MEMORANDUM

 

 

TO:            Chip Merriam, Deputy Executive Director, Water Resources

 

FROM:      SFWMD Staff Environmental Advisory Team

 

DATE:       April 8, 2008

 

SUBJECT: Weekly Environmental Recommendation for Systems Operations

 

Recommendation

 

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

 

Background

 

Showers south today, then drier.  A frontal boundary is becoming diffuse across the area and an upper level energy impulse is tracking eastward through the Florida Straits.  Expect some patches of light rain mixed with embedded showers to move across the southern half of the District today.  A drier pattern is forecast to set up Wednesday with just some spotty shower activity through Saturday.   A cold front is expected to bringing light to moderate shower activity Saturday night and Sunday.  The next ten days precipitation outlook is below average with moderate confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 3.57 inches of rainfall to bring the 30 day total to 4.27 inches (140% of average), and the lower basin received 3.39 inches to bring the 30 day total to 4.39 inches (160% of average).

 

The discharge from Lake Kissimmee (S-65) continues in the range of 1500-2000 cfs to continue a gradual water level recession and provide flow to the Kissimmee River.  Releases are no longer being made from Lake Toho (S-61) or East Lake Toho (S59).  Releases from Lake Gentry are being made at 970 cfs.   No other releases are being made in the upper basin.

 

Snail kites continue to nest on East Lake Toho, Lake Toho, and Lake Kissimmee.  A whooping crane continues to nest on Lake Kissimmee.

 

Flow has been reestablished to the Kissimmee River for 258 days (S-65 re-opened on 07/18/07).  The inflow from the upper basin continues to inundate a portion of the floodplain in the Phase I area of the Kissimmee River Restoration Project.  Dissolved oxygen concentrations in the river channel of the Kissimmee River ranged from 2.3 mg/L to 7.6 mg/L with an average of 3.8 mg/L.

 

Lake Okeechobee

 

According to the USACE web site, Lake Okeechobee stage is 10.48’ NGVD, which is 0.19’ higher than a week ago and 0.38’ higher than a month ago.  The current stage is 0.39’ higher than it was a year ago and 3.75’ below its historical average for this time of year.  Total inflows exceed 4500 cfs and include the Kissimmee River (~1800 cfs), S71 and S72 (~1800 cfs), S84 (~150 cfs), S77 (~100 cfs), and the L8 at Canal Point (~730 cfs).  No outflows are reported.  Weekend rainfall totals at sites around the lake ranged from 1.50” at the Okeechobee Field Station to 3.74” at the S77.

 

Monthly phytoplankton monitoring was performed on March 26th.  Six of nine sites had sufficient water for sampling.  Mean secchi depth was 0.18 m.  Chlorophyll and toxin data are not yet available, but there was no visual evidence of bloom conditions at any of the sites.

 

St. Lucie Estuary

 

There were no releases through S-80 over the past week.  There was very little discharge at S-49 on the C-24 canal and no discharge at S-97 on the C-23 canal.  The current weekly average salinities (in bold) at the four monitoring sites in the St. Lucie Estuary are given below in parts per thousand (ppt).  Current weekly averages may be compared with the previous week’s data (in parenthesis).

 

 

Weekly Average Salinity (ppt)

 

Sampling Site

Surface

Bottom

Envelope

Palm City Bridge (S. Fork)

11.55 ( 11.77)

12.64 (12.99)

 

HR1 (N. Fork)

12.09 (15.77)

13.45 (NR)

 

Roosevelt Bridge

16.22 (17.87)

16.98 (18.55)

8.0 – 25.0

A1A Bridge

25.35 (26.93)

27.56 (29.10)

20.0 – 31.0

 

In general, average salinity decreased during the past week throughout the estuary.  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.  The current surface salinity of 16.22 ppt at the Roosevelt Bridge is 11.78 ppt below the maximum weekly average of 28.0 ppt achieved in May 2001 during the 2000 – 2001 drought.

