Heavy rains and river flows help hydroelectric plants generate more electricity, up to a point. Four major dams operate on the lower Susquehanna River. But none of them have the capacity to store the amount of water now rushing down stream and flooding communities along its banks and tributaries.
At the Safe Harbor Dam in Lancaster County 635,000 cubic feet of water per second is flowing downstream. That’s a lot of water for the Susquehanna River. One cubic foot per second is equal to about 450 gallons per minute, so that means 286 million gallons of water a minute. A typical flow for September is just about 6 million gallons. The dam’s maximum capacity is 113,000 cubic feet per second. Safe Harbor’s manager of operations Dan Stambaugh says workers have opened 20 flood gates to control the flow. And the flooding has caused them to shut down two generators.
Stambaugh says the Susquehanna River’s flow rates swing wildly, with the lowest recorded at about 1600 cubic feet per second. He says heavy rains are a good thing for hydroelectric generation, but once it surpasses the dam’s maximum capacity, managing the flow becomes a concern. The highest occurred back in 1972 during Hurricane Agnes, when it reached over a million cubic feet per second. The Safe Harbor Dam began operating in 1931 and at capacity, it can generate 10 million kilowatts of electricity a day.