Typically, produced water is non-hazardous. If it is determined that your produced water is a hazardous material (e.g., corrosive, toxic, flammable), then an SDS is an appropriate means of communicating the hazard to workers, haulers and the product receivers. It is certainly best practice to have a Safety Data Sheet for TDG purposes even if the product is not classified for TDG, to prove to inspectors this has been considered.