The City of St. Helens Wastewater Treatment Plant is located at 451 Plymouth Street. It consists of two lagoons, an operations building, a chlorine building and a shop. It treats all of the domestic waste from both St. Helens and Columbia City. It also treats waste from a number of local industries. There are four employees at the plant, a Superintendent, two Operators, and a Pretreatment Program Coordinator. The hours of operation are Monday through Friday, 6:30 a.m. to 4:30 p.m. Along with the Treatment Plant, the operators also maintain nine sewer lift stations and one stormwater lift station throughout town.
The treatment process consists of two lagoons. When waste enters the plant, it is screened and enters the smaller 3 acre lagoon for primary treatment. After that, it is disinfected and flows into the larger 40 acre lagoon. Here, it mixes with the waste from the Boise Paper Mill. After the secondary treatment, it is discharged into the Columbia River. The typical flows to the river are between 6 and 10 million gallons per day.