The American Geophysical Union has conducted the first-ever "global inventory of lake colour". Past studies have looked at the health of up to 200 bodies of freshwater at a time, this research looked from space at the hues of 85,360 lakes and reservoirs worldwide over 7 years, using 5.14 million satellite pictures. Dr Catherine O'Reilly is a Professor of Geology at Illinois State University and one of the two lead authors of the study.