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:                        April 21, 2009

 

SUBJECT:     Weekly Environmental Conditions for Systems Operations

 

Summary

 

Discharge from Lake Kissimmee is approximately 250 cfs and will be incrementally increased to approximately 1000 cfs.  Lake Okeechobee stage is 11.52 feet NGVD, which is 0.28 foot lower than a week ago, 0.83 foot lower than a month ago, 1.10 feet higher than it was a year ago, and 1.12 foot lower then the simulated average using the current regulation schedule.  Salinity conditions in the Saint Lucie estuary are considered to be fair based on the salinity preference of the oyster, Crassostrea virginica, and location in the estuary.  In the Caloosahatchee Estuary, salinity conditions are poor in the upper estuary, good in San Carlos Bay and good in the lower estuary.  The Corp’s most recent pulse release to the Caloosahatchee Estuary ended on Friday.

Water level recession rates are considered fair or good for wading bird feeding in most of WCA-1 and middle WCA-3A and -3B.  Groundwater levels continue the current downward trend across most of the District. 

 

Background

 

Showers ending; becoming warm and dry.  Showers associated with a cold front are exiting the District.  Drier air is quickly moving in behind the front with strong high pressure.  This high will move slowly west to east of the peninsula over the next few days.  Garbage showers could return east over the weekend, but the next chance for appreciable rain is about ten days away.  The next ten days precipitation outlook is below average with moderate confidence.

 

Kissimmee Watershed

 

Over the last seven days, the upper Kissimmee Basin received 0.62 inches of rainfall and the lower Kissimmee Basin received 0.49 inches (Daily Rainfall Report 4/21/09).

Stages in Lakes Kissimmee, Hatchineha and Cypress are 0.68 feet below regulation schedule.

Lakes Tohopekaliga and East Tohopekaliga are now at or very close to their regulation schedules.  The Alligator chain of lakes is 0.43 feet below regulation and Lake Gentry is 0.47 feet below regulation schedule.  Lakes Hart and Mary Jane are very close to regulation schedule.

 

Preliminary numbers for the most recent snail kite nesting survey are as follows:

 

Lake Tohopekaliga – 36 nests

East Lake Tohopekaliga – 7 nests

Lake Kissimmee – 16 nests

Lake Hatchineha – 1 nest

Lake Jackson – 1 nest

Lake Istokpoga – 7 nests

 

Discharge from East Lake Tohopekaliga and Lake Tohopekaliga are 225 cfs and 660 cfs, respectively.  Discharge from Lake Kissimmee continues at about 250 cfs but will need to be increased to approximately 1000 cfs soon, to stay within the regulation schedule.  The floodplain of the Kissimmee River is essentially dry.

 

A slight turbidity plume (presumably from the ongoing construction) is visible in lower Pool B/C and northern Pool D.

 

Wading bird numbers are low except around drying pools near the active construction area in northern Pool B/C.

 

Discharge at S65C is about 350 cfs.

 

Over the last seven days, dissolved oxygen concentrations in the Kissimmee River ranged from 4.8 mg/L to 8.5 mg/L and averaged 7.1 mg/L

 

Lake Okeechobee

 

According to the United States Army Corps of Engineers web site, Lake Okeechobee stage is 11.52 feet NGVD, which is 0.28 feet lower than a week ago, 0.83 feet lower than a month ago, and 1.10 feet higher than it was a year ago.  The current stage is 2.35 feet below the historical average for this date and 1.12 feet below the simulated average using the current regulation schedule (LORS2008).  Total reported inflows are 64 cfs and are limited to flows through S65E.  No inflow data are reported for S129, S133 and Fisheating Creek.  Total outflows are 2518 cfs and include releases to the Caloosahatchee River (274 cfs), water-supply releases through the S351, S352 and S354 (1727 cfs) and to the L8 at Canal Point (23 cfs), and flow (494 cfs) through the S308.

The monthly submerged-aquatic-vegetation (SAV) survey was completed last week.  A total of 38 sites were sampled this month (24 in the north, 7 in the west, 7 in the south) and plants were found at 22 of those sites (18 in the north, 4 in the west, 0 in the south).  Two sites were dry (1 in the north and 1 in the west) and 1 site in the north was too shallow to sample. Last month, 39 sites were visited and 21 had plants.  In the north, numerous dense beds of Vallisneria, Hydrilla, and Ceratophyllum were observed.  The innermost sites in the south are still mostly dominated by cattail and spikerush and too dense to sample effectively although attempts to sample yielded no SAV.  All of the sites along the western wall have dense beds of topped out and reproductive Vallisneria, so fostering conditions that would allow the lake stage to remain above 10.5 feet would be beneficial to continued SAV expansion.

