Monument to the power of a river Dam: Conowingo Dam in northeast Maryland, combining old and modern equipment, generates electricity for more than 1.5 million residents


It straddles two counties, a mountain of steel and concrete nearly a mile long and more than 100 feet high, blending into the Susquehanna River as it transforms the river's flow into electricity.

The exterior of the Conowingo Hydroelectric Station and Dam, nearly 70 years old, is an integral part of the landscape of Harford and Cecil counties. It draws anglers and bird-watchers to its teeming reservoir and tourists to the torrent that spills below the structure.

But, deep inside, the dam has a secret life of its own.

From "Turbine Hall," where 11 huge turbines hum with the sound of churning water wheels, to the dank inspection tunnel below a 90-foot spillway, workers scurry behind a wall of water. Black cast-iron machinery remains from the 1920s, and scarred walls provide grim reminders of disastrous floods.

"It's a full-time job keeping this place together," says Glenn W. Gaskill, operations supervisor for the dam, which has 65 operational employees. "There's a lot of upkeep and a lot of work that goes into making this happen."

Conowingo - a Native American word meaning "at the rapids" - cost $52 million and was the brainchild of William C.L. Eglin, chief engineer and vice president of Philadelphia Electric Co.

The first of what would become 435,000 cubic yards of concrete was poured in 1926, and the huge construction project quickly transformed the village of Conowingo (pop. 200) into a boom town of 3,800 workers in temporary dormitories along the river. When it opened March 1, 1928, the Conowingo Dam was one of the largest hydroelectric plants in the nation.

Connecting Harford and Cecil counties 40 miles from Baltimore, the dam forms part of U.S. 1 and stretches 4,648 feet through a rural area framed by trees and rocky shores. Behind it is the Susquehanna and a 14-mile lake that was formed by the dam and has flooded the area on occasion.

The heart of the dam is Turbine Hall.

Here, amid a loud, steady hum, millions of cubic feet of water rush through propeller-like turbines encased in huge, rounded green housings. A smaller, black, cast-iron in-house power unit from 1928 sits near the fiber-optic controls on a main generator.

The electricity travels by wire to a transformer above the turbines, where the current is stepped up to high voltage and sent out over wires from the plant's roof - enough power for more than 1.5 million residents in Maryland, Pennsylvania, Delaware and New Jersey.

River flow, water temperature and generators are regulated from a room 50 feet above Turbine Hall. If the hall is the dam's heart, the control room is the nerve center.

The room is dominated by a bank of gauges and equipment from the 1920s and 1960s, which sit side by side with Macintosh computers on a raised platform.

The control room is staffed 24 hours a day with operators who work eight-hour shifts and keep close watch on the equipment. A small bathroom just off the control room ensures that the operators are never far from their posts.

One recent day, Guy Clardy, a control-room operator for 20 years, walked by the black panel of levers and switches - all original and all still working - and took his place at the computers. His eyes were in constant motion, monitoring the flow levels and the amount of energy being produced.

Clardy said he enjoys seeing modern technology working with old-fashioned equipment.

"The people that engineered this dam were more in tune with nature than industry is today, and they built things much sturdier," Clardy said. "To have units that have been working since 1928 is a testament to that."

But nature is not always kind to those living in the shadow of the dam.

On Jan. 20, 1996, nearly 100 Port Deposit residents were evacuated after chunks of ice and a quick thaw forced dam operators to open 39 floodgates, sending floodwaters into the town. The floodwaters were 5 feet deep, Port Deposit officials said at the time.

Employees at the dam worked around the clock, as blocks of ice from the thawing Susquehanna slammed into the dam and huge amounts of debris clogged the dam's filter screens.

It was the most serious flooding since June 22, 1972, when Tropical Storm Agnes forced all 50 of the floodgates to be opened for the first time since 1936. Residents of Havre de Grace and Port Deposit were evacuated in the 1972 flood.

Kim Dooling, the 30-year-old manager at Union Hotel Restaurant in Port Deposit, remembers the 1972 and 1996 floods.

"When Agnes hit, I was real little, but I remember my mother talking about how the Amish came down to help and about driving down [Route] 222 and seeing appliances up in the trees," Dooling said. "When the flood happened last year, my husband and I had been in our newly renovated house for only three weeks."

Last year, dam officials and residents downstream were caught by surprise when a quick melt resulted in a raging river.

"It sounded like a thousand freight trains coming," said Gaskill, the operations supervisor. "It was amazing."

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