If you dream of cold river, it means at least two things. First, your dream of cold river means the water is un-inviting to touch. When this is related to waking life, it means you are faced with a challenge that makes the situation cold and hard to deal with. Dream imagery of a river can mean you have a source of water, or resource to utilize. You are going to survive with the help of this resource, but simultaneously, you have to deal with the tough environment. The dream interpretation of river is that the flowing water poses a challenge. You have to watch out to deal with existing conditions in your waking life.
What are your memories of a river? Your dream draws upon your existing memories of a river. This dream symbol was played in your dream to invoke specific meanings that your waking self knows. Your dream image talks to you in specific ways that only you know about.