The old Water Filtration Plant, located adjacent to the old Pump House, was designed by architect David Morey, Jr. and constructed in 1923. In 1930 the facility closed when the lake ceased to be used as a water supply (except for a few years during the drought of the 1950s).

Currently, the building is vacant. Unfortunately, a recent proposal to convert the interior of structure for use as office space, meeting rooms, and a research center fell through.