Explanation:

 The provisions related to Inter-state water disputes have been included in Article 262 of the constitution which says:
(1) Parliament may by law provide for the adjudication of any dispute or complaint with respect to the use,distribution or control of the waters of, or in, any inter-State river or river valley.
(2) Notwithstanding anything in this Constitution, Parliament may by law provide that neither the Supreme Court nor any other court shall exercise jurisdiction in respect of any such dispute or complaint as is referred to in clause (1).

By using the powers of Article 262, Parliament enacted the ISWD Act. Now, the riparian issues are sent to a Tribunal under the ISWD Act, which are temporary and ad hoc interstate water dispute tribunals.
However, some states are able to obviate the above provision by using special leave petition in article 136. As per article 136, the Supreme Court may, in its discretion, may grant special leave to appeal from any judgment, decree, determination, sentence or order in any cause or matter passed or made by any court or tribunal in the territory of India.This is how some states are able to go to the Supreme Court when there is a clear and explicit bar on the jurisdiction of the courts in the case of a river-water dispute.