From May of 2015 through September of 2018, water-quality data were collected at 178 locations from select tributaries, embayments, and nearshore lake locations along New York's Lake Ontario waterfront in support of the Great Lakes Restoration Initiative and the Lakewide Action Management Plan. These data include environmental, replicate, and blank samples of nutrients and suspended solids as well as field measurements of physical parameters (temperature, specific conductance, dissolved oxygen, pH, turbidity, phycocyanin relative fluorescence, and chlorophyll relative fluorescence).