This is the page that collectively describes all three lakes in the game. The lakes are not really places, but merely points on the map where one can get food by fishing just like harvesting events.
There is no layout as there is no map. Like harvesting events you just go to a lake and click on it to get a menu that asks you how long you want to fish.
There are three lakes: Buchanan Lake, Proctor Lake and O. H. Ivie Lake. Buchanan is the closest to the Shelter and is about 20 miles to the southeast. Proctor Lake is the farthest away and can be found roughly 50 miles to the northwest. O. H. Ivie lake lies 30 miles northwest of the Shelter.
These places are to fish, to get fresh food. A fish is worth 4 food. It is unknown if there are any differences between these places. The difference with random harvesting events is that the lakes stay on the map and can be used again and again.