Ark. Code Ann. § 14-199-401

All cities of the first class whose population exceeds seven thousand (7,000) according to the official federal census now owning both a light plant and a water plant which are operated by separate boards or commissions, the light plants having been constructed pursuant to Arkansas Constitution, Amendment 13 [repealed], and the water plants having been constructed by an improvement district embracing the city as a whole, are authorized and empowered to adopt a municipal ordinance providing for the consolidation of the boards or commissions, and for the joint management of the water and light plants by the consolidated boards or commissions.