monday, August 4th so expect less shower coverage Tuesday and Wednesday with activity focused inland and west each day.  Moisture should increase from the east Thursday and bring morning showers east and afternoon thunderstorms mainly over the interior.  A cold front is forecast to move into Georgia Friday and then stall across Florida over the weekend.  This pattern should bring more westerly wind flow so expect afternoon thunderstorms activity to be focused over the interior and east Friday and Saturday.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 1.48 inches of rainfall to bring the 30 day total to 7.79 inches (116% of average), and the lower basin received 1.92 inches to bring the 30 day total to 8.77 inches (142% of average).  Water levels continue to rise in all of the upper basin lakes including Lake Kissimmee.  Some lakes (Lakes Hart & Mary Jane, East Lake Tohopekaliga, and Lake Tohopekaliga) have reached the summer plateau of the regulation schedule.  Releases are being made from Lakes Hart (273 cfs), East Tohopekaliga (554 cfs), and Tohopekaliga (1441 cfs).

 

In the upper basin, there are no known active snail kite nests at this time, but there are still young being fed around nest sites on Lake Toho, both at Big Grassy Island and around South Steer Beach.  "Independent" young continue to use the lakes for foraging (including young hatched outside KCOL, e.g., Lake Istokpoga) and appear to be moving freely within the system.

 

Flow is approximately 540 cfs at S65 and 1850 cfs at S65C.  The water level in the area of the restoration project decreases by 4.7 feet from 39.4 feet near the upstream end of the restored reach (station KRDR02) to 34.7 feet at the downstream end (headwater stage at S-65C).  Water depths on the floodplain within the restoration project range from approximately 0.5 to 2.4 feet. 

From 7/29/08 to 8/05/08 dissolved oxygen concentrations in the Kissimmee River ranged from 1.1 mg/L to 2.9 mg/L and averaged 2 mg/L, up slightly from the previous week.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.78’ NGVD, which is 0.02’ higher than a week ago, 0.82’ higher than a month ago, and 1.33’ higher than it was a year ago.  The current stage is 3.15’ below the historical average for this date, and 1.98’ below the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 4959 cfs, including substantial flows from the Kissimmee River (2432 cfs),

S71 (1591 cfs), S72 (194 cfs), and the L8 at canal point (617 cfs), and smaller flows through the S84 (52 cfs) and S191 (68 cfs).  No outflows are reported and flows through S77 and S308 are not available.

 

The Submerged Aquatic Vegetation (SAV) south transects were completed Monday, August 4th.  Transparencies were excellent at all sites (Secch disc visible on bottom) and we had one reading of >bottom at a site NW of Ritta Island which was 1.6 m in depth.

 

Chara was still sparse at most sites, though dense at Southbay-2.  It appears as though Chara is continuing to slowly increase in coverage and density.  Unfortunately, no Val or Potamogeton was found.  We also saw a nice largemouth bass in the area of Sbay-2; no other wildlife observations of note.

 

St. Lucie Estuary

 

There were no releases through S-80 from C-44 over the past week.  An average discharge of 250 cfs through S-48 from C-23 and 346 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)

5.08 (7.22)

6.01 (8.08)

 

HR1 (N. Fork)

4.60 (5.31)

9.66 (10.52)

 

Roosevelt Bridge

7.80 (9.70)

10.32 (12.23)

8.0 – 25.0

A1A Bridge

16.63 (18.91)

22.76 (25.61)

20.0 – 31.0

 

Compared with salinities of the previous week, average salinity in the estuary decreased about 0.9 to 2.9 ppt.  Two 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 1195 cfs occurred at S-79.  The concentration of chlorides at the Olga Plant was 64 ppm yesterday, up from 62 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 S77 water is flowing back into the Lake at a rate of about 200 cfs.  S78 has remained closed with no discharge from June 30th.

