The Washington state Department of Transportation recently sought bids to replace a more than 60-year-old ferry that serves travelers needing to cross Lake Roosevelt between Lincoln and Ferry counties.

The Martha S., also known as the Keller Ferry, operates where State Route 21 meets the water near the confluence of the Sanpoil River, about 80 miles northwest of Spokane. It will cost about $12 million to replace, and the replacement project is being funded with a combination of federal and state funds, as well as $2 million from the Colville Confederated Tribes, says Al Gilson, a Spokane-based spokesman with the DOT.

Bids to replace the vessel were opened on Sept. 20. Those results weren't available before press time.

In addition to the planned replacement of the ferry vessel, the DOT plans to replace the north shore terminal, at a cost of about $1.6 million. Design and engineering work for the new terminal is to begin soon, Gilson says. The south terminal also will need to undergo some upgrades to adapt it to the new vessel's hull, he says.

The Keller Ferry is one of the only non-Puget Sound ferries in Washington, as well as one of the state's oldest, having been in continuous operation since 1948, the DOT's website shows.

The 80-foot long vessel has a maximum capacity of 12 cars, and it serves about 150 vehicles per day, Gilson says. Daily users include trucks, school buses, and passenger vehicles. Because of its rural location, the ferry has almost no walk-on users.

The new aluminum-hulled vessel will have a capacity of 20 vehicles and is expected to be ready for service by the spring of 2013. The current ferry needs to be replaced because parts to repair it are no longer manufactured commercially and must be custom made. The vessel's already limited capacity also is further reduced when large trucks are on board, the DOT says.

The length of the Martha S.'s crossing is 1 1/4 miles, which takes about 10 minutes at a top travel speed of 12 mph. There is no cost to use the ferry, which operates seven days a week between 6 a.m. and midnight, and its crew consists of eight people.

Wilbur is the nearest town to the south of the ferry's southern terminal at 14 miles away, and Republic, the closest town to the northern terminal, is 54 miles away.

Without the ferry, travelers on highway 21 would have to detour about 60 additional miles using mountainous county and tribal roads to get from one shore of the river to the other, Gilson says. That main detour would be to the west to Grand Coulee Dam and then northeast back to highway 21.

The ferry's north shore terminal needs to be replaced because the current terminal there has required frequent, extensive repairs.

Most recently, the ramp's flotation mechanism failed when it was being moved to a low-water level location, and that event interrupted ferry service for several days, the DOT says.