According to Niche.com, the best public high school in North Central Washington is Cashmere High. Niche accounts for academic performance, teacher quality, culture and diversity and reviews from students and parents, among other factors, to calculate its list. The website says that Cashmere is the 56th best public high school in the state. Other North Central Washington high schools on the list: Ellensburg is 97th, Wenatchee 111th, Chelan 120th, and Omak 138th.
The top public high school list can be found here.