EPA Region 1 301(H) Monitoring Program

The Federal Clean Water Act requires that all municipal wastewater treatment plants use primary treatment (using gravity to separate solids from liquids) and secondary treatment (using special strains of aerobic bacteria [bacteria that need oxygen to grow] to break down the organic waste left after primary treatment) before discharging their water. In 1972, Congress passed the Federal Water Pollution Control Act Amendments, which required Publicly Owned Treatment Works (POTWs) to achieve secondary treatment capability by 1977.

After passage, some municipalities with POTWs that discharged into marine waters argued that this requirement might be unnecessary on the grounds that marine POTWs usually discharge into deeper waters with large tides and substantial currents, which allow for greater dilution and dispersion than their freshwater counterparts. As a result, Congress added section 301(h) to the Clean Water Act in 1977, allowing for a case-by-case review of treatment requirements for marine dischargers that applied by September 13, 1979.