* Emergency messages being sent to residents in harm's way
* Potential flood zone encompasses some 3,500 homes
* Dead fish left on highway as waters recede (Adds details on deaths, flooding in North Carolina)
CHARLESTON, S.C./RALEIGH, N.C., Sept 24 (Reuters) - T housands of people in and around the city of Georgetown, South Carolina, were urged to evacuate on Monday as two rivers gorged with rain from long-departed Hurricane Florence will flood the area this week.
More than 10 days after the storm made landfall and killed 46 people mostly in North Carolina, several rivers throughout the state continued to rise. Georgetown is expecting floodwaters of 5 to 10 feet (1.5 to 3 m) as the Pee Dee and Waccamaw rivers overrun their banks in coming days.
Emergency management officials began sending recorded telephone messages to residents in harm's way and will go door-to-door in the next few days, Georgetown County spokeswoman Jackie Broach-Akers said.
The Georgetown County administrator, Sel Hemingway, told a news conference the area was expected to see peak water levels from Wednesday evening, with the deluge threatening to cut off highways and isolate communities.
"There will not be an official evacuation order," he said, but said people in the flood zone need to get out before the waters come.
The potential flood zone encompasses some 3,500 homes in Georgetown, 37 miles (60 km) south of Myrtle Beach, and the coastal resort community of Pawleys Island where as many as 8,000 people live, Broach-Akers said.
The county opened two emergency shelters on Monday, and hotels outside the flood zone in nearby Myrtle Beach were offering discounts for evacuees. Public schools will be closed until further notice, Broach-Akers said.
First responders from around the state were assisting in relief efforts. State transportation crews were working to erect temporary dams on either side of U.S. Highway 17, the main coastal route through the area, and National Guard engineers were installing a floating bridge at Georgetown in case the highway is washed out at the river.
STRANDED DEAD FISH
The National Weather Service said flooding from Florence would likely persist in coastal parts of the Carolinas for days as the high-water crest of numerous rivers keeps moving downstream toward the ocean.
In North Carolina, where 35 people died due to the storm, Governor Roy Cooper said on Monday that seven rivers in the southeast part of the state were at major flood stages and three others at moderate flood stages.
"Florence is gone but the storm's devastation is still with us," Cooper said in a statement.
The storm dumped 30 to 40 inches (75 to 100 cm) of rain on Wilmington, North Carolina, alone after making landfall nearby on Sept. 14. Heavy flooding left a commercial section of downtown Wilmington under at least a foot of water on Sunday.
Insured losses from Hurricane Florence will range from $2.8 billion to $5 billion, RMS, a risk modeling and analytics firm, said on Monday.
Flooding in Wilmington was expected to peak on Monday along the city's Water Street riverfront, where many businesses had stacked sandbags in advance, city spokesman Dylan Lee said.
Receding flood waters left hundreds of dead fish stranded on a highway near Wallace, about 35 miles from the nearest beach, according to the Penderlea Fire Department, which posted video of firefighters hosing the fish off Interstate 40.
About 5,000 people across North Carolina were rescued by boat or helicopter after the storm made landfall, twice as many as in Hurricane Matthew two years ago, according to state officials.
(Reporting by Harriet McLeod in Charleston, S.Carolina and Gene Cherry in Raleigh, N.Carolina; additional reporting by Rich McKay in Atlanta, Steve Gorman in Los Angeles, Gina Cherelus in New York, Suzannah Gonzales in Chicago and Jon Herskovitz in Austin, Texas; Editing by Leslie Adler and Lisa Shumaker)