The Pink worm became popular in British Columia about 10 years ago. The fast moving spring runnoff eroded banks and deposited worms in the river. A worm floats downstream with no internal action,it follows the current seams and rides close to the bottom.
Duplicating this action, BC fishermen used a float and allowed a dead drift down seams.
In low visability they chose worms up to 6"long;for high visability they chose 3 or 4 inche worms.
Plastic worms make a very durable lure for fishing turbulent ,rocky streams particularly pocket water . However they have bee very successful in many kinds of water.