MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       January 15, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Some showers by the end of the week.  Cooler and dry conditions will move over the area as a cold front clears the south end of the peninsula today.  The first in a series of upper level impulses will move across north Florida Thursday morning.  This impulse will pull the front back north Wednesday generating scattered shower activity mainly over the interior.  As the impulse moves across the area and then pushes the cold front back south of the District, expected showers and a couple of thunderstorms mainly north Thursday and then mainly south Friday.  A potential for a couple of moderate rainfall days exists as a second impulse moves across the area Sunday and then a third impulse moves across Tuesday.  The next ten days precipitation outlook is above average with moderate confidence.

 

Kissimmee Watershed

 

Over the last 7 days, the upper Kissimmee Basin received 0.16 inches of rainfall to bring the 30-day total to 0.49 inches, which was 20% of the long term average, and the lower basin received 0.01 inches to bring the 30-day total to 0.36 inches, which was 20% of average.  Water levels in all of the upper basin lakes, except Lake Toho, have continued to decline.  All lakes are below regulation schedule.  Lakes Kissimmee, Hatchineha and Cypress are approximately 2.5 ft below regulation level.

 

The only releases being made in the upper basin are at S-65, which is discharging approximately 250 cfs.  Flow has been reestablished to the Kissimmee River for 174 days (S-65 re-opened on 07/18/07).  In the river channel of the Kissimmee River, the concentration of dissolved oxygen ranged from 4.4 mg/L to 6.4 mg/L (mean 6.6 mg/L) for the last six days

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.09’ NGVD, which is 0.04’ lower than a week ago and 0.23’ lower than a month ago.  The current stage is 1.88’ lower than it was a year ago and 4.68’ below its historical average for this time of year.  Inflows from the Kissimmee River (S65E) continue at approximately 250 cfs and periodic outflows to the Lake Istokpoga Service Area are occurring through the G207 and G208.

 

In December, 24 of the 27 water quality sampling sites had sufficient water for sampling.  Preliminary lake-wide, TP averaged 97 ppb and TSS averaged 21 mg/L.  These concentrations are lower than those measured in November.  Preliminary average TP at near shore sites decreased from 80 ppb in November to 54 ppb in December and TSS decreased 19 mg/L to 10.5 mg/L.

 

The monthly submerged-aquatic-vegetation (SAV) survey was completed last week.  The macroalga Chara remains the dominant SAV species and was found at 12 of the 24 sites sampled.  This distribution is lower than that reported in November, with slight reductions in the density of Chara despite continued good to excellent water clarity (secchi depths 50-100% of total depths).  One species of vascular SAV, Vallisneria americana, continues to be present in very low density at a few sites behind King’s Bar on the northern shoreline.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  Discharge at S-97 on the C-24 Canal and at S-49 on the C-23 canal averaged < 1.0 cfs.  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)

9.4 (9.3)

12.3 (11.2)

 

HR1 (N. Fork)

13.2 (13.3)

15.5 (15.7)

 

Roosevelt Bridge

16.6 (16.5)

16.7 (17.1)

8.0 – 25.0

A1A Bridge

24.2 (24.5)

26.7 (27.3)

20.0 – 31.0

 

Average salinity changed only slightly during the past week.  Both the surface and bottom salinity are in the preferred range at the Roosevelt Bridge, and at the A1A Bridge.  Based on the salinity tolerances of the oyster, Crassostrea virginica, salinity conditions in the estuary are good.

 

FWRI reports that in Indian River and St. Lucie counties, samples collected within the Indian River Lagoon contained concentrations of Karenia brevis, the Florida red tide organism, ranging from not present to very low.  Oceanside samples collected between Brevard and Martin counties contained no K. brevis.

 

Caloosahatchee Estuary

 

No discharge occurred at S-79 last week.  The concentration of chlorides at the Olga Plant is 167 mg/l.  Average salinity increased over the past week.  Weekly average salinities for specific sites are given below in parts per thousand (ppt).  Current weekly averages (in bold) may be compared to last week’s data (in parenthesis).

