EPA is issuing this Order to place the City of Cottonwood (the ÂCity or ÂRespondentÂ) on an enforceable schedule to comply with the SDWAÂs Âmaximum contaminant level (ÂMCLÂ) for arsenic in the drinking water delivered by the City to its customers. MCL is defined under 40 C.F.R. § 141.2 as the maximum permissible level of a contaminant in water that is delivered to any user of a public water system.