SFWMD: Weekly Environmental Conditions Report
South Florida - Thursday October 06, 2022: The South Florida Water Management District (SFWMD) provides the following Environmental Conditions Report dated October 5th. It refers to conditions in and along SFWMD managed lakes and rivers before and after Hurricane Ian.
Weather Conditions and Forecast
As of Wednesday, October 5, a cold front will be positioned over Lake Okeechobee, with light frontal rains possible to the lower east coast. A farther southward progression of the front on Thursday will limit any form of rainfall to areas near and over the Florida Keys. On Saturday, a tropical wave traveling westward through the Caribbean will cause moisture levels to rebound somewhat, increasing the amount of rainfall over the lower east coast. With moisture levels gradually increasing throughout the day and a breezy NE wind present, light-to-moderate shower activity could be possible throughout most of the day, with the heaviest shower activity limited to the immediate coast. A continued increase in moisture levels on Sunday and Monday could support moderate-to-heavy storms, mainly along the immediate coast, with all day rains likely. Below average rainfall is expected for the 7-day period ending next Tuesday morning. Continued below average rainfall is possible for the week 2 period ending the morning of 18 October.
Hurricane Ian passed over the Kissimmee Basin on September 28-29, 2022, bringing considerable rainfall that raised water levels in East Lake Toho (S-59), Lake Toho (S-61) and KCH (S-65) further above their respective regulation schedules; discharge at their outlet structures is being adjusted to bring stage in each lake back to its respective regulation schedule. S-65A discharge was increased to 10,000 cfs to control a rainfall-driven stage rise in Pool A. With S-65A discharge continuing to rise above bankfull, water depth on the Kissimmee River floodplain rose to a mean depth of 4.11 feet on October 2, 2022. The average concentration of dissolved oxygen in the Kissimmee River declined from 0.3 mg/L to 2.5 mg/L as Hurricane Ian passed over the basin and then decreased to 0.7 mg/L, well below the potentially lethal level for largemouth bass of 1.0 mg/L.
Lake Okeechobee stage was 13.97 feet NGVD on October 2, 2022, with water levels 0.86 feet higher than previous week and 1.40 feet higher than a month ago. Lake stage was in the Base Flow band and in the ecological envelope. Average daily inflows (excluding rainfall) increased from the previous week. No outflows (excluding evapotranspiration) were reported last week. Pumping into the lake occurred at S-2, S-3 and S-4 pumping stations. The most recent satellite image (October 3, 2022) from NOAA’s Harmful Algal Bloom Monitoring System showed that bloom potential was moderate in the western and northwestern parts of the lake. The bloom potential increased in those regions since the previous week. Microcystins were not detected in the water during the September 19-21 routine survey. Chlorophyll a exceeded 40 μg/L (Lake-wide bloom threshold) at 28% of the sites, with the highest value (77.1 μg/L) recorded at the KISSR0.0 location. Communities at 84% of the sites were mixed, 9% were dominated by Microcystis aeruginosa, 3% were dominated by Planktolyngbya limnetica, and the remaining 3% by a mix of M. aeruginosa/M. wesenbergii.
Total inflow to the St. Lucie Estuary averaged 7,066 cfs over the past week with no flow coming from Lake Okeechobee. Mean salinities decreased then quickly increased again at all sites over the past week. Salinity in the middle estuary decreased into the damaging range (10-25) for adult eastern oysters.
Our instruments in the Caloosahatchee only worked for two days this week and stopped working as Hurricane Ian’s storm surge began. The following statements are only based on the two days of data that were available. Total inflow to the Caloosahatchee Estuary averaged 10,950 cfs over the past week with no flow coming from Lake Okeechobee. Mean surface salinities remained the same at S-79, I-75 and 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 Shell Point and Sanibel, and in the damaging range at Cape Coral (<5).
Stormwater Treatment Areas
For the week ending Sunday, September 25, 2022, no Lake Okeechobee water was delivered to the FEBs/STAs. The total amount of Lake releases sent to the FEBs/STAs in WY2023 (since May 1, 2022) is approximately 12,500 ac-feet. The total amount of inflows to the STAs in WY2023 is approximately 733,000 ac-feet. STA cells are above target stage. STA-1E Western Flow-way is offline for post-construction vegetation grow in, STA-3/4 Eastern Flow-way is offline for vegetation rehabilitation/drawdown, and STA-2 Flow-way 2 is offline for construction activities. Operational restrictions are in effect in STA-1E Central and Eastern Flow-ways, STA-1W Eastern, Western, and Northern Flow-ways, and STA-2 Flow-ways 3 and 4 for vegetation management activities. This week, there is no capacity for Lake releases in the STAs.
