Packsaddle Lake features 5 miles of hiking trails near Tetonia, ID.
From Rexburg, take State Hwy 20 north to State Hwy 33. 20+ miles out you'll see a sign for Elk Ranch. Turn right there. Follow the road for 5 miles. You'll get to a gate in an old ranch fence. There will be a sign for Packsaddle Lake there.
http://www.tripleblaze.com/trail.php?c=3&i=1450