Lake Okeechobee

Lake Okeechobee is the accepted name used in federal and Florida records. This page covers the physical lake—including open water, islands and the littoral marsh inside the managed lake boundary—and its immediate basin setting. It does not use “Okeechobee” to mean the City of Okeechobee, Okeechobee County, the larger inflow watershed, or the cross-Florida Okeechobee Waterway.^[1][2]

The shoreline lies within Glades, Hendry, Martin, Okeechobee and Palm Beach counties, but those administrative divisions do not partition the hydrology. The USGS coordinate above identifies a historical monitoring location in the lake. It is a reproducible point for mapping, not a claim that an irregular, stage-dependent water body has one exact center.^[2][4]

SFWMD reports a 730 mi² (1,891 km²) surface area and a 9 ft (2.7 m) mean depth; USACE describes the lake as approximately 37 mi (60 km) north–south by 30 mi (48 km) east–west. A 2024 USGS report gives about 135 mi (217 km) of shoreline, explicitly including several small islands. Length and shoreline are approximate because bays, marsh edges, islands and stage complicate the perimeter.^[1][3][8]

Not every published area measures the same outline. A federal lake-management manual lists 427,000 acres—about 667 mi² or 1,728 km²—while SFWMD uses 730 mi². The cited summaries do not attach a common water stage or polygon definition, so the 63 mi² difference should not be presented as measured expansion or contraction. The larger figure is retained as the current SFWMD summary; the smaller figure remains a documented scientific convention.^[1][10]

Depth is more variable than the lakebed. In September–October 2001, USGS mapped the bed with 519,383 single-beam soundings on north–south lines generally 1,000 m apart, with observations about every 3 m along each line. The survey used WGS84 horizontal control and NAVD 88 elevations and omitted eastern water too shallow for safe boat work. It is therefore a dated elevation survey of most of the floor—not a timeless chart of water depth.^[4]

The lake occupies the Kissimmee–Okeechobee lowland, roughly 30 mi (48 km) west of the Atlantic coast and 60 mi (97 km) east of Florida's Gulf coast. The Kissimmee River enters the north side; Taylor Creek–Nubbin Slough reaches the northeast; Fisheating Creek enters the western littoral zone. South of the lake, the Everglades Agricultural Area occupies former wetland between the lake and the remaining Water Conservation Areas and Everglades farther south.^[3][7][8]

Relief is measured in feet rather than hundreds of metres. Sandy ridges and better-drained plains flank the wider lowland, but no steep rim encloses the water. This low gradient explains both the broad pre-drainage overflow southward and the ease with which canals, levees and pumps later redirected flow across basin boundaries.^[7][8]

The depression is older than the present freshwater lake. USGS regional geology interprets it as a slight low that originated on a late-Pleistocene shallow-marine surface; solution of near-surface limestone and marl may have deepened parts of it, but Okeechobee is not a single collapsed sinkhole. A later synthesis places emergence of the lake landform at about 6,300 years ago and attainment of broadly modern form around 4,000 years ago. Those are regional geologic estimates, not a single construction date for the basin.^[5][6]

The floor is not a uniform saucer. Fine organic mud occupies much of the deeper north-central and eastern open-water basin. A broad sand-and-shell belt lies west of it; peat and marsh sediments dominate shallow southern and western sectors; and a low, east–west limestone or marl ridge crosses the southern basin. SFWMD describes the ridge as about 1 mi (1.6 km) inside parts of the south and west shore. At lower stages it restricts exchange between central turbid water and clearer nearshore water; at higher stages water passes over it more readily.^[6][7]

A 2005–2006 SFWMD planning document mapped about 98,000 acres (153 mi²; 397 km²) of littoral marsh inside the levee system. That is a management-era estimate, not a fixed natural shoreline: inundated area and the boundary between emergent marsh, submerged vegetation and open water shift with stage and disturbance.^[7]

The Kissimmee River is the dominant inflow. A USACE basin overview attributes more than 60% of inflowing water to the Kissimmee and about 9% to Fisheating Creek; the percentages are long-term summary shares, not values expected in every year. Lake Istokpoga drainage, Taylor Creek–Nubbin Slough, smaller canals and tributaries, direct rain, and groundwater exchange complete a water budget that varies with storms, drought and operations.^[8][12]

Before canal construction, high stages overtopped the low southern rim and fed the Everglades by broad sheet flow. There was no natural surface connection to either coast: the Caloosahatchee connection was excavated in the late nineteenth century, and the St. Lucie Canal opened an eastern route in the twentieth. Today the Caloosahatchee River/C-43 to the west and St. Lucie Canal/C-44 to the east are the principal controlled coastal outlets; southward deliveries use canals and water-control areas rather than the former unrestricted overflow.^[7][8]

The Herbert Hoover Dike system includes about 143 mi (230 km) of levee plus culverts, gates and other structures. It defines much of the modern outer lake edge, although Fisheating Creek enters through a gap between tie-back levees. Since 12 August 2024, releases have been governed by the Lake Okeechobee System Operating Manual (LOSOM), which replaced the 2008 schedule; this page does not turn a changing operating zone or current stage into a permanent geographic statistic.^[9]

Lake stage is the elevation of the water surface above a vertical datum; depth is the distance from that surface to the bed. They cannot be substituted. USACE notes that, for the regulation schedule, 12.5 ft NGVD 29 corresponds to 11.25 ft NAVD 88, while conversions at individual gauges vary. SFWMD gauges use NAVD 88, whereas some USACE products continue to report NGVD 29, so every stage value needs its datum.^[9]

