(a) The attorney general shall enforce the provision of this title by injunction or other adequate remedy and as otherwise provided by law.
(b) If an action is instituted by the attorney general under this section alleging a violation of an NPDES permit or the failure to obtain an NPDES permit under Chapter 91 or Chapter 141 of the Natural Resources Code, the attorney general may not oppose intervention by a person who has standing to intervene, as provided by Rule 60, Texas Rules of Civil Procedure.