 

Caloosahatchee Estuary

 

Weekly average discharge of 197 cfs occurred at S-79 last week.  Discharge from S-77 into Lake Okeechobee averaged 77.71 cfs.  The concentration of chlorides at the Olga Plant is 163 mg/l. 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)

14.45 (15.05)

14.50 (16.12)

Rt. 31 Bridge

15.06 (14.19)

16.15 (18.87)

I-75 Bridge

NA (14.71)

20.17 (19.52)

Ft. Myers Yacht Basin

23.19 (21.67)

23.32 (23.94)

Cape Coral Bridge

28.06 (27.65)

28.77 (29.00)

Shell Point

34.33 (33.97)

35.22 (34.93)

 

Compared with last week, average surface salinities decreased only at S79.  Average bottom salinities decreased for most sites in the estuary.  Salinity at the Ft. Myers surface sensor remains above the 1-day MFL criterion of 20 ppt.  The current surface salinity of 14.45 ppt at S-79 is 5.55 ppt below the maximum weekly average of 20.0 ppt achieved in May 2001 during the 2000 – 2001 drought.  Salinity at the Cape Coral Bridge is near the upper limit of the optimal range for the oyster, Crassostrea virginica.  Conditions in the upper estuary east of Ft. Myers are poor due to high salinity.  Conditions downstream of Cape Coral are fair considering the salinity tolerances of oysters.  FWRI reports that no Karenia brevis, the Florida red tide organism, was detected this week in water samples collected alongshore between Pinellas and Monroe counties.

 

Water Conservation Areas

 

While rainfall is generally welcome in a drought, it has continued to interfere with the traditional breeding patterns of wading birds in the Everglades.  Water levels rose throughout the Everglades.  Stages increased the most in northern WCA-3A, where the greatest rain fell, and least in WCA-3B.  The high rainfall has produced large reversals throughout the Everglades, ranging from 0.05” up to 0.68”, producing poor foraging conditions for wading birds.  (Optimal recession rates are declines of 0.04-0.16’ per week.)

 

Depths similarly were poor for wading birds throughout the region, ranging from 0.89’ to 2.56’ in the Conservation Areas.  Wading birds in general need water depths from 0.1’ to 0.79’ to find appropriate prey species.  The current water depths do not support foraging, which is increasing concern for wading bird breeding success this year.  However, as reported last week, it is still relatively early in the nesting season for ibis and it is hoped that these poor hydrologic conditions will have a minimum impact on this species.

 

Marsh stages in WCA-1 have risen again and are above Regulation, WCA-2A marsh remains at levels above regulation and canals have likewise risen, and WCA-3A stages have reached the top of zone E1 of the regulation schedule, which is designed for protection of the Cape Sable Seaside Sparrow.

 

Everglades National Park

 

Everglades National Park (ENP) and Florida Bay saw substantial rainfall last week, particularly Sunday with 7 day accumulations ranging between 0.7” – 2.6”.  The basin-wide spatially-averaged Raindar totals for the week were 1.8” for the ENP basin and 2.0” in the C-111 basin; precipitation is not accounted for yet in description of stage/salinity trends below.

 

ENP wetland water levels showed mixed trends last week, due in part to the timing and distribution of Sunday’s rain event.  Water levels were down in both northern and southern areas of Taylor Slough; at Taylor Slough Bridge daily mean water levels dropped by 4.3” over the week (not unusual for this station, and hourly measurements showed it rising quickly after Sunday’s rain event).  To the south in Craighead Pond, stage decreased by 1.2” for the 7 day period.  In the Shark River Slough system, though, water levels increased by just over 2.5” at station P33 over the week, in response to heavy rainfall in this area over the past 2 weeks.  Data from the panhandle (station EVER6) have been unreliable of late.

