The Oyster Bay Sewer District, located on the north shore of Long island, 25 air-miles east of New York City, was established on 17 August 1926 by action of the Town Board.

The original facilities served an area of approximately 975 acres with 20 miles of sewer mains and employed primary treatment processes. After solid wastes had settled to the bottom of an Imhoff Tank, the liquids were chlorinated and discharged into the harbor. The solids were dewatered, utilizing a sand filter collection system and then buried on the Treatment Plant grounds.

In the 1960's the three-man Board of Commissioners authorized the design and modernization of the facility to secondary treatment standards for a maximum flow of 1.2 MGD. Funded by a tax supported bond issue, the design abandoned all structures of the original plant except the receiving wet well. Sewage now passed through a bar screen and settling chamber to remove rags, sand and other debris. Also added to the plant were primary and secondary settling tanks, two trickling filters for secondary treatment, a sludge digester and an upgraded chlorination system.

The early-1990's saw a $6-million upgrade of the Treatment Plant to a design 1.8 MGD flow. Added to the system were a new wet well, automated bar and screening chamber, increased pumping capacity, additional primary and secondary settling tanks, four rotating biological disc systems, and enlarged chlorine contact chamber, replacement of the liquid chlorine system with safer sodium hypochlorite, and effluent discharge pumping system and an emergency diesel-powered generating system. Today the District services approximately 1,700 connections to its collection system at an average daily flow of 1.2 MGD.

The District is managed by three elected commissioners and staffed by nineteen employees providing 24 hour coverage, 7 days a week. Funded by a tax levy based on assessed valuation, the District's 1998 budget was 2.5-million dollars.