The men who dug the Columbia Canal between 1820 and 1824 came over from Ireland on indenture contracts that promised them passage and wages in exchange for their backs. Many of them are buried at St. Peter's Catholic Church four blocks east. They died of cholera, of dysentery, of the malarial summers along the Congaree, and of the simple accumulated brutality of moving a Fall Line's worth of earth with picks and mule carts. The canal they finished - three and a tenth miles long, with four lifting locks descending 34 feet around the rapids where the Broad and Saluda Rivers meet to form the Congaree - made river commerce possible between the upcountry and the Lowcountry for exactly sixteen years before the railroads arrived and made the whole effort obsolete.
South Carolina built it the way states built things in the early nineteenth century: with public subsidy and indentured labor, on a route surveyed to follow a natural ravine between Columbia and the river. The completed channel ran 3.1 miles along the Congaree, from a point between today's Calhoun and Richland Streets down to Granby Landing. North of Senate Street it was twelve feet wide and two and a half feet deep, with an eight-foot towpath along each side. South of Senate Street it widened to eighteen feet and deepened to four. Four lifting locks plus a guard lock handled the 34-foot descent; three waste weirs prevented flooding when storm runoff swelled the system. A diversion dam across the Broad River let boats from the Saluda Canal reach the network. By 1840 the state had stopped subsidizing it. By 1842 the railroads were in Columbia, and within a few years the canal had effectively ceased to carry commerce. During the Civil War its hydraulic power was repurposed to grind grain and make gunpowder for the Confederacy.
In 1888 a new generation of engineers redesigned the canal not for boats but for electricity. The reworked channel started at Gervais Street and extended three and a half miles north, 150 feet wide and ten feet deep - a moving column of water massive enough to spin industrial turbines. The enlarged canal was completed in 1891. The Columbia Mill rose on high ground north of Gervais Street, and when it opened in April 1894 a powerhouse 600 feet away on the canal turned out alternating current to drive the mill's motors. That made Columbia Mill the first textile mill in the world to use AC motors and to generate that power away from the factory floor - a milestone in the long argument between Edison's direct current and Tesla's alternating current that Tesla was on his way to winning. The Columbia Hydro plant at the canal's south end soon powered the city itself and the Columbia streetcar system. The old Columbia Mill building today houses the South Carolina State Museum. The canal still generates.
In September 2008 the St. Columbia division of the Ancient Order of Hibernians dedicated a granite memorial along the canal to the Irish laborers who dug it. Some are named on the stone; most are not. Then, in early October 2015, the same storm system that devastated parts of South Carolina dropped record rainfall on the Congaree watershed and breached the canal. The South Carolina Army National Guard sandbagged it in the immediate aftermath, and federal HUD funds were approved for permanent repair in 2021. As of early 2024 the work was still in planning. Riverfront Park along the canal remains the heart of Columbia's relationship with its rivers - joggers, kayakers, the powerhouse still spinning - but the breach is a reminder that the system the Irish laborers built has been negotiating with the Congaree for two hundred years, and the Congaree always has the last word.
The Columbia Canal lies between 34.02°N, 81.06°W and the southern end near downtown Columbia, running roughly parallel to the Congaree River for about three and a half miles. From the air the canal reads as a narrow straight band of water immediately east of the wider Congaree, with Riverfront Park's tree line along its western edge. The 1891 hydroelectric plant is at the southern end near Gervais Street; the breach point from the 2015 flood is mid-channel. The South Carolina State House is about one mile southeast. Columbia Owens Downtown (KCUB) is three miles southeast; Columbia Metropolitan (KCAE) is seven miles southwest. Best viewing altitudes are 1,500-3,000 feet AGL with the sun behind you.