This trail is accessed by where the Brown Road passes under the power line. Turn left (east) and follow the jeep trail under the power line to where you can turn left on a two track road that drops down a sub canyon.
This is an old, washed-out dug way that you can ride as fast as you dare. This takes you to the bottom of Moody Canyon where an old dam was constructed to get water for the livestock used on the farms of the upper reaches of the Rexburg bench.
You'll want to contemplate the effort used to build the dam and construct the canal using only horse and hand labor. This is where the fun starts as you find your way downstream and follow the old canal on a fun, flowing singletrack with lots of beautiful views of the creek below you.