Nogales Wastewater Fairness Act This bill directs the U.S. Section of the International Boundary and Water Commission to charge Nogales, Arizona, no more than an equitable proportion of the costs for operating and maintaining the Nogales sanitation project. The sanitation project includes (1) the International Outfall Interceptor and the trunkline, which is a sewer line that carries wastewater along the U.S. and Mexico border; and (2) the Nogales International Wastewater Treatment Plant. The bill declares that Nogales is not obligated to contribute any capital costs of repairing or upgrading the project.