Monthly phytoplankton monitoring was performed at eight of the nine sites last week.  One site was too shallow to effectively sample.  No blooms were detected at any of the sites although green flecks were observed in the water column at two of the northern sites (at the mouth of the Kissimmee and around Taylor Creek).  Mean secchi depth was 0.62 meters (compared to 0.42 meters in March). Secchi depths of over 0.5 meters were seen at all sites except Pahokee, Clewiston and the mouth of the Kissimmee.  March microcystin levels were at or below the 0.2 ppb detection limit at all sites.

This week, scientists from the District and Harbor Branch Oceanographic Institute will be tagging approximately 1,600 juvenile Florida apple snails (Pomacea palludosa) for release into a small marsh at the north end of Lake Okeechobee.  The snails, which are the sole food source for the endangered Everglades Snail Kite (Rostrhamus sociabilis), were reared in an aquaculture facility at Harbor Branch from eggs collected in Lake Kissimmee. Once released, the dispersal and survival of the snails will be monitored.  This effort is being done with the hopes of facilitating the re-establishment of this critical species as the prolonged drought conditions during the past year have resulted in the loss of apple snail populations across most of the littoral zone of Lake Okeechobee.

 

Saint Lucie Estuary

 

Over the past week, no discharge occurred at S-80.  Discharge from the Lake at S-308 averaged 250 cfs.  Provisional data indicates that no discharge occurred at S-97 on C-23 and S-49 on C-24.  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 (South Fork)

20.5 (20.7)

21.5 (21.1)

 

HR1 (North Fork)

24.8 (23.8)

25.7 (24.6)

 

Roosevelt Bridge

27.3 (26.2)

27.5 (26.5)

8.0 – 25.0

A1A Bridge

31.6 (30.4)

33.4 (32.1)

20.0 – 31.0

 

Salinity throughout the estuary increased slightly last week.  At both the Roosevelt and A1A Bridges, weekly average salinity is slightly above the upper bound of the preferred range.  Salinity conditions in the estuary are considered to be fair considering the time of year, the location in the estuary, and salinity preference of the oyster, Crassostrea virginica.

 

Caloosahatchee Estuary

 

During the past week, discharge averaged 324 cfs at S-79, 277 cfs at S-78, and 703 cfs at S-77.  The concentration of chlorides at the Olga Plant was 129 ppm yesterday.  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)

5.3 (5.5)

6.4 (6.4)

Rt. 31 Bridge

5.3 (7.6)

7.0 (9.0)

I-75 Bridge

6.0 (9.7)

9.6 (11.4)

Ft. Myers Yacht Basin

14.8 (17.8)

18.5 (18.6)

Cape Coral Bridge

24.7 (25.9)

25.2 (26.9)

Shell Point

34.1 (34.2)

34.5 (35.2)

 

The seven day pulse release at S-79 ended on Friday, 4/17/09.  Average salinity decreased slightly throughout the estuary.  Conditions in the upper estuary east of Ft. Myers are poor (30 day average at Ft. Myers = 17.9 ppt).  Salinities at the Cape Coral Bridge are within the preferred range for the oyster, Crassostrea virginica, and well within the range tolerated by seagrass, Halodule wrightii.  Therefore, conditions in the lower estuary are good.  Salinity at Shell Point indicates that conditions are good in San Carlos Bay.

 

Fish and Wildlife Research Institute reports that water samples collected alongshore between Pinellas and Sarasota counties contained no Karenia brevis (red tide).  Counts from samples collected alongshore of Lee County ranged from not present to present.  Monitoring data collected by the River, Estuary and Coastal Observing Network (RECON) of Sanibel-Captiva Conservation Foundation (SCCF) indicated DO concentration at Fort Myers and Shell Point ranged from 4.8 to 7.9 mg/L and chlorophyll at Ft. Myers and Shell Point ranged from 1.1 to 7.6 mg/L.

 

Water Conservation Areas

 

Water levels are falling at rates considered Fair or Good for wading bird foraging in WCA-3, but in WCA-1, the rainfall on April 20-21 caused a general reversal of some 0.10 to 0.20 feet over a single day:

 

Stage Change:            WCA-1:           +0.06 foot        WCA-3A:         -0.01 foot

                                    WCA-2A:         -0.00 foot         WCA-3B:         -0.07 foot

                                    WCA-2B:         -0.13 foot         NESRS:          -0.11 foot

 

All WCAs are below their regulation schedules.

 

Despite the recent rains, water depths continue to be largely below ground in much of the EPA.  Water is still available for foraging by wading birds in WCA-1 and WCA-3A and 3B.

