RALEIGH (Reuters) - Residents of Georgetown County, South Carolina, where five rivers flow into the ocean, were preparing on Friday for a deluge of water in the aftermath of Hurricane Florence, which has killed at least 40 people.

The county of 60,000 people, on the Atlantic coast between Myrtle Beach and Charleston, is one of several areas in the Carolinas waiting anxiously as rivers start to crest, a week after Florence dumped some three feet of rain on the region.

Flooding could begin early next week, officials said during a community meeting on Thursday, as water continues to drain into rivers and reservoirs across North and South Carolina.

The city of Georgetown on Friday was handing out 15,000 sandbags as the county developed plans to evacuate residents.

“Please heed the warnings,” Sheriff Lane Cribb said. “Protecting lives and property will be our goal ... You better pray.”

Thirty-one deaths have been attributed to the storm in North Carolina, eight in South Carolina and one in Virginia.

More than three dozen flood gauges in North and South Carolina showed flooding, according to the National Weather Service.

In Bladen County, North Carolina, around 100 people and 33 animals were rescued “in a dangerous operation in the middle of the night” after a dam burst, Governor Roy Cooper said in a twitter post on Friday. Blackhawk helicopters were used to pluck many of them to safety.

Some 4,700 people across North Carolina have been rescued by boat or helicopter since the storm made landfall, twice as many as in Hurricane Matthew two years ago, according to state officials. About 10,000 remained in shelters.

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The coastal city of Wilmington, North Carolina, remained mostly cut off by floodwaters on Friday,

Some 650 roads remained closed, the state’s department of transportation said, warning motorists not to travel in 17 southeastern counties worst-hit by Florence.

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More than 54,000 homes and businesses were without power in the Carolinas on Friday afternoon.

One week after Florence made landfall as a Category 1 hurricane, North Carolina was still feeling its effects, Cooper said. “Some locations won’t see rivers crest until this weekend and flooding won’t subside until next week,” he said in another twitter post.

As floodwaters continued to rise, concerns grew about environmental and health dangers.

Duke Energy Corp DUK.N said on Friday that breaches in a cooling lake dam forced it to shut down its natural gas-fired L.V. Sutton plant in North Carolina. The utility said it could not rule out the possibility that coal ash from a dump adjacent to the plant, which formerly burned coal, might be flowing into the nearby Cape Fear River.

Coal ash can contaminate water and harm fish and wildlife.

The flooding from Florence has also caused 21 hog “lagoons,” which store manure from pig farms, to overflow in North Carolina, possibly contaminating standing water, according to the state’s Department of Environmental Quality. North Carolina is one of the leading hog-producing states in the country.

Several sewer systems in the region also have released untreated or partly treated sewage and storm water into waterways over the last week, local media reported.