New York Consolidated Laws, Environmental Conservation Law - ENV § 21-0511. Further pollution

No person, firm or corporation, municipal or otherwise, shall create, establish, cause or maintain any source of pollution within the district, not existing on April 1, 1935;  provided, however, that after hearing and investigation on application of such person, firm or corporation, municipal or otherwise, the commission may issue such order relating to any such pollution as it shall find will best serve the public interest.