Lac-Nilgaut is a large unorganized territory in the Outaouais region, Quebec, Canada. With a surface area of 9,851 km2 (3,803 sq mi), it makes up over 70% of the northern portion of Pontiac Regional County Municipality. Lake Nilgaut drains via the Nilgaut creek into the Noire River, a major river that, together with the Coulonge River, bisects the territory.