When one is not sure where a birding location is located, there are two good resources.
Click on "Birding Locations" then "Search for a locations"
Luna Res is there.
Or maybe even easier, on eBird go to "Explore Hotspots"
Fill in the bubble with the first few letters, eg, "Luna Re" and you get
a map and a list of all birds seen there in the past, recent trips there, etc.
LUNA Reservoir is not an official name, but a Cool nickname, so if you search on Google, you won't
find the Luna Res in Weld County, but rather you are directed to a nice reservoir in Spain, farther east.
Joe Roller, Denver