If you come from Ketchum/Sun Valley go out Sun Valley Road which will turn into Trail Creak Road.  The road will turn to dirt and continue over the Trail Creek Summit, after 18 miles from Sun Valley turn left on North Fork Road which has a sign. After turning go up this road 1/2 mile and take the first  left and after descending down the driveway  you will see the cabins on the river, welcome to the Big Lost Ranch!