Lake Okeechobee System Operating Manual (LOSOM) (O&M)

May 2024


Lake Okeechobee System Operating Manual (LOSOM)
Operations and Maintenance (O&M)
Congressional Districts: 8, 9, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28


The U.S. Army Corps of Engineers (USACE) is completing re-evaluation of Lake Okeechobee operations to incorporate benefits provided by the completion of Herbert Hoover Dike (HHD) rehabilitation in January 2023. The goal of the Lake Okeechobee System Operating Manual (LOSOM) effort is to incorporate flexibility in Lake Okeechobee operations, while balancing the congressionally authorized project purposes for flood control, water supply for agricultural, municipal, and environmental uses, recreation, navigation, and enhancement of fish and wildlife.

Section 1106 of the 2018 Water Resources Development Act states, “The Secretary shall expedite completion of the Lake Okeechobee regulation schedule to coincide with completion of the Herbert Hoover Dike project and may include all relevant aspects of the Comprehensive Everglades Restoration Plan described in section 601 of the Water Resources Development Act of 2000 (114 Stat. 2680).” Thus, the LOSOM effort also considers the future Comprehensive Everglades Restoration Plan (CERP) infrastructure that will provide additional flexibility for lake operation, but LOSOM is not a CERP effort. Future evaluation of Lake Okeechobee operations under CERP will be triggered by CERP storage infrastructure north and south of the lake.

The result of the LOSOM effort will be a new system operating manual (SOM) for Lake Okeechobee focused on beneficial use of available water and the accompanying National Environmental Policy Act (NEPA) Environmental Impact Statement (EIS).


Allocation for FY24 $0
President’s Budget FY25 $0


South Florida Water Management District (SFWMD)
3301 Gun Club Road
West Palm Beach, Florida  33406


Extensive stakeholder coordination has been the backbone of LOSOM from via 10 NEPA scoping meetings conducted throughout February and March 2019 through the alternative development and evaluation phases in 2020 and 2021, during development of operating criteria in spring 2022, and during review of the Draft EIS released in July 2022. This engagement ensured varied perspectives on balancing the project purposes were represented and informed the selection of the LOSOM plan.

Due to delays in conclusion of formal ESA consultation with NMFS starting in February 2023, the release of the LOSOM Final EIS and WCP has been on-hold. The NMFS Biological Opinion (BO) assigns legal “take” responsibility to a consulting federal agency for effects on a listed species that are not caused by the consulting agency’s proposed discretionary action, but that are instead caused by actions and factors within the “environmental baseline.” NMFS’ environmental baseline in the BO is not consistent with the analysis in the Corps’ Biological Assessment, the environmental baseline in the U.S. Fish and Wildlife Service BO, nor the Memorandum between the Department of the Army (Civil Works) and the National Oceanic and Atmospheric Administration dated January 5, 2022, for establishing the environmental baseline for analysis. Consultation has concluded as of March 2024 with notification from the ASA (CW) to NOAA Assistant Administrator of Fisheries that the USACE views being as fully compliant with the ESA in implementing LOSOM without the BO based on the documented consultation history, an appropriate environmental baseline, and USACE authorities and limited discretion of the USACE. The USACE will move forward with finalizing the EIS and water control plan with a target for the Record of Decision for the new SOM in July2024.

The recommended lake regulation schedule and operating criteria that make up the WCP remain unchanged from the Draft EIS released in July 2022. Performance improvement of LOSOM operations over LORS08 is expected as follows:

  • Lake O will be more dynamic under LOSOM meaning stages will fluctuate throughout the Zone D to take advantage of storage when it is needed to keep water in the system and to provide valuable water for the environment and water supply.
  • LOSOM has a large operational zone “Zone D”, where the lake will spend most of the time (nearly 80% of the period of simulation [POS]), that provides benefits to the whole system.
  • LOSOM will eliminate lake releases to the St. Lucie under normal conditions, sending zero lake water to the east 95% of the time during the POS. Under LORS08, releases east were at zero only 37% of the time and the flows could reach 1,800 cubic feet per second frequently.
  • LOSOM will eliminate releases to the Caloosahatchee River from Lake O that could contribute to estuary stress in Zone D and provide lake flows that are compatible with estuarine ecology as recommended by the most recent science.

  • LOSOM will perform better for water supply for the Seminole Tribe of Florida, the Lake Okeechobee Service Area, and the Lower East Coast Service Areas than LORS08 in the POS. 

  • LOSOM specifically considers water quality, especially blue green algae during the water management decision making process.

  • LOSOM will increase flows south to the Central Everglades to an average annual of 200,000 acre-feet per year and allow the release of water south all the way to the water shortage management line in coordination with the SFWMD unlike LORS 08 which stopped releases south at higher lake elevations.

  • LOSOM will maintain the safety of the millions of people in South Florida who rely on the Herbert Hoover Dike for flood risk management.

  • LOSOM will reduce damaging dry downs on Lake O.

Click to see full-sized map of project area