Within 180 days of the effective date of this ordinance, the water consumption of the 250 largest water users and the 250 largest sewer system users in the City of Los Angeles shall be audited. These audits shall be conducted by the owner or a representative of the owner in accordance with guidelines established by the Department of Water and Power. The results of these audits shall be reported to the Department of Water and Power by the owner or a representative of the owner.