Ice Gives Way Under Twin Otter

April 20/14-The Transwest Air de Havilland DHC-6 200 (C-FGLF) operating on skis had landed at Scott Lake NT and was taxiing to the un-loading area. The aircraft began to break through the ice into slush. There was a jolt and the aircraft began an un-commanded swerve to the right. The crew elected to continue taxiing and once clear of the slush applied full power and took off. As the aircraft circled for a second attempt the crew noted a lack of resistance when moving the steering tiller. The crew determined that the nose gear had rotated out of position and elected to return to Stony Rapids (CYSF). An emergency was declared and the subsequent landing was uneventful. The aircraft was shut down on the runway with the nose ski rotated 180 degrees. Inspection revealed that the torque links and steering linkage were broken.