Grand Island is an unincorporated area in Colusa County, California, on the Sacramento River.

It lies at an elevation of 33 feet (10 m).

The name refers to the area between Sycamore Slough and the Sacramento River, including the town of Grimes and the steamboat stop at Eddy's Landing.

The region is heavily cultivated and in 1891 was described as full of "a thrifty class of people".

This Colusa County, California-related article is a stub.