Stayed at Little Bitterroot Lake last year(Aug 2018) for 3 nights and had a great time. 

After seeing the crowds closer to Kalispell, we enjoyed the slower pace of Little Bitterroot lake. Got a great site, where the tent literally opened to a beautiful view of the lake. 

Nice clear lake for swimming or fishing for trout. All types of boating is allowed. 

We saw many eagles fishing for dinner, and even a snake swimming in the lake.