SIOUX FALLS, S.D.(KELO)- Law enforcement agencies at all levels in South Dakota have taken down four major drug distribution rings.

54 defendents have been prosecuted…with sentences racking up more than six centuries of combined time in prison.

U-S Attorney Ron Parsons says it’s the result of weariness with the problem, and determination to stop it.

Parsons says the success is a result of tribal, state, local and federal law officers working closely together.