Outfall No. 051 at Los Alamos National Laboratory (LANL) is a discharge pipe connected to the Radioactive Liquid Waste Treatment Facility (RLWTF).
After November 2010, the RLWTF became a zero-liquid-discharge system. Since then LANL has been using a Mechanical Evaporator System (MES) to evaporate treated water into the air, and nothing has been discharged through the Outfall. Nevertheless, the Environmental Protection Agency (EPA) still includes Outfall 051 in the Clean Water Act permit that it issues to LANL.
This has a serious impact. The Radioactive Liquid Waste Treatment Facility manages a lot of hazardous waste, and it would normally be regulated by the State of New Mexico under the New Mexico Hazardous Waste Act. But, under an EPA rule called the Wastewater Treatment Unit exemption, if LANL is regulated under a Clean Water Act permit, Outfall 051 and its source, the RLWTF, are exempt from the New Mexico Hazardous Waste Act.