 

The salinity pattern in Florida Bay and surrounding embayments was also variable last week.  Salinity remained just above 30 psu at Trout Creek.  A flow reversal in Taylor River increased salinity into the upper-20s at the mouth and up towards 25 psu in the ponds (at both Pond 5 (USGS station) and Argyle Hendry (ENP station TR)).  As of Sunday, the 30 day moving average concentration at Taylor River, used for tracking the Florida Bay MFL criterion, was at 13.7 psu, up from 9.5 psu last week, and while not unseasonably high, the highest concentration we have seen yet this dry season.  The station at the Little Madeira Bay mouth remains offline.

 

Strong flow reversals pushed Bay water northward into the north central Bay areas of McCormick Creek and Terrapin Bay, increasing salinity concentrations into the mid-30s.  Data from the central Bay station at Whipray Basin continue to be patchy, so rainfall data haven’t been updated.  In contrast to trends elsewhere in the Bay, and probably the result of local rainfall, salinity in Whipray declined a bit last week to 37 psu over the weekend.

 

As a whole the regional salinity concentrations are near seasonal norms except out west in areas downstream of Shark River Slough (upstream reaches of Shark River) in Tarpon Bay.  There the daily mean measurement of 19 psu on Sunday is still well above normal for this station, closer to concentrations experienced at the height of the dry season in May, not surprising with the low water levels and flows through SRS this water year.

 

Wildlife:

 

Spoonbill nesting: - Audubon reported Spoonbill nesting in Eastern Florida Bay at 3 nests, all of which were monitored.  In late March, 1 nest failed and 1 chick survived to 21 days.  In Western Florida Bay, significant colony activity was detected in late January, likely a second nesting attempt by birds at Palm Key.  While they haven’t visited the site yet, they saw more than 40 adults and at least 5 large chicks at the colony.  Audubon staff plan to visit the site this week.  With the rainfall, stages should rise substantially this week.

 

Other wading birds: - The colony flight on Tuesday, April 1, was notable for the absence of wading birds in the northern Everglades.  Scientists counted a total of only 605 nests (585 Great Egret and 20 White Ibis nests), in sharp contrast to the April counts of 2006 and 2007 when they observed approximately 37,000 and 18,000 nests, respectively.  April tends to be the month of peak nesting activity, and we could yet see a late surge in ibis nesting activity if foraging conditions improve soon.  However, it is now highly unlikely that storks will initiate breeding.

 

Most areas of the WCAs were largely devoid of birds. Northwest WCA-3A supported moderate numbers of birds, including storks and spoonbills but scientists noted no large foraging flocks. A few large flocks of ibis were observed in western WCA-1 but few birds were seen elsewhere in the Refuge (see nest numbers table for more details).

 

Water Supply

 

Water levels in the upper and lower Kissimmee Basin are now near their historical average conditions for this time of year – they rose somewhat this past week as a result of local rains.  Water levels in the Lower West Coast are a “mixed bag” of slightly higher and lower than historical averages, depending on the degree of confinement of the aquifers.  Water levels in the Lower East Coast are near or slightly above their historical averages and most wells recorded modest increases in water levels this past week.  Water levels in the Upper East Coast remain well above their historic averages.  Surface and groundwater levels in Water Conservation Areas 1 and 2 are now above their historic averages as a result of local rainfall.  Water levels in WCA 3A have rebounded to near their historic averages this week.  Water levels in the southernmost portion of Miami-Dade County are now near or slightly above their average historic conditions.

 

There was continued modest improvement in the Water Supply Risk indicators this week.  Four out of eleven risk measures are in the “high” risk category including the projected Lake Okeechobee Stage (SSM), and Lower East Coast service areas 1, 2 and 3.

 

The Palmer Index for Lake Okeechobee tributary conditions and Climate Prediction Center Precipitation Outlook are now in the “medium” risk category.

 

The Lake Okeechobee Seasonal and Multi-seasonal Net Inflow Forecasts are now at “low” this week.  Water Conservation Areas 1, 2A and 3A continue to be in the “low” risk category.

 

WSE (Lake Okeechobee Regulation Schedule)

 

The current Lake Okeechobee 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 Niña climactic conditions.

 

CC:   George Horne