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Each year, millions of visitors walk across two concrete arch bridges at Niagara Falls.

Those bridges were built between 1900 and 1901, and the New York State Office of Parks, Recreation and Historic Preservation has proposed that they be replaced.

Replacing the bridges that connect Prospect Point on the mainland to Green Island and Goat Island could require shutting down the American Falls, the New York agency said in an assessment. 

According to the assessment, in order to demolish the bridges, the river channel first has to be dewatered because the piers and abutments for the new bridges need to be built on dry land.

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A temporary cofferdam will be built to accomplish the dewatering.

Some are concerned that shutting down the falls will have a negative effect on tourism. According to CNN, the area attracts more than 20 million tourists a year. 

The assessment said the following about the impact on tourism: “Dewatering is expected initially be a tourism draw (a once-in-a-lifetime opportunity to see the falls and river channel without water), but after some period of time could negatively impact park attendance, particularly during the summer tourist season.”

But Niagara Tourism & Convention Corporation CEO John Percy told CNN that the dewatering is "an exciting -- even an enormous -- marketing opportunity for us."

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Others tend to see the glass as half empty.

"People won't be able to come and see it, and they won't be able to see how pretty it is,” Kalie Pries told CNN affiliate WKBW. “Some people say it's spiritual when they come and see it. But I guess they have to do what they have to do." 

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