Colusa is a city in Colusa County, California, located in the Sacramento Valley region of Northern California. The city has a population of approximately 5,971 people (as of the 2020 census). It is the county seat of Colusa County and serves as a hub for agricultural activity in the surrounding area.

The Colusa National Wildlife Refuge is located in Colusa, California and is managed by the U.S. Fish and Wildlife Service. It is a protected area that provides important habitat for migratory birds, as well as other wildlife species.