Newspaper article The Record (Bergen County, NJ)

Dams on Passaic Tributaries Pose Risk

Newspaper article The Record (Bergen County, NJ)

Dams on Passaic Tributaries Pose Risk

Article excerpt

It's the day after a storm. The sky is clear, and you are in a kayak on the Ramapo River, enjoying the swift current generated by the prior day's rainfall. Then you plunge over a 6-foot dam you hadn't seen.

You are thrown from your craft, and sucked into a hydraulic juggernaut that you can't possibly swim away from. You're wearing a life vest, but it's not helping.You go under.

That's a scenario the Pequannock River Coalition wants to prevent at two old feeder dams on tributaries of the Passaic River.

The coalition, in its last act before shutting down at year's end, sent letters to state, county and town officials urging that - at a minimum - warning signs be placed upstream and downstream of the dams to alert canoeists and kayakers. One dam is on the Ramapo River in Wayne and Pequannock, and the other is on the Pequannock River just east of the North Jersey Equestrian Center.

"From upstream the dams look like an infinity pool - you wouldn't even notice them," said Ross Kushner, the coalition's former executive director. "But they create unusual hydraulics that are dangerous. Somebody has to take ownership of this problem and do something."

To demonstrate the hydraulic power, Kushner dropped a tree branch into the Ramapo this week. The branch slid over the dam and disappeared into the roiling water for about 10 seconds, then shot straight into the air.

There are no warning signs near the dams now. In the past, Wayne placed signs near a short trail that leads to one of the dams; Pequannock plans to provide safety information at kiosks as part of a river trail project.

Because neither dam is on lots identified on tax maps, the state Department of Environmental Protection has assumed responsibility for them. The agency studied whether to remove the dams several years ago to reduce flooding in nearby towns, but it concluded that removal would not have any impact on flooding, and decided to keep the dams in place.

DEP spokesman Larry Hajna said that, aside from the coalition letter, the agency has not received complaints about the dams.

The dams, each about 6 to 7 feet high and extending about 270 feet across the rivers, are a type known as low-head dams.

"Upstream, as the water gets closer to the dam, it squeezes into a smaller space as it goes over the crest, and the water velocity increases, so if you're kayaking you might not have time to escape before being pulled over the dam," said Bruce Tschantz, a safety expert at the University of Tennessee on dams.

"Once you go over, you can get tangled in the rotation circuit, like a washing machine," Tschantz said. "There's an intense velocity and hydraulic jump that create very violent conditions."

In addition, the water at the base of the dam gets aerated, which reduces the buoyancy of life jackets by as much as 30 percent, he said.

The hydraulic power strengthens as stream flow increases, so children who play around such a dam when the flow is low might not realize the danger of playing there when the flow is stronger, Tschantz said.

There are nearly 400 documented cases since 1960 of people drowning in the United States after being sucked into the hydraulic rotation at the base of low-head dams, according to Tschantz's research. …

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