The National Oceanic and Atmosphere Administration is changing the navigational line that's guided boaters up the Atlantic Intracoastal Waterway for more than 100 years.
Affectionately called the "magenta line," the guide served as the recommended route up the East Coast's marine highway, which passes by Hilton Head Island, through Port Royal Sound and up the Beaufort River.
But now the exact magenta line is fraught with obstacles, like sandbars and shoals that have cropped up in the wake of lost federal funding for survey and maintenance of the waterway, said Beaufort Water Search & Rescue Squad Skipper Dick Jennings.
To reflect the changes, the NOAA Office of Coast Survey this month decided to change its charts to reflect the line as an "advisory directional guide" to keep boaters from getting lost in the braids of rivers and channels that surround the waterway. But it won't necessarily keep them from running aground.
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"The Intracoastal has definitely filled in with silt over the years," said Capt. Chris Morris, manager of Sea Tow Beaufort, Hilton Head and Savannah. "In our area, all the way down from Charleston, there's definitely a lot of hairy places. It is tough to navigate, and everything moves every year."
In areas like Skull Creek off Hilton Head, which is part of the waterway, silt and sand have shifted with the currents, making navigation trickier for some boaters, particularly the inexperienced, Skull Creek Marina general manager Jennifer Gentzel said.
Because of shifts in federal funding, it's been years since the U.S. Army Corps of Engineers dredged the waterway in Beaufort County, Jennings said. Without that maintenance, the magenta line's route now leads over new sandbars and shoals. For example, there's now a sandbar lurking just below the surface of the Beaufort River at low tide north of the Woods Memorial Bridge, he said.
If the government maintained its paved interstates the way it maintains its marine highways, commerce simply could not move, said Brad Pickel, Atlantic Intracoastal Waterway Association executive director.
Federal funding for waterway maintenance has been allocated to the biggest commercial-use areas in terms of tons per mile, so South Carolina and Georgia can't get that money. That's because big commercial interests like timber gave up using the waterway here over the years, and remaining companies can't move enough tons to qualify.
The ton-mile formula doesn't consider fuel shipments, fishing boats, dredge barges or recreational boats, even though Marine Corps Beaufort Air Station, for example, depends on the waterway for fuel shipments, Pickel said.
Now, NOAA partners with volunteers like the Beaufort Sail and Power Squadron to help monitor water depth and keep charts accurate, squadron commander Steve Mendoza said.
"We need to preserve and maintain our pristine water for the sea life and for folks to be able to enjoy the waterways, to enjoy boating and sailing," Mendoza said.
Although the waterway is disappearing, the magenta line won't quite.
After advocacy by the waterway association and others, Pickel said, the survey office will keep it on the charts, because people need to know where the waterway goes -- even when they can't go there.
Charleston Post and Courier staff writer Bo Petersen contributed to this report. Follow reporter Zach Murdock at twitter.com/IPBG_Zach.