If you are leaving the Yellowstone, NP via the north-east entrance, you will be on the Beartooth Scenic Hwy. This takes you through Cooke City, MT, and a few miles up the road is the turnoff to Chief Joseph Hwy.
This small lake is right off of Chief Joseph Hwy. One end of Chief Joseph Hwy begins at the Beartooth Scenic Hwy, and ends in Cody, WY. Chief Joseph Hwy is a very scenic road, especially during early Fall when Fall colors are at their best.