Montana ski area operators must take reasonable care to keep skiers, snowboarders, and tramway passengers safe. They are required to: 

1. Equip all trail grooming vehicles with flashing or rotating lights while they are in use. 
2. Clearly mark hydrants and other snowmaking equipment on ski slopes with visible signs. 
3. Maintain trail boards in noticeable locations, showing a map of the ski area, boundaries, and the difficulty levels of the trails. 

Additionally, ski area operators must: 

1. Post a notice requiring skiers to use ski-retention devices. 
2. Indicate which ski slopes and trails are open or closed. 
3. Display the current skier responsibility code from the National Ski Areas Association in a visible location. 
4. Post skier and snowboarder responsibilities in a noticeable place. 
5. Mark designated freestyle terrain with a symbol recognized by the National Ski Areas Association. 

However, ski area operators do not have any duties to trespassers or unauthorized users. 

For aerial tramway passengers, operators must ensure that tramways and ropeways are properly built, operated, maintained, and repaired according to industry standards.