It is named for Nathaniel Lyon, an early settler of the area who moved from Vermont in 1803 and died circa 1850.

The southwest end of Lyon drains into Cold Brook, thence into the North Branch of the Saranac River.

The west slopes of Lyon drain into Standish Brook, thence into Middle Kiln Brook, Upper and Lower Chateaugay Lakes, the source of the Chateaugay River, which drains into the Saint Lawrence River in Canada.

The northwest slopes of Lyon drain into Separator Brook, thence into Upper Chateaugay Lake.

In 1917, the New York State Conservation Commission erected a 35-foot-tall (11 m) Aermotor LS40 steel fire lookout tower on the mountain.