With a mean depth near 9 ft and an unobstructed wind fetch approaching 37 mi, Okeechobee is polymictic: it circulates many times rather than maintaining a summer-long deep cold layer. Calm, sunny weather can produce short-lived daily stratification, but stronger wind restores vertical mixing. The same wind stress drives currents and waves across the shallow floor, resuspending fine mud and changing turbidity without changing the underlying geologic basin.^[10]

The National Weather Service defines south Florida's rainy season as approximately 15 May–15 October, when about 70% of annual rain falls. Its 1991–2020 wet-season normal for Moore Haven on the southwest shore is 33.13 in (842 mm). That station value orients the lake's seasonal setting; it is not a lake-wide precipitation average. Sea-breeze and lake-breeze boundaries help locate daily thunderstorms, while tropical disturbances can deliver basin-wide rain and strong winds late in the season.^[11]

Evaporation is a measured major loss, not merely a dry-season assumption. At the central LZ40 platform, a USGS Bowen-ratio energy-budget study measured mean annual open-water evaporation of 1,825 mm (71.9 in) for 2013–2016; annual values ranged from 1,760 to 1,890 mm. The authors link the high rate to frequent clear skies over the lake interior: water heats more slowly than surrounding land, suppressing some daytime convective cloud formation. Summer solar energy raised the seasonal rate, while windy, dry-air passages behind winter cold fronts produced short evaporation spikes.^[12]

At regional scale, water descends from the Upper Kissimmee chain of lakes through the Kissimmee River to Okeechobee. Historically, surplus water then crossed the southern rim into the Everglades and ultimately Florida Bay and Gulf outlets. The modern system adds reversible structures, storage areas and east–west connections, so the direction of flow at an individual canal can depend on lake stage and surrounding basin conditions. “Kissimmee to Florida Bay” describes the system's geographic spine, not an uninterrupted present-day river channel.^[1][8]

Compare Okeechobee's shallow mixing and stage-sensitive margins through the lake hub, or place its low ridges, marsh shelves and sediment zones in the terrain index.

1. South Florida Water Management District, “Lake Okeechobee” (accessed 30 August 2026). Source for the agency's 730 mi² area, 9 ft mean depth, accepted name, basin role and Greater Everglades setting.
2. U.S. Geological Survey, monitoring location 02276400, “Lake Okeechobee, FL” (accessed 30 August 2026). Source for the 26.9503342° N, 80.8331167° W WGS84 monitoring-location reference and hydrologic unit 03090201.
3. U.S. Geological Survey, Societal Benefits of Cyanobacteria Harmful Algal Bloom Management in Lake Okeechobee in Florida, Scientific Investigations Report 2024–5091 (2024), “Site and Event Description.” Source for approximate coast distances and the 135 mi shoreline figure including small islands.
4. Hansen, M. E., DeWitt, N. T. & Reynolds, B. J., U.S. Geological Survey, Archive of Bathymetry Data Collected in South Florida from 1995 to 2015, Data Series 1031 (2017), and its Lake Okeechobee project description. Source for 2001 survey coverage, dates, spacing, soundings, control, accuracy and county coverage.
5. Stringfield, V. T., U.S. Geological Survey, Artesian Water in Tertiary Limestone in the Southeastern States, Professional Paper 517 (1966), pp. 86–87. Source for the interpreted late-Pleistocene shallow-marine depression, subdued form and possible near-surface solution contribution.
6. Wang, J. et al., “Legacy Phosphorus in Lake Okeechobee (Florida, USA) Sediments: A Review and New Perspective”, Water 13, 39 (2021). Source for the Holocene age synthesis, underlying formations and mapped mud, sand, peat and rock-bottom history.
7. South Florida Water Management District, 2005–2006 Consolidated Water Supply Plan Support Document, especially pp. 9–17 and 205–207. Source for the 98,000-acre littoral-marsh estimate, physical regions, low relief, historic overflow and current managed setting; and “Lake Okeechobee FAQs” for the southern/western rock ridge and its stage-dependent hydraulic effect.
8. U.S. Army Corps of Engineers, Jacksonville District, “Lake Okeechobee: Following the Flow” (2013; accessed 30 August 2026). Source for approximate dimensions, inflow shares, named tributaries, pre-canal flow, coastal canal history, present outlets and the Fisheating Creek gap.
9. U.S. Army Corps of Engineers, Jacksonville District, “Herbert Hoover Dike FL” fact sheet (May 2025), for levee-system length and structures; Lake Okeechobee vertical-datum notes, for NGVD 29/NAVD 88 distinctions; and LOSOM Record of Decision announcement (13 August 2024), for the operating manual's effective date.
10. Holdren, C., Jones, W. & Taggart, J., Managing Lakes and Reservoirs, 3rd ed., EPA 841-B-01-006 (North American Lake Management Society and Terrene Institute in cooperation with U.S. EPA, 2001), pp. 28–29. Source for the 427,000-acre convention, 8.9 ft mean depth, nearly 37 mi fetch and polymictic classification.
11. NOAA National Weather Service, Miami–South Florida Forecast Office, Rainy Season 2021 Outlook (11 May 2021), pp. 3–4. Source for rainy-season timing, approximate annual-rainfall share, storm controls and the 1991–2020 Moore Haven wet-season normal.
12. Shoemaker, W. B. & Wu, Q., U.S. Geological Survey, Evaporation from the Interior of Lake Okeechobee—A Large Freshwater Lake in Florida, 2013–16, Scientific Investigations Report 2024–5040 (2024). Source for the inflow/outflow inventory, Bowen-ratio method, measured annual evaporation and physical explanation of clear-sky and cold-front effects.