If you are asking whether the law specifically states that you must tell your employer about any controlled substances, no, it does not. Not unless you need an accommodation.
If you are asking whether your employer can take any adverse action against you because you did not tell them, that can be a different story, depending on all the facts.
Two things I am tired of typing: 1.) A wrongful termination does not mean that you were fired for something you didn't do; it means that you were fired for a reason prohibited by law. 2.) The above answer, whatever it is, assumes that no legally binding contract or CBA expressly says otherwise. If it does, the terms of the contract apply.