The Clean Water Act of 1972 prohibits discharging pollutants into wetlands without a permit.
The city also said that the plant is discharging pollutants like oil and grease in violation of permits.
No person may discharge pollutants, including mercury, into waters unless the person has a permit.
They say that even mills with supposedly closed systems often discharge pollutants into the surrounding water.
The town was forced to pay a $250,000 penalty for discharging pollutants into the Concord River.
This can mean that factories prevented by one inspector from discharging pollutants into the air are allowed to divert them to, say, water.
Fines for discharging pollutants into water supplies are to be increased.
The company was indicted by a Federal grand jury here in January on 78 counts of illegally discharging pollutants.
Commercial and industrial facilities that discharge toxic pollutants to the treatment plants may be very detrimental to treatment plant processes and the environment.
But some expressed concern that the regulation is too strict for plants discharging only pollutants similar to sewage from households.