Excessive drinking, anxiety and depression are on the upswing in the Northwestern United States, apparently because of the Mount. St. Helens volcanic eruptions, social workers there believe. Even the social workers are affected, and service agencies in the state of Washington report an increase in absenteeism and stress among their employees. A major problem, according to social workers in the seven-county area around Mount St. Helens, is that people living near the mountain don't know whether the worst is past or yet to come, and this makes them feel helpless and frustrated. "Since this is the first time that there has been a major volcanic event in the United States in this century, it still is impossible to comprehend what it means to live with ash, with its constant movement and continued presence as a factor of daily living," the staff of the Washington State Department of Social and Health Services reported to federal authorities. "We do know, however, that there is a high potential for emotional reactions of frustation, depression and continuing irritability. These emotions, long continued, create stresses known to be ingredients of emotional and mental instability," said Dr. Calvin Frederick of the federal mental health office's disaster assistance program. Since the volcano's first eruptions in May, counselors and ministers in the Mount St. Helens area have seen an increase in depression, family conflicts and overuse of drugs and alcohol among adolescents and young adults, a federal official said. "People have to recognize their feelings about the volcano and realize that they aren't abnormal," Frederick said. "Many people moved away from Three Mile Island, but most have come back now," he said. "You have to learn to cope, to know what to expect and to separate myth from reality."