 

As water depths continue to decline, there is a loss of peat through decomposition and a higher possibility of muck fires.  Most of the Everglades Protection Area (EPA) continues to be in the low to moderate muck fire risk categories.

 

Everglades National Park

 

Very little rain fell across Everglades National Park (ENP) and Florida Bay last week and, as a result, stages continued to drop last week.  Water levels in Shark River Slough and at the Taylor Slough Bridge dropped by 2.5 inches and 4.2 inches, respectively.  To the south, water levels in the ENP panhandle and at Craighead Pond dropped by 2.9 inches and 2.8 inches, respectively.

 

Salinity mostly increased in Florida Bay last week.  In the nearshore eastern Bay, salinity increased into the upper 30s in Long Sound and at the Little Madeira Bay, and remained in the upper 30s farther into the Bay at Duck Key.  The 30 day moving average salinity at the Taylor River platform (used for tracking the Florida Bay Maximum Flows and Levels-MFL) increased from 28.0 psu (4/12) to 30.2 psu (4/19), and the daily mean salinity stands at 34.6 psu (4/19).  NOTE: this week’s Taylor River 30 day moving average salinity value has exceeded the Florida Bay MFL criterion of 30 psu, and the timing of this year’s exceedance comes more than a month earlier than in 2008 when the Florida Bay MFL was exceeded on 5/24. At the central Bay platform in Whipray Basin, salinity increased to 47 psu.

 

Water Supply

 

Groundwater levels across the District continue to decline.  Floridan aquifer wells in the Kissimmee Basin remain between the lowest 30 and 10 percentile of their periods of records for this time of year, while continuing a steady decline.  Surficial aquifer wells in the Kissimmee Basin are declining steadily, with water levels between the 10th and 1st percentile ranges.  Canal stages in the Upper East Coast (UEC) are still about 1 ½ feet above the 14 foot agricultural pumping cutoff criteria due to recent rains, and the C-25 canal is over three feet above the cutoff level.  Groundwater levels in the northern UEC are declining – northern St. Lucie County well STL-125 is 0.2 feet above its all-time low.  In the southern coastal part of the UEC, groundwater levels are declining but remain higher than further north as a result of the boost from March rains.  Inland UEC well levels are steadily declining, with most reporting levels in the lowest 10th to 1st percentiles of their histories.  In the Lower East Coast, groundwater levels in southern Palm Beach and northern Broward counties remain high and are slowly declining.  Southern coastal Broward and Miami-Dade wells have higher water levels with respect to their periods of record than do wells located further inland.  Conditions are very dry in western/central Miami-Dade County, particularly in the area between Tamiami Trail and Homestead/Florida City, where levels have dropped to or slightly below those seen in early March.  The Surfical and Lower Tamiami aquifer levels in the Lower West Coast (LWC) are declining, with most wells reporting levels that are similar to those seen at this time in both 2007 and 2008.  Lower Tamiami aquifer water levels appear to be declining at a slower rate than Surfical levels. Sandstone aquifer levels in the LWC are very low, particularly in Lee County near Lehigh Acres.  Sandstone aquifer levels are now very close to 2007 conditions, which were several feet lower than at this time in 2008.  Mid-Hawthorn aquifer levels in the LWC are close to median values near the coast and are generally between the 30th and 10th percentile range further inland.  Mid Hawthorn levels are lower than last year, but not as low as at this time in 2007.

 

Water supply risk indicators in the "low" risk category include the Water Conservation Area 3A, the Lake Okeechobee (LOK) Seasonal Net Inflow Forecast and the LOK Multi-Seasonal Net Inflow Forecast.  The CPC Precipitation Outlook, the Palmer Index for LOK Tributary Conditions, and the projected LOK Stage for the next two months continue in the "medium" risk category.  Water Conservation Area 1 has moved into the "medium' risk category this week as well.  The water supply risk indicator for the entire LEC is in the "medium" risk category, with two days per week watering restrictions in place except for the utilities at risk.  Water Conservation Area 2A remains in the "high" risk category, with headwater elevation at S11B below Line 2 (9.81 feet).

 

LORS2008 (Lake Okeechobee Regulation Schedule)

 

 

Stages in Lake Okeechobee are now in the Beneficial Use sub-band.  Tributary inflows are currently in the dry category.  The seasonal outlook for net inflow into the lake is for wet conditions.  The multi-seasonal outlook is very wet.

 

On Saturday, April 11, the Corps initiated a nine-day pulse release to the Caloosahatchee Estuary that will average 650 cfs per day.  Flows from this pulse release ended on Friday, 4/17.

 

 

 

CC:      George Horne