New York Consolidated Laws, Public Service Law - PBS § 89-p. Powers of the department

The department shall, with respect to out of state water-works corporations which are affiliated with in-state water-works corporations and which provide water to such in-state corporations for eventual retail to New York consumers, keep apprised of, attend and monitor, and, where possible, formally intervene in rate cases brought by such out of state corporations before the appropriate regulatory agency of such other state.  The commission shall consider and utilize information secured therefrom in determining whether rate increases sought by such affiliated in-state corporations are in the public interest.