I'm trying to research the use of small shelters near water sources to cool food products such as milk ?

they are called spring houses

Around here they used to use root cellars...I am not sure of what you are describing. Root cellars were like small rooms dug down in the dirt with a door. You would put shelving and baskets in there to keep the canned/preserved items cool in the summer and to keep potatoes, carrots, apples in the winter from freezing. As for milk...The milk would be brought in daily and most farms would not have that much extra...they would drink it, bake with it, and use it up as fast as they milked the cow. Goat milk would be used for problem babies or baby animals.

my grand father used spring water to keep the milk cool.

Are you talking about a root cellar?

http://www.motherearthnews.com/Modern-Homesteading...

http://waltonfeed.com/old/old/cellar4.html