Good Question: Why Can’t We Open Dams To Prevent Floods?

By Jason DeRusha, WCCO-TV

— It’s the one weather phenomenon we know about months in advance. The National Weather Service is forecasting near record flood levels throughout Minnesota. So, why doesn’t the Army Corps of Engineers open up the dams and let the flood water flow downstream?

“Actually there’s two good answers to that,” said Scott Bratten, hydrologic technician for the St. Paul District of the Army Corps of Engineers.

Bratten deals with water levels and the locks and dams that the Army Corps controls.

“The first is it’s against the law,” said Bratten.

In 1934, Congress passed the Anti-Drawdown Law. It forces to army corps to maintain the system of locks and dams as if barges were navigating the river year-round.

“This anti-drawdown law was to protect the habitat and the environment,” he said.

However, even if there were no law, opening the dams wouldn’t make a difference with flooding.

“None whatsoever,” said Bratten.

The system of dams essentially creates pools along the river, deep enough for barges to travel along. The dams have gates underwater that can be opened and closed, to help keep the water at the right depth.

“These pools are small. It’s like steps on the river, creating little pools,” said Bratten.

The biggest pool is the one created downstream of lock and dam 4 in Red Wing. It’s just 44 miles long, which isn’t much considering the volume of water that’s expected during a flood.

“They would be filled within hours during peak levels,” said Bratten, “It just wouldn’t work.”

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