Response of Onondaga Lake to Restoration Efforts

The continuing restoration program for polluted, hypereutrophic Onondaga Lake, is examined, including descriptions of ecosystem responses to reclamation measures and evaluations of the various characteristics specific to the lake as they may affect future responses. Major responses to the program have included: (1)Substantial changes in phytoplankton composition; (2)reduction in concentrations of heavy metals; and (3)a dramatic increase in zooplankton biomass. Despite a major reduction in phosphorus loading, phytoplankton biomass has remained essentially unchanged. Further reductions in phosphorus loading, anticipated with the new (1981) tertiary sewage treatment plant, may result in phosphorus limited phytoplankton growth. The increase in zooplankton implies increased phytoplankton turnover rates and phosphorus recycling within the lake, which may prolong future phytoplankton blooms.