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 29, 2008

 

SUBJECT:     Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Some active thunderstorm days ahead.  Decent moisture and favorable upper level winds between a high pressure area and an upper level low over the southeastern Bahamas should allow above average afternoon thunderstorm activity through Friday.  Steering winds will become more westerly and focus activity over the interior and east.  Thunderstorm coverage should drop down a bit Saturday as the upper level low passes to the south of the District.  The next ten days precipitation outlook is above average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 2.49 inches of rainfall to bring the 30 day total to 8.19 inches (122% of average), and the lower basin received 2.64 inches to bring the 30 day total to 10.46 inches (168% 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) are approaching or have reached the summer plateau of the regulation schedule.  Releases are being made from Lakes Hart (96 cfs), East Tohopekaliga (453 cfs), and Tohopekaliga (1413 cfs).

 

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

 

Flow is approximately 300 cfs at S65 and 2000 cfs at S65C.

 

The water level in the area of the restoration project decreases by 3.16 feet from 37.42 feet near the middle of the restored reach (station KRBN) to 34.26 feet at the downstream end (headwater stage at S-65C).  A portion of the floodplain within the restoration project is now inundated.

 

From 7/22/08 to 7/29/08 dissolved oxygen concentrations in the Kissimmee River ranged from 1.0 mg/L to 2.7 mg/L and averaged 1.8 mg/L.  Although concentrations have been below 2 mg/L for some time, no adverse effects have been reported.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.76’ NGVD, which is 0.37’ higher than a week ago, 1.18’ higher than a month ago, and 1.59’ higher than it was a year ago.  The current stage is 3.09’ below the historical average for this date, and 1.90’ below the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 6830 cfs, including substantial flows from the Kissimmee River (2685 cfs), S71 (2565 cfs), S72 (624 cfs), and the L8 at canal point (683 cfs), and lesser volumes through the S84 (684 cfs), S191 (320 cfs), and S154 (32 cfs).  Accurate outflows through S77 and S308 are not available.

 

St. Lucie Estuary

 

There were no releases through S-80 from C-44 over the past week.  An average discharge of 80 cfs through S-48 from C-23 and 234 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)

7.22 (6.48)

8.08 (7.46)

 

HR1 (N. Fork)

5.31 (2.58)

10.52 (9.51)

 

Roosevelt Bridge

9.70 (8.38)

12.23 (11.40)

8.0 – 25.0

A1A Bridge

18.91 (16.95)

25.61 (24.26)

20.0 – 31.0

 

Compared with salinities of the previous week, average salinity in the estuary increased about 0.5 to 2.7 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 1342 cfs occurred at S-79.  The concentration of chlorides at the Olga Plant was 62 ppm Monday, 7/28, up from 54 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 200cfs.  S78 has remained closed with no discharge throughout the month of July.

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

0.29 (0.43)

0.29 (0.40)

Rt. 31 Bridge

NR (NR)

NR (NR)

I-75 Bridge

0.41 (0.85)

0.41 (1.10)

Ft. Myers Yacht Basin

1.18 (3.15)

1.28 (3.55)

Cape Coral Bridge

6.81 (10.06)

8.62 (10.43)

Shell Point

20.22 (28.76)

22.29 (29.47)

 

Compared with salinities of the previous week, average salinity decreased throughout the estuary due to local runoff.  Average salinities dropped between 0.11 ppt and 8.54 ppt depending on location and depth.  The 30 day average surface salinity is decreasing and stands at 8 ppt.  Salinity conditions in the upper estuary east of Ft. Myers are good.  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.  Continued low salinity will result in poor conditions.

 

Background concentrations of Karenia brevis, the Florida red tide organism, were detected this week in a single water sample collected from Sarasota Bay.  All other water samples collected, both alongshore and offshore, between Pinellas and Monroe counties were free of any K. brevis.  A bloom of the dinoflagellate Pyrodinium bahamense is still present in Old Tampa Bay (Pinellas County).  No impacts have been reported.

 

Water Conservation Areas

 

Water levels continue to rise in the Everglades in response to rainfall.  Rehydration rates are good to fair throughout most of the conservation areas except for gauge 76 in WCA-3B, which reported a marked decrease (-0.35’).  Stages are currently above regulation levels in all three Water Conservation Areas.

 

Everglades National Park

 

Rainfall totals were light to moderate last week across Everglades National Park (ENP) and Florida Bay.  Weekly accumulations from the platforms for which we receive data ranged from trace amounts (< 0.1”) to 4.1” with the spatial distribution again skewed towards western areas of ENP.  The basin-wide spatially-averaged weekly totals were 1.97” in the ENP basin and 1.4” in the C-111 basin.

 

Stages in ENP wetlands showed mixed results, reflecting last week’s local rainfall patterns.  Water levels dropped 1” in the panhandle (station EVER6), and 2” at Taylor Slough Bridge.  After receiving over 4” of rain last week, water levels rose 1.3” last week at Shark River Slough (station P33) and about 1” at Craighead Pond.  However, stages remain unseasonably low in Taylor Slough.

 

Salinity trends across Florida Bay were stable or increased last week, with above average concentrations in many areas.  Creek salinity remains high, suggesting that the Everglades have been slow to rehydrate and to supply water southward to Florida Bay.  In addition, minimal rainfall across much of the Bay last week allowed salinity in the eastern Bay (Duck Key, L. Madeira Bay mouth) to rise slowly into the mid-30s.  Salinity in the Taylor River ponds remained in the lower 30s for the week; average concentrations should be approaching single digits by late July.  The Taylor River 30 day moving average salinity increased to 28.2 psu on Sunday.  Salinity rose above 40 psu in the shallow north central Bay areas of McCormick Creek and Terrapin Bay, while the central Bay Whipray Basin salinity remained in the mid 40s. In contrast, the upstream reaches of Shark River are responding to over 3.5” of rain and salinity continued to decline slowly towards freshwater concentrations.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin continued to improve this week in response to local rainfall.  Water levels in the Lower West Coast are mostly now at or above their historical averages, and there was continued rebound this week.  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 and continued to rise this past week.  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