The north side of Kibby Mountain drains into the East Branch of the Moose River, then into the South Branch of the Moose, the Moose River, and the Kennebec River.
In the region surrounding Kibby Mountain, the northern slope directs water into the East Branch of the Moose River, which subsequently flows into the South Branch of the Moose, before emptying into the larger Moose River and ultimately the Kennebec River.