"multiple uses" of a lake? Already that raises questions. If you read the short description on the official website, which I could paste here but let me get through it instead, it looks more like a placeholder as well as a "let's throw this on a list so that tourists go there - not that the place requires to be promoted any more.

Their first point about natural beauty could easily be granted. The setting is beautiful from every spot on around the lake. I stopped at lookouts as I was driving to Chichicastenango and the sunset was breathtaking. Now as for the archaeological sites they mention are probably also there but I sure didn't see any. Indigenous communities these days are more or less tourist towns. There is still a very "infamous" (as per local Guatemalans) hippie town - one of which I had the pleasure to meet up in Tikal later on my trip, the rest of towns were more or less markets and bars which boatmen trying to attract you to the lake crossing.

Maybe this was a great place in the 80s before mass tourism took over but at this point I would consider it a tourist hotspot without any unique value worthy of the name UNESCO.