The changes are the result of a lawsuit brought against the City whereby they were required to perform a cost of service (COS) study to ensure that all dischargers to the system were paying their fair share of the treatment costs. The result of the COS study caused rates to go down for some dischargers, while up for most. The study also created three potential rates for industrial users, depending on how their process water is treated i.e. direct land application, primary plant treatment (which includes tertiary treatment) and the potential for a third rate class which received an intermediate level of treatment between the two. See rate details in the below chart.