If motorists had to limit their trips on interstate highways to four hours a day, the public would be up in arms. Shipping goods would slow to a crawl. First responders would be unable to reach most emergencies. And families would forgo trips and stay at home. Congress would be forced to act.

Yet Congress has been routinely allowing the nation's marine highway to silt in to the point where barges in some areas can be used only just before and just after high tide.

The Intracoastal Waterway is in danger of being impassable without dredging. And obtaining federal money for dredging is a yearly obstacle. It shouldn't be that way.

One problem is the formula used to allocate money. The more commercial traffic, the more money is available.

Problem: When parts of the Waterway are silted in, as at Breach Inlet between Sullivan's Island and the Isle of Palms, the Ashepoo and Coosaw rivers connector in Colleton County, and Town Creek in McClellanville, the commercial traffic decreases because barges and other vessels can work only when the tide is in.

Further, the formula doesn't count fuel shipments, fishing boats, dredge barges or recreational boats as part of the traffic.

Why not?

Those vessels contribute to the economic vitality of an area just as Nucor barges full of steel do. And just as motorists using I-95 to go on a shopping trip do.

Just as interstate highways must be maintained for the safety of their users, so should the Intracoastal Waterway - often called "the ditch."

Boaters could well be unaware that parts of the waterway are only three feet deep at high tide and parts nearly run dry. The channel is supposed to be 12 feet at low tide. Should boaters run aground, they could incur serious injuries to their vessels and themselves.

The Intracoastal Waterway was a project of the U.S. government to allow marine traffic safe routes in lieu of more dangerous routes in the open sea.

Channels between existing bodies of water were dug, eventually allowing marine traffic to go inland from Miami to Portland, Maine.

The portion of the waterway in South Carolina is 236 miles, from Little River to Port Royal.

The waterway is a federal interstate transportation corridor that predates the interstate highway system by nearly a generation. Some of the man-made portions date to the 18th century.

The maintenance of the Intracoastal Waterway should not be a year-by-year decision by Congress. The funding should be secure, and the funding formula should be updated to include fishing boats, dredge barges and recreational vessels.

In South Carolina and beyond, the waterway is more than a scenic asset.

It is a vital piece of the commercial shipping puzzle and deserves consistent, ample federal funding.