Originally Posted by Diver Dan
There was one more possibility given where you caught it. There are also Golden Trout in the park. However, they don't seem to have spots below their lateral line so I am going to say Rainbow also. Here is a Golden Trout with nice par marks.
Looking through my golden pics from the summer I found a pic with a golden trout that has 2 spots below the par marks. Its not quite like the fish he posted, but it isn't impossible it seems.
You might never know for sure, but I would say with a decent confidence that it is a rainbow.