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:            September 9, 2008

 

SUBJECT:     Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

Inflows from the tributary basins have continued to taper off but remain in the very wet tributary hydrologic conditions.   Stages in Lake Okeechobee (Lake) have risen to within one foot of the intermediate band, which calls for discharges of up to 4000 cfs at S-77 and up to 1800 cfs at S-80.  The United States Army Corps of Engineers (USACE) initiated releases on September 4th.  The District scientist have conducted site visits to monitoring stations within Lake Okeechobee and have indicated that the very rapid rise in Lake stages continue to impact the Lake ecology.

 

Background

 

Moderate rainfall mainly south through Wednesday.  Hurricane Ike is moving westward through western Cuba.  This track will take Ike into the southeast Gulf Tuesday afternoon.  Look for outer bands to wrap northward and focus rains south of Lake Okeechobee through Tuesday evening.  Steering flow becomes more southeasterly Wednesday and southerly on Thursday as Ike moves away and high pressure attempts to build in.  Look for rains to decrease to near normal by Thursday and below normal on Friday.  The next ten days precipitation outlook is near average with low confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received approximately 0.08 inches of rainfall to bring the 30 day total to 10.09 inches (149% of average).  The lower basin received approximately 0.82 inches to bring the 30 day total to 12.55 inches (202% of average).(Daily Rainfall Report 9/9/08).

 

Water levels in all of the upper basin lakes are very close to their regulation schedules.  Releases are being made from Lake Myrtle (106 cfs), Lake Hart (122 cfs), East Lake Tohopekaliga (695 cfs), Lake Tohopekaliga (1,952 cfs), The Alligator Chain (200 cfs) and Lake Gentry (237 cfs).  All lake releases are slightly lower than last week.

 

Discharge from Lake Kissimmee decreased from > 7,000 cfs to 4,111 cfs and discharge at S65C is down from over 10,000 cfs to 6,559 cfs.

 

Water depths on the floodplain within the restoration project have decreased by 0.5 – 1.0 ft over the last week.  However, some areas are still as deep as 6.8 feet. From 9/02/08 to 9/9/08 dissolved oxygen concentrations in the Kissimmee River ranged from 0.2 mg/L to 2.5 mg/L and averaged 1.1 mg/L.  Dissolved Oxygen concentrations are still below levels of concern at certain times.  However, concentrations have increased from last week.


Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 15.10’ NGVD, which is 0.50’ higher than a week ago, 3.99’ higher than a month ago, and 5.51’ higher than it was a year ago.  The current stage is 0.66’ above the historical average for this date, and 1.70’ above the simulated historical average for the current regulation schedule (LORS2008).  Total reported inflows are 10644 cfs, with the greatest contributions from the Kissimmee River (6830 cfs), S71 (1569 cfs), S72 (577 cfs), S191 (288 cfs), Fisheating Creek (739 cfs).  Back-pumping from the EAA is occurring through S2 and S4 at a combined 139 cfs.  Outflows from the lake include 4672 cfs through the S77 and 1725 cfs through the S308.

 

St. Lucie Estuary

 

During the last week, an average discharge of 1912 cfs occurred at S-80 from C-44 and 879 cfs at S308.  An average discharge of 666 cfs through S-48 from C-23 and 818 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)

0.22 (0.17)

0.22 (0.17)

 

HR1 (N. Fork)

0.29 (0.15)

0.47 (0.17)

 

Roosevelt Bridge

0.92 (0.20)

1.66 (0.20)

8.0 – 25.0

A1A Bridge

6.48 (2.87)

16.66 (9.75)

20.0 – 31.0

 

Compared with salinities of the previous week, average salinity in the estuary increased only slightly in the upper estuary (<1 ppt) to about 4-7 ppt in the lower estuary at A1A Bridge.  All four monitoring stations are reporting salinities below the preferred range.  Salinity conditions in the estuary are considered to be poor based on the salinity preference of the oyster, Crassostrea virginica, and location in the estuary.

 

Caloosahatchee Estuary

 

An average weekly discharge of 6191 cfs occurred at S-79 and 2136 cfs at S-77.  The concentration of chlorides at the Olga Plant was 40 ppm yesterday, up from 30 ppm at the beginning of this reporting period.  An average discharge of 3708 cfs occurred at S-78 over the past week.

