Two Florence, NJ homeowners are being told to evacuate because of a growing risk that the houses could slide into the Delaware River.

Officials in Florence say they told the owners of the home Wednesday that it's unsafe for them to stay overnight. They are being given time to take out their belongings.

Township administrator Richard Brook says he does not expect them to be able to return unless significant repairs can be made.

Erosion has been a problem for several years for some homes in Florence, but a recent rain has created a growing pit and sent a large tree 70 feet below into the river.

Owner Chris O'Dell calls the situation "overwhelming."

The eroded backyard of a Florence home (CBS Philly)

"The county engineer is working closely with municipal officials to determine the many factors that are contributing to the situation and find the best way to remedy it," Burlington County spokesman Eric Arpert said. "The safety of the homeowners is the most important thing."

The O'Dells told NBC 10 that the backyard of their Front Street has been eroding for the past two years but Burlington County was slow to offer help in investigating the cause.

Lynn O'Dell told 6 ABC that a large portion of the home's backyard sunk away, taking several birdhouses with it and separating sections of fencing as well.

The problem accelerated in recent months, threatening two other homes in the neighborhood. Monday's downpours caused the erosion to increase and exposed a possible cause: an old county drain.

Chris O'Dell told CBS Philadelphia township employees) opened a storm sewer in front of his house and found that a cap place on it years ago had broken loose. "This storm water had been running through the pipe into here for we don’t know how long,” O’Dell said.

The O'Dells are concerned they may be forced to evacuate while repairs are made."Every time it rains, I cringe," Lynne O'Dell said.

The couple obtained a county report from 1990 about erosion in the area from a neighbor according to the Times of Trenton. The report says that an old sewer system that dumped its collected water into the river was capped with brick and tar. The Times also reports a claim filed by the couple against the county several weeks ago was denied by an insurance company.

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The Associated Press contributed to this report