President Carter flew here today to inspect the damage caused by the eruption of Mount St. Helens after first declaring the state of Washington a major disaster area.

The president arrived in Portland, about 50 miles southwest of the still-steaming volcano, early tonight and went immediately to a meeting with state and local officials from Washington, Oregon and Idaho.

Carter is scheduled to view the volcano and the surrounding devastated areas from a helicopter Thursday, although fog and low-lying clouds may hamper his inspection tour.

There also was a possiblity that he will stop in eastern Washington state Thursday to view agricultural areas that have been blanketed by a layer of ash from the volcano.

Carter met with the state and local officials in nearby Vancouver, Wash., where he was briefed on the eruption and its aftermath by federal officials who have been operating relief efforts here. At the conclusion of the meeting, he praised the people of the Pacific Northwest for not panicking in the face of "one of the most devastating natural explosions our country has ever seen."

During the meeting, the president was pressed by Washington Gov. Dixy Lee Ray for a commitment of federal aid for cleanup and aid to victims.

"What do you need specifically?" Carter asked.

"M-O-N-E-Y," Ray replied.

The president made no additional commitments beyond his disaster declaration, but he was given estimates of some of the damage facing this region. Federal officials said the eruption may result in the loss of 70 million salmon, that it leveled 1 billion feet of timber with a value of $500 million and that the cost of cleaning up just the roads that have been closed by fallout of ash could be as much as $300 millon.

En route here, White House press secretary Jody Powell said the president had ordered the Army Corps of Engineers to begin immediately to dredge the Portland harbor, closed by silt and ash as a result of the violent eruption of the mountain early Sunday.

Powell said the dredging should be completed in several days and should allow at least one-way traffic in and out of the harbor, where about two dozen ships have been unable to leave.

The president, who has seldom visited the sites of natural disasters, decided abruptly this morning to fly across the country and inspect the devastated volcano area, White House officials said. They said there was no connection between the hastily arranged trip and Carter's desire to visit the West Coast before the important California presidential primary on June 3.

Carter campaign officials have had mixed feelings about a presidential visit to California, because of the cost involved. The president's trip to Oregon and Washington, certain to be a major news event throughout the West Coast, was paid for by the government.

Carter was accompanied on the trip by Interior Secretary Cecil D. Andrus, Agriculture Secretary Bob Bergland, Army Secretary Clifford Alexander, presidential science adviser Frank Press, and John Macy, administrator of the Federal Emergency Management Administration.

The entourage also included Sens. Mark Hatfield (D-Ore.) and Warren G. Magnuson (D-Wash.), and Reps. Les Aucoin (D-Ore.), Don Bonker and Mike McCormack, both Democrats of Washington.

Adviser Press told reporters that the United States has asked Japan for advice on cleaning up after the volcano because of Japanese experience with volcano eruptions.

White House officials also announced the formation of a scientific team, headed by Dr. Robert Wesson, an assistant director of the U.S. Geological Survey, to direct and coordinate the collection of scientific information about the eruption and its effects on the people and environment of this area.

News services reported the following:

The confirmed death toll from Sunday's eruption stood at 14, and 90 people were reported missing. The death toll was expected to climb much higher, with officials holding out little hope for those still unaccounted for.

Bad weather hampered search efforts today and obscured a lake formed on the Toutle River by rubble from the eruption. Geologists earlier had feared that the dam of debris would collapse and that two square miles of water 200 feet deep would crash down on two small Washington cities with a total population of 50,000.

Bob Christiansen of the U.S. Geological Survey said the dam appears to be settling and may become a permanent fixture. He said a similar dam was responsible for forming Spirit Lake during an eruption 300 years ago.