N.M. Stat. § 62-9-2.1
Within six months after the effective date of these 1987 amendments to the Public Utility Act [Chapter 62, Articles 1 to 6 and 8 to 13 NMSA 1978], each sewer utility brought within the jurisdiction of the commission by virtue of these 1987 amendments to the Public Utility Act shall file with the commission an application, in such form as may be prescribed by the commission, for a certificate of public convenience and necessity covering its present plant, lines and system. Upon proof of the existence and operation thereof upon the effective date of these 1987 amendments to the Public Utility Act, the commission shall grant to the utility such certificate. The commission shall enter upon a hearing to determine whether the rate or rates of such a sewer utility in effect on the effective date of these amendments to the Public Utility Act are just and reasonable pursuant to Subsection D of Section 62-8-7 NMSA 1978 upon the filing with the commission of protests signed by ten percent or more of the ratepayers receiving sewer service from such a sewer utility. For purposes of this section, each person who receives a separate bill equals one ratepayer and each person who receives multiple bills equals one ratepayer. The protest shall be signed by the person in whose name service is carried. The protests shall be filed no later than sixty days after the filing with the commission of an application by the sewer utility for a certificate of public convenience and necessity as prescribed by this section. Each sewer utility filing an application for a certificate of public convenience and necessity under this section shall be required at the time of filing to give written notice to its ratepayers of the filing of its application and the ratepayers' rights to protest its rates under this section.
NMS § 62-9-2.1