The North Olmsted Wastewater Treatment Plant (NOWWTP) is located at 23775 Mastick Road next to the Cleveland Metropark's Rocky River Reservation.  The plant is classified as a Class III facility by the Ohio Environmental Protection Agency.

The city's original plant was constructed in the late 1950's as a single stage activated sludge treatment facility.  The original plant was constructed concurrent with intercepting sanitary sewers in the unsewered but heavily developed, poorly drained area in the the north eastern and central portions of the city.

A Report on Sewerage for the City of North Olmsted, Ohio in 1957 recommended that the City of North Olmsted construct a complete wastewater treatment works to serve the city.  The 1957 recommendations presented a long term, phased program for constructing a separate sanitary sewer system throughout the city, as well as a large, centralized wastewater treatment plant to serve a projected 37,000 population.

Beginning in the late 1960's, higher water quality standards and expansion of the North Olmsted sanitary sewer system required expansion and upgrading of the original Wastewater Treatment Plant.  Between 1968 and 1973, the city completed construction of its major sanitary intercepting sewers by extending sanitary sewer service to the west and southwest.  Advanced secondary wastewater upgrading became necessary to protect Rocky River water quality as the city's service area population increased.

The plant was greatly expanded in the early 1970's to provide activated sludge treatment for a design flow rate of 9.0 million gallons per day (mgd) because of additional growth in the sanitary sewer system service area.

Beginning in the early 1980's, the Wastewater Treatment Plant underwent additional improvements targeted toward providing for a tributary population of 60,000 through the year 2000.  These improvements were designed to allow the treatment facility to meet increased removals of ammonia nitrogen for the plant effluent and to reduce odors from the solids handling facilities.  This treatment was required by the Ohio EPA following enactment of more stringent allowable in-stream ammonia toxicity concentrations.  It was also intended to minimize odors in the thermal conditioning unit process.

The thermal conditioning unit process was removed in 2000.  In its place a centrifuge was installed.  It operates by rotating at a very high speed in order to separate the liquids from the solids.

The NOWWTP and the Collection System are currently undergoing a major upgrading.  The upgrade project is in its final design and construction is scheduled to begin, in the Collection System, late this autumn.  Construction of the Plant is scheduled for some time in 2011.