VALLEY CITY (AP) - Valley City officials thought their sewer system had collapsed under pressure from the Sheyenne River last month. After the flooding subsided and they finally got a camera into the Main Street sewer, they found the problem was on old pipe, not a total collapse of the line.

"It looks like an old overflow pipe we didn't know about gave way and let in the river," Public Works Superintendent Jeff Differding said.

After river water backed up into the basement drains of homes and businesses on April 17, Mayor Mary Lee Nielson ordered non-essential businesses to close and advised people to leave the city until the sewer system was fixed. Hundreds of portable toilets were brought in.

Differding said that was the right move at the time because the city's master sewer lift station was overwhelmed.

"With the river water coming in, we couldn't handle it, he said.

City Administrator Jon Cameron said the sewer system is more than 100 years old. City officials are considering whether to reroute it, at an estimated cost of about $3 million. With the new information, engineers are revising their plans and cost estimates for repairs.

Differding said Thursday the city is using video cameras to do more checking for any sewer damage.

"We're trying to get a good picture of what happened," he said.