May 1 (Bloomberg) -- Maine Governor John Baldacci declared an emergency in the state's northernmost county as rising floodwaters forced hundreds to evacuate, damaged buildings and threatened to overwhelm dams and bridges.

Only one bridge between the northern end of the state and Canada is open, in Madawaska, the Maine Emergency Management Agency said. The International Bridge over the St. John River between Fort Kent, Maine, and Clair, New Brunswick, closed as floodwaters rose above the span.

``There are people who are losing their property, their homes and their livelihoods,'' Baldacci said in a statement. ``I looked at the International Bridge that connects Maine and Canada and it's ready to wash away.''

Baldacci flew to Aroostook County, which includes Fort Kent, from the state capital of Augusta yesterday to survey the flood damage and has requested assistance from the Federal Emergency Management Agency.

About 600 people left homes in the county, where melting snow following a ``major rainstorm'' this week caused rivers and streams to leave their banks, agency spokeswoman Lynette Miller said.

``It's not quite growing season up here yet, which has a pretty huge effect on runoff,'' said Mark Turner, a hydrologist with the National Weather Service in Caribou. ``If the grasses are growing and the leaves are out, a lot of the water sits on the leaves. Since it's too early for that, it just ran off into the rivers.''

`Close-Knit Community'

No injuries or fatalities have been reported, although three people had to be rescued yesterday downstream from two dams that are in danger of breaching, Miller said. At least 140 homes surrounded by floodwaters may be damaged, she said.

The American Red Cross opened a shelter in the University of Maine's Sports Center in Fort Kent, yet only about 20 people stayed there overnight as most residents chose to bunk with friends and relatives.

``It's a very close-knit community; they take care of their own,'' Miller said in a telephone interview.

Almost 200 inches (508 centimeters) of snow fell in Caribou during the past winter, surpassing the previous record of 181 inches in 1954-55, Turner said.

The melting snow, combined with 4 inches of rain that fell on the region this week, caused already-swollen rivers to rise even higher, he said in a telephone interview.

`Very Lucky'

``We went into a relatively dry April and a lot of that melted out,'' Turner said. ``We actually saw the ice move and had concerns of river flooding from the plain snowmelt for the first half of the month of April. We're very lucky we didn't get a significant rain impact on top of that snow pack, or things could have been a lot worse.''

The St. John crested at more than 30 feet shortly after midnight local time, surpassing the previous record of 27.3 feet set on April 30, 1979, and the International Bridge can't be examined until the river is safe for divers, which ``may be several days,'' Miller said.

About 45 roads throughout the state were flooded or closed, including a stretch of U.S. Route 1 between Fort Kent and Madawaska, and four bridges have been shut until they can be inspected after waters recede, according to a statement from the Maine Emergency Management Agency.

Bridge Supports

Flooding damaged the supports of the Tucker Bridge, which carries traffic over the Pasadumkeag River, dropping the span 7 inches, the agency said.

Many flood watches and warnings issued by the weather service for northern Maine are set to expire today as water levels drop, and ``things are looking OK,'' John Bannen, community development director for the town of Fort Kent, said in a telephone interview.

``The situation with our rivers has kind of stabilized,'' Bannen said. ``The St. John River is dropping a little bit, which is good news. We're still working on the Fish River. So far, so good right now and the weather's cooperating. We've got everybody evacuated that needed to be evacuated, but until we get the clear, everybody's going to have to stay out of the downtown area.''

Flooded buildings at the University of Maine's Fort Kent campus forced the school to close for the rest of the week and evacuate about 150 resident students, according to a statement posted on the school's Web site.

Aroostook County is the center of Maine's potato industry. Its seat is Houlton, about 154 miles northeast of the state capital of Augusta.

The county, named for an American Indian word meaning ``beautiful river,'' is the state's largest by land area --bigger than Connecticut and Rhode Island combined -- and has about 74,000 residents.

To contact the reporter on this story: Chris Dolmetsch in New York at cdolmetsch@bloomberg.net.

Last Updated: May 1, 2008 14:51 EDT