In the fall of 2005, dead and dying great blue herons (Ardea herodias) exhibiting emaciation, lethargy, inability to fly and a hard abdomen (steatitis confirmed at necropsy) were observed at Poplar Island and nearby Coaches Island (Rattner et al. 2006). Birds were hand captured at or near impoundments (cells) and ponds that contained large algal blooms, and because of poor prognosis were euthanized. Seemingly healthy great blue herons were subsequently collected at Blackwater National Wildlife Refuge. Blood and fecal samples were collected, and submitted to Antech Diagnostics (Lake Success, New York) for Avian/Exotic Combined Blood Count, Comprehensive Avian Chemistries, Fecal Cultures and Vitamin E analysis. Liver samples were analyzed for microcystin content (An and Carmichael 1994, Carmichael and An 1999; Cyano HAB Lab Wright State University, Dayton, Ohio). Below is a description of the organization of data that is presented on accompanying spreadsheets.