Location: On the Safe Harbor Dam fishing platform, find the high water level markers on the dam wall. 39°55’29.4″N 76°23’21.6″W.
History Brief: At full load, 30 million gallons of water per minute pass through the turbines at Safe Harbor. With its record-setting rainfall for Pennsylvania in 24 hours, Hurricane Agnes changed that to 931,000 cubic feet per second, about five times the flow over Niagara Falls.
Clue: Record the height of the Susquehanna River at Safe Harbor on June 24, 1972.
Fun Fact: Here’s a fun fact about those “high water levels.” It’s not the depth of the water to the river bottom but the height of the water above sea level.
Rest of the Story: Safe Harbor Dam, erected in 1931 and constructed of concrete and steel, is 62 feet high, 4,846 feet long, and has 32 spillway gates. The pond behind the dam, called Lake Clarke, is 10 miles long and has 7.360 acres of water.
At full load, 30 million gallons of water per minute pass through the turbines. In the aftermath of Hurricane Agnes, the water flow at Safe Harbor measured 931,000 cubic feet per second, about five times the average flow over Niagara Falls. On an average June day, it is about 30,000 CFS.