Lake Marion Water Level
South Carolina · Santee River
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Water level history
About Lake Marion
Lake Marion is a reservoir on the Santee River in South Carolina, operated by Santee Cooper. It's the largest lake in South Carolina. Its full summer pool sits at 75.5 ft above sea level. Live water levels come from USGS gauge 02171000 and update every 15 to 60 minutes.
Understanding Lake Marion's water level
Lake Marion is not a Corps lake. It belongs to Santee Cooper, the state-owned utility South Carolina created in 1934, and it was the largest New Deal project in the state: a $31 million Public Works Administration grant and loan, described at the time as the most expensive PWA project on the East Coast. Construction began in 1939 after four years of litigation, the Santee River was dammed on 12 November 1941, and the first power reached a Charleston business on 17 February 1942.
The scale of what it took is hard to overstate. Peak employment reached nearly fifteen thousand, most drawn from Depression relief rolls. Forty-two miles of dams and dikes were built, forty-two million cubic yards of earth moved, and around 177,000 acres of swamp and timberland cleared, much of it with handsaws and mule-drawn wagons. Nine hundred and one families were relocated, the majority of them African American, and more than six thousand graves were moved or permanently submerged; a later oral history project recovered the names of over five thousand individuals from unmarked graves.
Operationally, Lake Marion is the controlled pool and Lake Moultrie follows it, the two joined by a seven-and-a-half-mile diversion canal. Santee Cooper publishes a rule curve of just above 72 feet in winter and 75.5 in summer, with a licensed maximum of 76.8, and the gauge record bears out a shallow seasonal cycle of roughly a foot and a half, with medians near 75.4 in spring and around 74 in midwinter. Two other things are worth knowing. The Pinopolis lock lifts boats seventy-five feet and was the highest single-lift lock in the world when built. And by the 1970s the redirected flow was dumping so much sediment into Charleston Harbor that the Corps built a rediversion canal, completed in March 1985, sending about ninety percent of the Santee's flow back to its own river and cutting harbour sediment from ten million to two million cubic yards a year.
Lake Marion — frequently asked
Who owns and operates Lake Marion?
Santee Cooper, the South Carolina Public Service Authority, a state-owned utility created in 1934. It is not a Corps of Engineers lake. The reservoir is part of a federally licensed hydroelectric project that received a new fifty-year licence in January 2023. The Corps does operate one nearby structure, the Cooper River Rediversion Project at St. Stephen, but not the lakes.
What is Lake Marion's normal level?
Santee Cooper publishes a rule curve of just above 72 feet in winter and 75.5 feet in summer, with a licensed maximum of 76.8. In practice the gauge record shows a shallow seasonal cycle of about a foot and a half, with medians near 75.4 feet from April through June easing to around 74 feet in December and January. It is much flatter than a Corps flood-control lake.
How are Lake Marion and Lake Moultrie connected?
By a seven-and-a-half-mile diversion canal. Lake Marion is the controlled pool and Lake Moultrie follows it, with Moultrie's elevation managed by adjusting discharge at St. Stephen rather than by a separate rule curve of its own. Water then passes through Pinopolis Dam, whose lock lifts boats seventy-five feet and was the highest single-lift lock in the world when it was built.
What was flooded to build Lake Marion?
An enormous area of swamp and timberland, around 177,000 acres cleared, much of it by hand with saws and mule-drawn wagons. Nine hundred and one families were relocated, the majority African American, and more than six thousand graves were moved or permanently submerged. A later oral history project recovered the names of over five thousand individuals from unmarked graves.
Why was a rediversion canal built in the 1980s?
Because the project had redirected the Santee's flow into the Cooper River, and by the 1950s to 1970s the resulting sediment was choking Charleston Harbor and forcing expensive annual dredging. Congress authorized a fix in 1968; construction ran from 1978 to March 1985. The rediversion sends about ninety percent of the flow back down the Santee and cut harbour sediment from ten million to two million cubic yards a year.
Why is Lake Marion famous for striped bass?
It is where landlocked striped bass were first documented. After the 1941 impoundment, fish that had run up the Santee seasonally were trapped, and schooling populations appeared by 1950. A study running from 1954 to 1956 examined 408 fish and collected eggs within the reservoir, establishing the first known self-sustaining freshwater striped bass population. They still spawn up the Congaree and Wateree rivers. Hybrids are deliberately not stocked here, to protect that spawning stock.
Other lakes near Lake Marion
- Lake MoultrieSC
- Lake KeoweeSC
- Lake MurraySC
- Lake JocasseeSC
- Richard B. Russell LakeGA/SC
- J. Strom Thurmond Lake (Clarks Hill)GA/SC
See current levels for all 11 South Carolina lakes and reservoirs →
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