Washington State Copes With Flood Damage : Disaster: As rain slows, towns continue sandbagging campaigns to hold off the waters.

Rain slackened and river levels inched downward throughout a sodden western Washington state Thursday as residents and officials began to take stock of damage from widespread flooding after three days of drenching rains.

But most rivers continued to be under a flood warning, and downstream communities defended their ground with massive sandbagging campaigns. In the town of Mt. Vernon, population 30,000, hundreds of high school students and others laid down 175,000 sandbags to keep out the cresting Skagit River. It appeared to be working.

“We expect it will hold,” said Skagit County spokesman Ric Boge. “It looks like the effort is paying off.”

There was continuing concern farther downstream, where workers were furiously trying to shore up the levee protecting Fir Island, a low-lying farm community.

Gov. Mike Lowry has declared emergencies in 16 counties and put the National Guard on alert to assist in flood operations.

Government officials said it was impossible to tell how many people and animals had been forced from their houses, farms and trailer parks across Washington. Nearly 600 people sought out Red Cross shelters in nine counties Wednesday night, but many times that number were assumed to have fled the rising water. No deaths or injuries associated with the flooding have been reported.

Interior Secretary Bruce Babbitt toured stricken areas east of Seattle from a helicopter Thursday. He said he would report the situation to President Clinton and “see if we can provide just as much help as we possibly can under a great variety of federal responses.”

Officials predicted that these floods would rival the historic deluge that besieged the same areas in 1990. The flooding caused $150 million in damage that year.

A series of storms borne on warm, moist air originating in the central Pacific--the so-called Pineapple Express--began pelting the Puget Sound and western slopes of the Cascades last weekend, dropping as much as 15 inches of rain in the mountains and rinsing them of their snowpack.

By Thursday afternoon, 17 rivers--most of them in western Washington--were still under flood warnings, according to the National Weather Service.

The Skagit, Snoqualmie, Snohomish and Cowlitz rivers were expected to crest at or near their highest levels ever. At one point, water surged over Snoqualmie Falls at a rate 2 1/2 times flood level and 10 times its normal rate.