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 22, 2008

 

SUBJECT:     Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Increased showers/storms today and tomorrow.  The last few days have seen well below average rains as tropical systems that developed around us spewed exhaust fumes over the peninsula.  These negative influences on our rains should begin to wane today.  Morning soundings show more moisture, cooler mid levels, and more favorable upper level winds for the seabreeze to work with.  Light steering winds make it more difficult to find a focus; but, areas north through east of of  Lake Okeechobee (Lake) should see the bulk of the late afternoon through mid evening storm activity.  Look for storms to increase in coverage tomorrow with a focus north through southwest of the Lake.  Then, showers, storms may decrease on Thursday and Friday afternoons before increasing again over the weekend.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 2.06 inches of rainfall to bring the 30 day total to 7.80 inches (113% of average), and the lower basin received 2.39 inches to bring the 30 day total to 10.07 inches (156% of average).

 

Water levels are rising 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.

 

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

 

Flow is approximately 200 cfs at S65 and 1800 cfs at S65C.

 

Water levels within the Kissimmee River Restoration Project area have been rising and falling in response to rainfall events.  The water level (headwater stage) at S-65C has been allowed to rise to 34 feet.

 

From 7/15/08 to 7/21/08 dissolved oxygen concentrations in the Kissimmee River ranged from 0.82 mg/L to 2.47 mg/L and averaged 1.5 mg/L.  Dissolved oxygen concentrations were lowest on Saturday 7/19/08 and have been increasing since then.


Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.39’ NGVD, which is 0.35’ higher than a week ago, 1.11’ higher than a month ago, and 1.34’ higher than it was a year ago.  The current stage is 3.38’ below the historical average for this date, and 2.17’ below the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 5229 cfs, including substantial flows from the Kissimmee River (2115 cfs), S71 (1973 cfs), S72 (181 cfs), and the L8 at canal point (645 cfs), and lesser volumes through the S84 (147 cfs), S191 (100 cfs), and S154 (68 cfs).   No outflows are reported and flows through S77 and S308 are not available.

 

Monthly phytoplankton monitoring was performed on July 17.  Six of nine sites had sufficient water for sampling.  Mean secchi depth was 0.59 m (compared to 0.43 m in June).  Chlorophyll and toxin data are not yet available, but bloom conditions were not observed at any of the stations.

 

The South American watergrass Luziola subintegra continues to pose an environmental threat in Fisheating Bay.  A dense monoculture of this species is estimated to cover 110 acres with considerable infiltration beyond this central stand.  Treatment by helicopter and boat is planned for this week using a mixture of the herbicides imazapyr and glyphosate, which has been the most effective combination used to date.

 

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 448 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)

6.48 (4.40)

7.46 (4.91)

 

HR1 (N. Fork)

2.58 (2.39)

9.51 (5.24)

 

Roosevelt Bridge

8.38 (7.24)

11.40 (8.79)

8.0 – 25.0

A1A Bridge

16.95 (15.00)

24.26 (21.68)

20.0 – 31.0

 

Compared with salinities of the previous week, average salinity in the estuary increased about 0.2 to 4.3 ppt.  Salinity conditions in the estuary are considered to be fair, based on the salinity preference of the oyster, Crassostrea virginica.

 

Caloosahatchee Estuary

 

An average weekly discharge of 2540 cfs occurred at S-79.  The concentration of chlorides at the Olga Plant was 54 ppm yesterday, down from 81 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).


 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

0.43 (3.60)

0.40 (3.84)

Rt. 31 Bridge

NR (NR)

NR (NR)

I-75 Bridge

0.85 (4.14)

1.10 (8.98)

Ft. Myers Yacht Basin

3.15 (10.24)

3.55 (15.06)

Cape Coral Bridge

10.06 (18.36)

10.43 (20.30)

Shell Point

20.84 (28.76)

22.57 (29.47)

 

Compared with salinities of the previous week, average salinity decreased throughout the estuary due to local runoff.  Average salinities dropped between 3 ppt and 11 ppt depending on location and depth.  Salinity conditions in the upper estuary east of Ft. Myers continue to improve this week.  Average salinity at the Ft. Myers surface sensor was 3.2 ppt.  The 30 day average surface salinity is decreasing and stands at 12.3 ppt.  Salinity at Cape Coral Bridge is below the preferred range for the oyster, Crassostrea virginica.  Conditions in the lower estuary between Cape Coral and Shell Point are poor considering the combined 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.  Discolored water has been observed near the mouth of the Caloosahatchee River (Lee County) and is due to a non-toxic phytoplankton bloom.

 

Water Conservation Areas

 

The wading bird foraging period ended everywhere in the EPA 2-3 weeks ago because all areas had significant stage increases and all are too deep for wading bird foraging.  This week, evapotranspiration was relatively low, but so was precipitation and therefore there were regions of the Everglades where re-hydration rates were too slow or even negative.  In general, water levels were stable and depths range from a low of 1.09 ft in WCA-3B to a high of 2.28 feet in the northeast reaches of WCA-3A and 2.73 ft in WCA-2B.

 

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

 

Everglades National Park

 

Stages were up across much of the Everglades National Park (ENP) wetlands, but by varying amounts depending on local rainfall.  Water level in the panhandle (station EVER6) remained nearly unchanged for the week.  Shark River Slough (station P33) saw increasing water level (up by 0.6”) last week.  Water levels were also up in Taylor Slough: Taylor Slough Bridge experienced a weekly increase of 5”, and to the southwest in Craighead Pond, water level was up by just over 1.5” from last week.

 

Salinity trends across Florida Bay were generally stable for a second week, though concentrations still remain above average in many areas.  Creek salinity is still high, suggesting that the Everglades have been slow to re-hydrate.  Salinity in the eastern Bay (Duck Key, L. Madeira Bay mouth) again measured in the mid-30s last week.   In the Taylor River ponds salinity increased last week, to above 30 psu by the weekend.  Despite this increase, the Taylor River (TR) 30 day moving average salinity dropped to 25.9 psu as of Sunday, 7/20 (down from last week’s reading of 26.9 psu).  Last week saw stable salinity (in the upper 30s) in the shallow northcentral Bay areas of McCormick Creek and Terrapin Bay, and in the central Bay Whipray Basin station (holding in the mid-40s).  In the upstream reaches of Shark River (Tarpon Bay platform, an area that was again the focus of the much rain for the week, ~ 3”), salinity continued a slow decline last week, approaching freshwater concentrations.

 

Wildlife:

 

Last week U.S. Fish and Wildlife biologists have found nests and recently hatched birds of the endangered Everglade snail kite in a small wetland in the Loxahatchee National Wildlife Refuge. An analysis is ongoing to look at WCA use by snail kites and will be reported as part of the District’s Annual Wading Bird Report.

 

For the last few weeks a bear (or two) appears to be ripping down scientific instruments on tree islands in the central Everglades. Florida Fish Wildlife Conservation Commission is expected to soon set up a camera to “capture” this large mammal activity.

 

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