 

 

Weekly Average Salinity (ppt)

Sampling Site

Surface

Bottom

Franklin Locks (S-79)

18.7 (14.8)

18.7 (15.5)

Rt. 31 Bridge

17.4 (14.4)

19.1 (15.5)

I-75 Bridge

NA (14.6)

21.8 (18.3)

Ft. Myers Yacht Basin

23.0 (20.1)

24.0 (21.0)

Cape Coral Bridge

25.7 (26.9)

29.0 (27.9)

Shell Point

33.7 (NA)

35.5 (NA)

 

Conditions in the upper estuary are poor due to high salinity. The current salinity of 18.7 ppt at S-79 is 2.6 ppt below the maximum weekly average of 21.0 ppt recorded in May 2001.  Salinity at the Cape Coral Bridge is at the upper limit of the optimal range for the oyster, Crassostrea virginica.

 

FWRI reports that water samples collected alongshore this week between Pinellas and Monroe counties contained no Karenia brevis, the Florida red tide organism.

 

Water Conservation Areas

 

Overall good dry-season recession rates continue to dominate the region.  Northern and central WCA-3B continues to have fair recession rates due to little change over time.  Although recession rates were good, the depths in the Everglades remain too deep for wading bird foraging.  This is normally not an issue at this time of year because foraging in support of nesting behavior does not usually begin until February.  Only the northern (north of I-75) sections of WCA-3A had proper depths and recession rates to support wading birds.  Stages in WCA-1 are slightly below Regulation, WCA-3 stages continue to be significantly below regulation, and WCA-2A remains above regulation.

 

Everglades National Park

 

Everglades National Park (ENP) wetland water levels continue to decline.  Taylor Slough Bridge saw the most substantial weekly drop of nearly 1.7”, which is not unusual for this station.  All other areas of ENP experienced a weekly decline of approx. 0.5” (areas including Shark River Slough at the P33 gage, the panhandle at the EVER6 gage, & Craighead Pond).

 

Salinity concentrations either remained stable or increased slightly in Florida Bay last week.  Salinity crept slowly upwards at the creek sites, into the upper-20s at Trout Ck. and into the upper teens at the mouth of Taylor River.  Effects from a flow reversal were evident in the Taylor River ponds as salinity increased throughout the week, up to just over 10 psu at Pond 5 and near 8 psu at Argyle Hendry (station Taylor River) as of Sunday, 1/13.  The 30 day moving average concentration at Taylor River (used to monitor exceedances to the FL Bay MFL rule) is still low at just over 2 psu.  Salinity concentrations at the Little Madeira Bay platform spent much of last week near 20 psu.  In the north-central Bay, salinity increased to 20 psu at McCormick Ck., and to 25 psu at Terrapin Bay.  The platform at Whipray Basin stopped sending data after 1/7, so cannot report on trends in the central Bay.  In the SRS outflow at Tarpon Bay, salinity was near 11 psu as of Sunday 1/13.  As of now, the Bay appears to be well buffered in terms of salinity for the dry season.

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin and Lower West Coast continued to decline this week – and are now below their historical average conditions for this time of year.  Water levels in the Lower East Coast are still slightly above their historical averages – although many wells recorded modest declines in the past week.  Water levels in the Upper East Coast continue to remain above their historic averages.  Surface and groundwater levels in Water Conservation Areas 1 and 2 are now near or slightly below their historic averages.  Water levels in WCA 3A continue to remain below their historic averages – and were somewhat lower this week.  Water levels in the southern-most portion of Miami-Dade County are now below average historic conditions.

 

Seven out of eleven water supply risk measures are in the “high” risk category - the projected Lake O Stage (SSM), the Palmer Index for Tributary Conditions, the CPC Precipitation Outlook, the LOK Seasonal Net Inflow Forecast and Lower East Coast Service Areas 1, 2 and 3.

 

Water Conservation Areas 1, 2A and 3A continue to be in the “low” risk category and the Multi-Seasonal Net Inflow Forecast remains at “medium” risk this week.

 

Chlorides at the Olga WTP on the Caloosahatchee River are now at 167 ppm and the plant is operational.

 

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake O stage remains in the Water Shortage Management zone and is unlikely to move back into Zone E in the next several months during the persistent La Nina climactic conditions.

 

 

 

 

 

 

 

CC:   George Horne