Good Question: Why isn't a Local Dam Preventing Flooding?

May 30, 2017 06:28 AM

Several viewers asked Pat Taney if the Mt. Morris Dam is doing enough to prevent flooding along Lake Ontario for this week's Good Question segment.

Hundreds of homeowners are dealing with a nightmare along Lake Ontario. Homes are flooded, docks are underwater and millions of dollars in damage are being reported.

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Several miles south, down the Genesee River, sits the Mt. Morris Dam in Livingston County.

"This dam is over 1,028 feet across 245 feet tall and it can hold 302,000 acre feet of water above it," said Dam Manager Steve Winslow, who is with the Army Corps of Engineers.

But when we visited the dam, its storage lake - where water is held back from going down the Genesee River and eventually into the lake - was not anywhere near full or at capacity.

Taney: That looks very empty and to think there are gallons and gallons of water flooding people's homes right now downstream along the lake, how do you respond to that?

Winslow: First and foremost this dam was never built to protect the lakeshore.

The dam, built in the 1950's, was constructed to prevent flooding in communities along the Genesee River, including the City of Rochester.

"Our main purpose is really to help protect the city and all of the area in between from flooding that happens on the river itself not the lakeshore."

The dam has already had to close gates this spring to prevent flooding along the river. Winslow says closing the dam did not and would not impact flooding along the lake, again he says that's not the dam's purpose.

Winslow: Let me give you a scenario if we filled the full extent of our storage capacity at the dam and then we were able to pick up all of that water at once and dump it directly into Lake Ontario, it would raise the lake's levels by one and a half centimeters. It's nowhere near big enough to control water depths on Lake Ontario.

The dam also can't stay at capacity and hold water back longer. It needs to release periodically to prepare for another rain event.

"Let's say we did hold back the water and stay at capacity. Then we get another major rain event, water would spill over and we're talking the potential for catastrophic flooding for communities along the Genesee River, including the City of Rochester," Winslow said.

Since it opened in the 1950's, the dam has prevented billions of dollars in flood damage.


Pat Taney

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