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SFWMD: Weekly Environmental Conditions Report


South Florida - Thursday May 16, 2024: A region of thunderstorms began to enter the SFWMD region early Wednesday morning. Some offshore shower and thunderstorm activity could move into portions of the southwest coast and Kissimmee Valley.

Numerous, potentially heavy, showers and thunderstorms are expected to be followed by a drying and stabilizing atmosphere, which will allow daytime temperatures to soar into the upper 90s F in some locations late this week and into the weekend. The next good chance of rain will come on Sunday or Monday.

Below normal total SFWMD rainfall is likely for the 7-day period ending next Tuesday morning.

To read the full report CLICK ON THIS LINK.


Releases were made from East Lake Toho and Lake Toho to continue spring lake stage recessions to low pool. Weekly average discharge on May 12, 2024, was 420 cfs and 360 cfs at S-65 and S-65A, respectively. Mean weekly water depth on the Kissimmee River floodplain decreased by 0.02 feet to 0.08 feet over the week ending May 12, 2024. The weekly average concentration of dissolved oxygen in the Kissimmee River decreased from 7.9 mg/L last week to 7.8 mg/L for the week ending May 12, 2024, which is well above the potentially lethal and stressful levels for largemouth bass and other sensitive species.

Lake Okeechobee
Lake Okeechobee stage was 12.46 feet NAVD88 (13.77 ft NGVD29) on May 12, 2024, which was 0.30 feet lower than the previous week and 1.19 feet lower than a month ago. Average daily inflow (excluding rainfall) was 360 cfs, lower than the previous week’s flow of 600 cfs. Average daily outflows (excluding evapotranspiration) increased from 4,290 cfs the previous week to 5,310 cfs this week. The May 10th, 2024, NOAA’s Harmful Algal Bloom Monitoring System suggested moderate to high cyanobacteria concentrations within much of the northeastern region of the Lake.

Total inflow to the St. Lucie Estuary averaged 70 cfs over the past week with all coming from the Tidal Basin. Mean surface salinities decreased at HR1 and increased at the remaining sites in the estuary over the past week. Salinity in the middle estuary was in the optimal range (10-25) for adult eastern oysters.

Total inflow to the Caloosahatchee Estuary averaged 1,861 cfs over the past week with 1,399 cfs coming from Lake Okeechobee. Mean surface salinities decreased at Fort Myers and increased 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 optimal range (10-25) for adult eastern oysters at Cape Coral, and in the upper stressed range (>25) at Shell Point and Sanibel.

Stormwater Treatment Areas
For the week ending Sunday, May 12, 2024, 11,000 ac-ft of Lake Okeechobee water was delivered to the FEBs/STAs. The total amount of Lake releases sent to the FEBs/STAs in WY2025 (since May 1, 2024) is approximately 18,200 ac-feet. The total amount of inflows to the STAs in WY2025 is approximately 19,300 ac-feet. Most STA cells are at or near target stage. STA-1E Eastern Flow-way is offline for re-hydration and vegetation establishment following erosion repair. Operational restrictions are in effect in STA-1E Western Flow-way, STA-2 Flow-ways 2 and 4, and STA-3/4 Eastern Flow-way for vegetation management activities. An operational restriction is in effect for STA-2 Flowway 5 for construction activities. STA-1W Eastern and Northern Flow-ways and STA-2 Flow-way 1 contain nests of Migratory Bird Treaty Act protected species. This week, if 2008 LORS recommends Lake releases to the WCAs and conditions allow, releases will be sent to STA-2, STA-3/4, or STA-5/6.

Over the last few weeks rates of stage change were generally favorable for wading bird foraging and dry season Everglades ecology. Stages decreased on average in Taylor Slough but depths remain above historical estimates for this time of year. Average salinity increased in Florida Bay last week, however conditions are below historical estimates and the 25th percentile for this time of year. Florida Bay MFL metrics remain well below thresholds of harm. Wading bird foraging and nesting numbers remain below average in the WCAs but drier weather has meant a recent increase in foraging and nesting. White Ibis continue to nest in numbers at Alley North, within the Refuge and ENP, with an additional 5K nests initiated very recently. Wood Storks continue to initiate more nesting in WCA-3A and BCNP. These nests are likely doomed to fail as there is not enough time to fledge chicks before the wet season rains begin.

Biscayne Bay
Total inflow to Biscayne Bay averaged 70 cfs, and the previous 30-day mean inflow averaged 176 cfs. Salinity data were not available for BBCW8 and BBCW10, but the average daily salinities for these stations were 29.2 and 18.9 on April 30, 2024, which are both within the ideal salinity range for estuarine organisms in this region (salinity less than 35). Data were provided by Biscayne National Park.