A man driving a 20-foot ski boat on Newman Lake ran over his wife after she was thrown into the water Wednesday and the boat propeller severed her left arm, a Spokane County sheriff's deputy said.

The woman was taken to a nearby hospital and was expected to survive.

Robert Kienel, 27, of Spokane, was arrested for investigation of assault by watercraft, a Class C felony, Marine Deputy Patrick Bloomer said in a statement.

The deputy said the couple took possession of the ski boat Wednesday afternoon and the woman was riding on the boat's bow while the man drove. She was thrown into the lake when her husband took a hard turn at about 30 mph, the deputy said.

The arm, severed below the elbow, apparently sank and emergency crews could not recover it.

Bloomer said the floor of the boat was "littered with empty beer and wine" containers.

The boat was seized as evidence and the case remains under investigation.