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

0.29 (0.29)

0.29 (0.29)

Rt. 31 Bridge

0.30 (NR)

0.25 (NR)

I-75 Bridge

0.40 (0.41)

0.39 (0.41)

Ft. Myers Yacht Basin

0.85 (1.18)

0.86 (1.28)

Cape Coral Bridge

7.78 (6.81)

9.54 (8.62)

Shell Point

22.88 (20.22)

24.41 (22.29)

 

Fresh water 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 is 5 ppt).  Salinity at Cape Coral Bridge is below the preferred range for the oyster, Crassostrea virginica and below the preferred range for seagrass, Halodule wrightii, upstream of Shell Point.  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 Collier counties.

 

Water Conservation Areas

 

This is the time of year that the Greater Everglades is expected to continuously rise at the rate of some 0.1 to 0.2 ft per week.  Since rainfall was not great enough to compensate for evapotranspiration everywhere, there were regions where stages decreased.  The WCA-1 decreased only slightly (-0.02 ft) and WCA-2A decreased significantly (-0.21 ft).  Healthy re-hydration appears to be happening in central WCA-3A and in NESRS.

 

Stages are at regulation in WCA-1 and WCA-3A, but remain well above regulation in Water Conservation Area 2A.

 

Everglades National Park

 

Spatial distribution of precipitation was fairly even across Florida Bay and Everglades National Park (ENP).  Stages in ENP wetlands showed mixed results last week.  Water levels dropped by nearly 2” last week in the panhandle (station EVER6), and by just over 3.25” at Taylor Slough Bridge.  Stages still remain well below normal for this time of year in Taylor Slough (both TSB & CP stations).  Both Shark River Slough (station P33) and Craighead Pond (southern Taylor Slough) saw increasing water level last week (up by 0.3” & 0.6”, respectively).

 

Salinity trends across Florida Bay were either stable or increasing last week, with concentrations holding above average in many areas.  Creek salinity remains high (upper 30s at United States Geological Survey (USGS) gauges Taylor River Mouth & Trout Creek), suggesting that the Everglades have been slow to re-hydrate and supply water southward to Florida Bay.  Salinity in the eastern Bay (Duck Key, L. Madeira Bay mouth) continued to creep up into the mid-upper 30s last week; this puts concentrations 10 -15 psu above the norm for this time of the wet season.  In the Taylor River ponds salinity rose into the mid-30s last week; on average, concentrations here should be in single digits by August.  The Taylor River (TR) 30 day moving average salinity (used for tracking the Florida Bay MFL criterion) increased from last week’s reading (28.2 psu), up to 30.9 psu as of Sunday, 8/3 (note this is not a separate exceedance from that reported in late May).  There was increasing salinity in the shallow northcentral Bay areas of McCormick Creek. And Terrapin Bay (into the mid-40s), and in the central Bay Whipray Basin station, where salinity rose into the upper-40s.  The one area close to seasonal concentrations was in the upstream reaches of Shark River (Tarpon Bay platform) where salinity held just above 1 psu.

 

The issue of high salinity across Florida Bay is of concern, particularly given low creek inflows this year.  The wet season flows this year have been well below average:  cumulative flows for June and July were negative when on average these two months should provide approx. 54,000 acre-ft from the five creeks that are monitored by USGS (W. Highway + Trout + Mud + Taylor + McCormick).  By the looks of the creek data for June and July (WY09), plus sustained high salinity in the Bay, the creeks are not yet delivering Everglades water southward to the Bay.  For most months with positive flow, Trout is close to 50% of the flow into the Bay.

The minimum flow to Florida Bay, cited in the MFL Rule, is 105,000 acre-feet per year (365 day running total) through the five creeks gauged by USGS.  Over the 1997-2007 period of record the average is 260,000 acre-feet per year.  However, there has been extremely low (or no) fresh water flow to Florida Bay since the beginning of the dry season last fall and, over the past week, the creeks’ running total flow dropped below 105,000 acre-feet.  This corresponds to high salinity conditions at the Florida Bay MFL indicator site (above the 30 psu threshold that defines an MFL exceedance).

 

This is something that will need to be monitored closely.

 

Water Supply

 

There was very little change in groundwater levels across most of the area of the District during the past week.  Water levels in the upper and lower Kissimmee Basin are near there all-time average conditions for their respective periods of record.  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 still 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