Rates of stage change were generally “fair” as rapidly rising water depths have some negative ecological impacts on the ecology of the Everglades. Depths recovered to near average stages for this time of year in WCA-3A North after a very rapid ascension over the last two weeks but given the below average conditions in that region pre-storm, that increased ascension rate provided depths that may have been a lifeline to WCA-3A North. Taylor slough stages rose last week and are above average depths for this time of the year. Salinities fell last week and only the eastern region of the Bay remains above the inter quartile range in all regions of Florida Bay and dropped from 8 to 7 above the bay-wide average for this time of year and have climbed from post storm lows in areas without significant rainfall or inflow.
Total inflow to Biscayne Bay averaged 3,374 cfs and the previous 30-day mean inflow averaged 1,368 cfs. The seven-day mean salinity was 26.2 at BBCW8 and 21.6 at BBCW10, both below the preferred maximum salinity of 35. Salinity data provided as a courtesy by Biscayne National Park.
SEE the latest update from SFWMD Executive Director Drew Bartlett HERE:
On October 2, 2022, lake stages were 60.7 feet NGVD (3.7 feet above schedule) in East Lake Toho, 56.6 feet NGVD (2.6 feet above schedule) in Lake Toho, and 54.2 feet NGVD (2.7 feet above schedule) in Lakes Kissimmee-Cypress-Hatchineha (KCH) (Table KB-1, Figures KB-1-3).
On October 2, 2022, average daily discharge was 11,000 cfs at S-65 and to 10,000 cfs at S-65A to manage rainfall-driven rising water levels in KCH and Pool A, respectively. Average daily discharge from the Kissimmee River was 9,600 cfs at S-65D and 9,300 cfs at S-65E (Table KB-2). Headwater stages were 50.6 feet NGVD at S-65A and 28.7 feet NGVD at S-65D on October 2, 2022. As S-65A discharge and local runoff increased to the Kissimmee River, mean river channel stage increased by 1.13 feet (Figure KB-4) and water depth on the Kissimmee River floodplain rose to a mean depth of 4.11 feet on October 2, 2022 (Figure KB-5). The average concentration of dissolved oxygen in the Kissimmee River increased from 0.3 mg/L to 2.5 mg/L as Hurricane Ian passed over the basin and then decreased to 0.7 mg/L on October 2, 2022 (Table KB-2, Figure KB-6).
Water Management Recommendations
Per the IS-14-50.0 discharge plan, adjust S-65 discharge to maintain a minimum flow of at least 1,400 cfs at S-65A to the Kissimmee River. Note general guidance for discharge and maximum rates of change in discharge (Figure KB-7).
Actions being taken by the SFWMD to relieve flooding:
- Continuing to work in partnership with Osceola County and Orange County to reduce flows of water into the regional lake system and provide relief to impacted communities.
- Some regional lakes appear to have reached their peak. This means that District operations will move water out of those lake systems and begin lowering those lake levels.
- Deploying additional high volume pumps at strategic locations and many more pumps are being staged and getting ready for operation.
- Continuing to work with Lee County to remove debris out of the drainage system.
- Continuing to coordinate with our local, state and federal partners including FEMA to support local recovery efforts.
- Re-opened six navigational boat locks in Glades, Hendry, Martin and Okeechobee counties.
- Using water control structures and other navigational locks at full capacity to move water away from communities.
- Re-opened SFWMD-Managed Lands in Hendry, St. Lucie, Martin, Palm Beach, Broward and Miami-Dade Counties today at 5:00 pm. All other SFWMD-Managed Lands will remain closed for safety purposes.
- Keeping the SFWMD's Emergency Operations Center at Level 1, Full Activation.
Residents are reminded to avoid floodwaters and pay attention to their County Emergency Operations Center. Boaters are encouraged to exercise caution when navigating waterways and avoid creating a wake that could impact homes and businesses.
SFWMD will continue to keep the public informed on its emergency operations.