POWERGRAMS

15 What a difference a year makes. From summer 2016 through fall of last year, Alabama bore the brunt of dry weather. Ordinarily during an Alabama summer, temperatures run high and Mother Nature is stingy with rain. Streams that fill the company's lakes run low, meaning that employees at Alabama Power's 14 hydro facilities work hard to maintain lake levels, in keeping with U.S. Corps of Engineers rules. But Alabama Hydro employees faced the opposite scenario this past summer. In July – when rain is normally scant – much of Alabama received higher than usual rainfall. So much rain came – an additional 17 inches above summer 2016 levels – that several company hydro plants were forced to open spillway gates for several days. Hydro employees scrambled to ensure the extra water made its way downstream without flooding surrounding areas, keeping residents and property safe. Neely Henry Dam Hydro Plant Superintendent Martin Windham was quizzical about July's heavy rains at the Coosa River facility. He said that uncontrolled, heavy rains produce conditions that can quickly raise lake levels. "We had 20 straight days of rain here," Windham said. "We had heavy rain every afternoon. That's something we don't see in July." Surprisingly, storms in the aftermath of September's Hurricane Irma – with heavy rains throughout Alabama for three days, after causing flooding and devastation in Florida – didn't cause lakes to overflow in Alabama. MANAGING RAINS FOR GENERATION AND ENJOYMENT Rainfall is an energy bonus: The water flowing through the hydro turbines produces free generation, said Reservoir Operations Supervisor David Preston, Alabama Control Center - Corporate Headquarters. During 2017, Hydro facilities were able to capture water and restore normal elevations on company reservoirs, which was unusual after the parched summer of 2016. "The rains really picked up in early spring," Preston said. "We had lots of spillway gates open throughout the Alabama Hydro system to manage the rainfall. Our hydro storage projects were still full in late August, which is a good thing. "In comparison to 2015 and 2016, our reservoirs stayed full all summer," he said. "Historically, we tend to be drier in July and August. That continues into the fall. October is our driest month." THE BALANCING ACT There's a delicate balance to maintaining the company's lakes at proper levels – one that Mother Nature sometimes supersedes. At Neely Henry Dam, each of the plant's six spillway gates can deliver 7.6 million gallons per minute to the lake. If the Coosa River is moving toward flood conditions, it is usually evident within two days, Windham said. From Lake Neely Henry, it takes the water roughly 10 to 12 hours to reach Logan Martin Lake, which discharges to Lay Lake, moving downward to Lake Mitchell and on to Lake Bouldin and Lake Jordan. Generally, heavy storms that pass through in 20-30 minutes don't highly affect lake levels. "As far as operations of our hydro facility, you have to stay ahead of it and predict the rain, to an extent," Windham said. "We have a natural water restrictor above us on the Coosa River, the Minnesota Bend, where ENERGY LET IT RAIN HYDRO MANAGES LAKES TO PROTECT RESIDENTS, INCREASE GENERATION by Donna Cope HYDRO MANAGES LAKES TO PROTECT RESIDENTS, INCREASE GENERATION by Donna Cope

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