Best temp for water?

I work for a health club and we keep our lap pool temperature between 78-80 degrees. Recently, my boss requested some sort of article or authoritative piece justifying the temperature. I know I have seen articles in the past on 78-80 degrees being the best temperatures for lap swimming, but it was several years ago. Does anyone know of an article they have read commenting on this? Any help or direction would be fantastic. Thanks!