Intensive sampling of the offshore waters of Lake Ontario occurs on a five-year cycle. The 2003 and 2008 binational sampling program is known as the Lake Ontario Lower foodweb Assessment (LOLA). Research cruises were conducted in spring (April), summer (July or August) and fall (September) along several north-south transects. This data package includes epilimnetic (surface layer) and whole water column measurements for zooplankton size (mm), density (#/m3) and biomass (mg dry weight/m3) by species for each site. Veliger size and density from these tows are included as a separate file. Other trophic indicators measured during this program include nutrients (total phosphorus, dissolved silica), water clarity (secchi depth), dissolved oxygen, chlorophyll a, and an assessment of phytoplankton, the microbial food web and the benthic community.