ANCHORAGE, Alaska (AP) - The Matanuska River is swollen and threatening riverfront properties. The Anchorage Daily News says the river is surging with snowmelt brought on by 70-degree temperatures this week. The Mat-Su Borough says the river this year is thundering along at 20,000 cubic feet per second. Borough spokeswoman Patty Sullivan says people who are using the river for recreational purposes should stay off it. Sullivan says the concern is flooding in Butte. In Sutton, the problem is erosion. One riverfront property owner lost 35 feet of land in two days. The river is expected to crest this weekend.