River Navigation

The McAlpine Dam is a huge concrete wall whose main function is to control water levels for navigation, while its elongated Z shape also provides water for the hydroelectric station and keeps the fossil beds visible during periods of low water by opening or closing gates in the dam. There are five upper gates under the bridge and four lower gates downriver connecting to the hydroelectric station, each twenty-two feet high and one hundred feet wide, and the dam is over thirty feet high. Its waterfalls, called castellations, allow water to reach the wetland next to the dam even in the driest months, helping maintain plant and animal species. This is the third dam built here; the original was constructed in 1881, with major renovations in the 1920s and in 1961. Behind the dam are the headwaters for the hydroelectric station, where boats are not allowed because of the dangerous current near the turbines. The trees beyond the water are on Shippingport Island, once a busy town and now protected as part of the National Wildlife Conservation Area with access by permit only. Beyond the island is the Louisville and Portland Canal. As early as 1802, the expense and delay of hauling freight around the falls led to several proposed solutions. The Louisville and Portland Canal was begun in 1825, and the first boat passed through in 1830. Originally the canal was 1.9 miles long, sixty-four feet wide, and had a total lift of twenty-six feet with a three-flight lock system. Renovations over the years produced a canal five hundred feet wide and a one hundred ten-foot by one thousand two hundred-foot lock chamber with a lift of thirty-seven feet, and construction is underway on a second one hundred ten-foot by one thousand two hundred-foot chamber to facilitate current and future commercial traffic. According to the U.S. Commerce Department, the Ohio River carries forty percent of the commercial water traffic in the continental U.S. In 2000, 55.8 million tons of products worth more than $12 billion passed through the canal, with coal, petroleum, grain, chemicals, iron, and steel making up most of the tonnage. The U.S. Army Corps of Engineers operates and maintains the McAlpine Locks and Dam.

Clarksville, Indiana · United States