"Wally the Lifeguard" - Ward and June were going to drive up to the lake and check on Wally (making me think it wasn't very close by).

Wasn't there another episode where Beaver and Larry went up there alone?

They went up there all alone in Borrowed Boat. Did they take a bus?

Also in Beaver and Violet Fred had to get his windjammer on the road to Friends Lake so it had to be miles and miles away like Shadow Lake in Happy Weekend.