The Florida Department of Transportation announced Saturday that it is reopening the 14-mile stretch of Interstate 75 that was shut down due to rising river water under the highway. Officials said the Myakka River's water levels had receded enough to safely reopen the highway.

But, officials warned they may have to shut down the interstate again if water levels rise once more.

Officials had shut down I-75 from mile marker 179, near North Port and Toledo Blade Blvd. to mile marker 193, near Jacaranda Blvd, and long detours were in place.

I-75 is the main highway on the west coast of Florida and is a main route for travelers between Tampa-St. Petersburg and Fort Myers and Naples.

The Centers for Disease Control and Prevention put out a health advisory to healthcare professionals treating patients in areas affected by Hurricanes Fiona or Ian, telling them to maintain a high index of suspicion for carbon monoxide poisoning.

"Other people who may have been exposed to the same CO source may need to be identified and evaluated," the CDC said in a health advisory.

-ABC News' Eric Strauss

Four people have died in North Carolina since Friday in storm-related incidents, state officials said Saturday.

Two people died due to car accidents caused by storm conditions, one man drowned in his car and a fourth man died due to carbon monoxide poisoning from a generator.

Among those killed was a 25-year-old man who lost control of his vehicle and hydroplaned into another vehicle, a 24-year-old woman whose vehicle went off a wet road and struck a tree and a 22-year-old man who drowned when his truck left the roadway and submerged in a flooded swamp.

A 65-year-old man died Saturday from carbon monoxide poisoning from a generator running in his closed garage while the power was out. His wife was hospitalized.

“The storm has passed, but many hazards remain with downed trees, downed power lines and power outages,” said North Carolina Gov. Roy Cooper in a press release. “We mourn with the families of those who have died and urge everyone to be cautious while cleaning up to avoid more deaths or injuries.”

A flood watch remains in effect in parts of Virginia and West Virginia on Saturday as Ian’s remnants push north.

The storm is significantly weakened, but winds may still top 35 mph as rain covers the Mid-Atlantic and Northeast this weekend.

-ABC News’ Daniel Amarante

There is potentially major flooding in Orange and Seminole counties and St. Johns River, potentially up to Jacksonville in northeast Florida, Gov. Ron DeSantis said Thursday.

"The amount of water that's been rising and will likely continue to rise today, even as the storm is passing, is basically a 500-year flood event. And I know Seminole County has done evacuations, I know they've opened shelters, but we're gonna see a lot of images about the destruction that was done in southwest Florida and obviously we have massive assets there," DeSantis said.

"This storm is having broad impacts across the state and some of the flooding you're going to see in areas hundreds of miles from where this [storm] made landfall are going to set records. And that's going to obviously be the things that will need to be responded to," DeSantis added.

The damage caused by the storm will likely take years to repair, he said.

"You're looking at a storm that's changed the character of a significant part of our state. And this is going to require not just emergency response now, in the days or weeks ahead. I mean, this is going to require years of effort to be able to rebuild and to come back," DeSantis said.