Megan Bloom scored 22 points with four 3-pointers as the Chieftains improved to 5-1 with the non-league win Saturday at Mountain View.
Mountain View closed the gap to two points in the fourth quarter, but Bloom and Kate Kraft made 3-pointers, and Teaghan Cowles followed with a basket and Columbia River was back up by 10.
Emilly Moore led the Thunder (3-3) in scoring with 17 points, Christina Lundy had 15 and Hailey Hartney 12. The Thunder made 16 of 17 free throws.
Marion Lilly added 12 points for River, and Holli Jo Chose led the Chieftains with eight rebounds.