More and more states assess discharge permit fees to pay for the NPDES program. Generally, within a given state, the fees are the same for similar types of NPDES permits.
Some states, such as Indiana, assign fees associated with the volume of discharge. Another option is to link fees to the toxicity of the discharge. This is not currently done in any state. These approaches can provide incentive to strive toward the Clean Water Act goals of eliminating discharges and prohibiting toxic discharges.
Without fees, the NPDES program is supported by a state’s general fund (or the federal budget if EPA runs the program).