Molalla, DEQ sign agreement on wastewater discharge permit
On April 1, the City of Molalla and Oregon Department of Environmental Quality signed a new agreement to amend the city's wastewater discharge permit. The permit sets the standard for the concentration of treated water discharged to the Molalla River.
Sewage from Molalla homes and businesses is treated at the Molalla Wastewater Treatment Plant along the Woodburn-Estacada highway.
In summer, the treated effluent is used for agricultural irrigation.
In winter, effluent is treated and returned to the Molalla River. High winter flows from rain and snow increase the river's capability to accept treated wastewater.
"We are grateful to DEQ for working with us on the best method to protect the environment and lower our residents' long-term sewer rates," City Manager Dan Huff said. "This is the latest development in our partnership with DEQ."
Huff admitted he was thrilled that the city and DEQ could reach an agreement on the issue.
For the past 40 years, Molalla's permit required the city to achieve a standard far more stringent than EPA and DEQ guidelines. While most other wastewater utilities have a biochemical oxygen demand (BOD) limit of 30 mg/L (milligrams per liter), Molalla's limit was 10 mg/L.
Earlier, Molalla took steps to improve operation of the existing wastewater treatment plant to produce the best quality water. Despite these costly upgrades to the city's wastewater plant and equipment, Molalla could not consistently meet the strict standard, leading to permit violations and fines.
DEQ and the City of Molalla collaborated over the past two years to determine what limit would best protect the river's ecosystem. Using a data-driven approach, DEQ approved a limit of 25 mg/L which Molalla is capable of meeting 95% of the time.
In October 2020, the city secured a low-interest loan from the Clean Water State Revolving Fund, which is administered by Oregon DEQ. This loan will help fund the design and eventual construction of an upgraded wastewater treatment plant. The new plant will ensure the city can meet the new discharge permit requirements.
To learn more, go to https://www.cityofmolalla.com/publicworks/page/wastewater-treatment-plant-improvements.
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