During 2010 to 2013, waterbird mortality surveillance programs used a shared protocol for shoreline walking surveys performed June to November at three areas in northern Lake Michigan. Timing (to day) and location (to transect) of carcass deposition and species affected were summarized. Using these observations, the broader goal of our study was to quantify the spatial synchrony of avian mortality events and explore whether within-year lake conditions (lake surface temperatures and the presence of algal masses) were related to the magnitude and periodicity of these mortality events. We generated the data on bird mortality, but we used publically-available data from the National Aeronautics and Space Administration for lake surface temperatures and algal masses as approximated by chlorophyll-a concentration (http://neo.sci.gsfc.nasa.gov/). As part of a Great Lakes Restoration Initiative study, the carcass data have also been used to assess between year trends (Chipault et al. 2015), some birds collected during surveillance were tested for botulism type E to assess the toxin presence across species (Chipault et al. 2015), some birds were also used in a gut content study to analyze what was consumed before death (Essian et al. 2016), and some of the spatially-explicit carcass data were used in backtracing models to estimate the source of the toxin in the environment (Kenow et al. 2016).