 

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)

0.21 (0.16)

0.22 (0.15)

Rt. 31 Bridge

0.21 (0.16)

NR (NR)

I-75 Bridge

0.24 (0.20)

0.22 (0.18)

Ft. Myers Yacht Basin

0.23 (0.19)

0.23 (0.19)

Cape Coral Bridge

1.15 (0.54)

1.60 (1.13)

Shell Point

11.16 (7.69)

16.62 (11.45)

 

In the estuary, freshwater conditions extend from S-79 downstream to Cape Coral Bridge.  Salinity conditions in the upper estuary east of Ft. Myers are good (30 day average at Ft. Myers = 0.42 ppt).

 

Salinity at Cape Coral Bridge is below the preferred ranges for both oyster, Crassostrea virginica, and seagrass, Halodule wrightii.  Salinity at Shell Point is oscillating with the tide between about 29 ppt to 3 ppt.  Therefore, conditions in the lower estuary between Cape Coral and Shell Point are considered poor.

 

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

 

Water Conservation Areas

 

Water depths in the Greater Everglades (GE) have increased by 1 foot during the last month almost everywhere.  Depths now range from a high of 4.28 feet in WCA-2B to a low of 1.5 foot in NE Shark River Slough. The Greater Everglades has now reached a state where large areas of the GE are currently over 2.5 feet.  This 2.5 foot depth is a generalized threshold for tree island inundation where continuous inundation of more than 120 days is a potential health hazard for islands.  Thus, Inundation Days are now being tracked, and some areas of WCA-3A are now 42 days above the tree island threshold.

 

WCA-1 has dropped below the regulation schedule.  All the other WCA stages are above regulation, especially WCA-2A, which has been above regulation since Oct. 1, 2007 (i.e., the last 11 months). It is not possible to restore drowned tree islands in WCA-2A under this hydrologic regime.

 

Everglades National Park

 

Stages in Everglades National Park (ENP) wetlands declined last week.  Water levels were down by approx. 1.9 inches last week in Shark River Slough (station P33), and by just over 1 inch in other areas of the Park (ENP panhandle, Taylor Slough Bridge, & Craighead Pond).

 

Salinity trends across Florida Bay were mixed.  In the eastern Bay (Duck Key, L. Madeira Bay mouth) salinity held in the lower-mid 30s for much of the week.  Taylor River pond salinity fell below into the teens last week, before quickly increasing by the weekend into the lower-mid 20s (NOTE: salinity here is still high as September concentrations average below 5 psu).  The Taylor River (TR) 30 day moving average salinity (used for tracking the FL Bay MFL criterion) decreased again from last week’s reading (28.6 psu), down to 23.2 psu as of Sunday, 9/7.  The central Bay platform at Whipray Basin experienced a slight increase in salinity last week, up into the lower-40s.  Salinity held near seasonal concentrations in upstream reaches of Shark River (Tarpon Bay platform, where salinity is nearly fresh @ below 1 psu).

 

Water Supply

 

Water levels declined slightly across most of the District after enjoying a substantial rise (increase) as a result of Tropical Storms Fay and Hanna.  Water levels in the upper and lower Kissimmee Basin are now slightly above their average conditions for their respective periods of record.  Water levels in the Lower West Coast are mostly above their historical averages and are now above levels that were recorded in 2006.  Water levels in the Lower East Coast are now above their historical averages – although they have declined over the past week as a result of pre-storm management.  Water levels in the Upper East Coast remain significantly above their historic averages and are close to their highest recorded values.

Surface and groundwater levels in Water Conservation Areas 1, 2 and 3 are now slightly above their historic averages this week – the highest recorded levels were within Water Conservation Area 2.

 

Eight 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.  The projected Lake Okeechobee Stage is now in the “low” risk category.

 

Three out the eleven water supply risk indicators are now in the “medium” risk category, including LEC Service Areas 1, 2 and 3 as a result of the water restrictions that are now in place.

 

LORS2008 (Lake Okeechobee Regulation Schedule)

 

Stages in Lake Okeechobee have risen to within one foot of the intermediate band, which calls for discharges of up to 4000 cfs at S-77 and up to 1800 cfs at S-80.  The United States Army Corps of Engineers (USACE) initiated discharges on September 4th.

 

 

 

 

 

CC:      George Horne