South Florida - Thursday March 14, 2024: The South Florida Water Management District (SFWMD) Staff Environmental Advisory Team issues the following environmental conditions report for the areas under its responsibility.
Weather Conditions and Forecast
The lack of moisture and strong stability of the atmosphere will mean dry weather, with the prospect of any rain on Wednesday diminished. A warming trend will progress further late this week. Although moisture levels on Thursday will be fairly high, the strong stability of the atmosphere would seem to preclude any rain. However, with enough daytime heating, isolated afternoon showers could develop over portions of the southwestern interior and north of Lake Okeechobee. Over the weekend, a greater import of warm air and perhaps near-record high temperatures along with strong atmospheric stability will inhibit any rainfall. A cold front will push through north Florida early on Monday.
A good supply of deep moisture forced ascent from the frontal boundary, very favorable jet-stream winds, and enhanced instability could cause a round of afternoon rains, some moderately heavy, north of Lake Okeechobee. Widely scattered activity seems possible, particularly along and near the middle and upper east coasts of the SFWMD. Some severe weather could also occur.
Widespread rainfall is predicted north of the Lake, while substantially lower rainfall totals are likely over the far southern part of the SFWMD. For the week ending next Tuesday
morning, total SFWMD rainfall will most likely be much below normal and below normal if Monday’s rainfall is heavier than currently forecast. For the week-2 period (19-25 March), there is a strong signal for much above normal rainfall, partially related to an enhanced southern jet stream.
Lake Okeechobee
Lake Okeechobee stage was 15.94 feet NGVD on March 10, 2024, which was 0.18 feet lower than the previous week and 0.41 feet lower than a month ago. Average daily inflows (excluding rainfall) decreased from the previous week, going from 2,710 cfs to 2,520 cfs. Average daily outflows (excluding evapotranspiration) increased considerably from the previous week, going from 5,030 cfs to 8,400 cfs. The March 11 satellite image from NOAA’s Harmful Algal Bloom Monitoring System suggested a moderate bloom risk along most of the western and southern shorelines of the Lake.
Estuaries
Total inflow to the St. Lucie Estuary averaged 2,981 cfs over the past week with 2,700 cfs coming from Lake Okeechobee. Mean surface salinities decreased at all sites over thepast week. Salinity in the middle estuary was in the lower stressed range (5-10) for adult eastern oysters.
Total inflow to the Caloosahatchee Estuary averaged 7,277 cfs over the past week with 4,969 cfs coming from Lake Okeechobee. Mean surface salinities remained the same at
S-79 and Ft. Myers, decreased at the remaining sites in the estuary over the past week.
Salinities were in the optimal range (0-10) for tape grass in the upper estuary. Salinities were in the damaging range (0-5) for adult eastern oysters at Cape Coral, in the optimal
range (10-25) at Shell Point, and in the upper stressed range (> 25) at Sanibel.
Stormwater Treatment Areas
For the week ending Sunday, March 10, 2024, 5,400 ac-ft of Lake Okeechobee water was delivered to the FEBs/STAs. The total amount of Lake releases sent to the FEBs/STAs in WY2024 (since May 1, 2023) is approximately 38,000 ac-feet. The total amount of inflows to the STAs in WY2024 is approximately 1,375,000 ac-feet. Most STA cells are near or above target stage. STA-1E Eastern Flow-way is offline for erosion repair in Cell 2. Operational restrictions are in effect in STA-1E Western Flow-way, STA-1W Northern Flow-way, STA-2 Flow-ways 2 and 4, STA-3/4 Eastern Flow-way, and STA-5/6 Flow-way 4 for vegetation management activities. This week, if 2008 LORS recommends Lake releases to the WCAs and conditions allow, releases will be sent to STA-5/6.
Everglades
Last week’s rates of stage change (Sunday to Sunday) were generally unfavorable for wading bird foraging and nesting. Stage change in Taylor Slough was minimal last week, but depths remain well above the recent average. Salinity change increased in Florida Bay again last week, however conditions remain below the 25th percentile for this time of year in all regions with the eastern and central regions very well positioned for this time of year. Numbers of foraging wading birds continued to decline, and nesting is limited.
Biscayne Bay
Total inflow to Biscayne Bay averaged 626 cfs and the previous 30-day mean inflow averaged 646 cfs. The seven-day mean salinity was 21.9 at BBCW8 and 20.0 at BBCW10, both within the ideal salinity range for estuarine organisms in this region (salinity less than 35). Data provided by Biscayne National Park.
Water Management Recommendations
Continue the stage recessions in Lakes East Toho and Toho to reach their low pools on May 31, 2024. Follow the Hybrid A discharge plan for S-65/S-65A (Fig. KB-7) through May 31, 2024, except as otherwise indicated. Maintain at least minimum flow (250-300 cfs) at S-65A. Continue the S-65/S-65A flow rampdown to ~700 cfs to facilitate S-69
repairs. To the extent possible, modify S-65D headwater stage to meet USACE's objectives for S-69 repairs.