If you find yourself facing a water rescue always remember to cover your A.S.S.!
Assess the scene - make an overall assessment of the scene and keep your safety first! What is going on? What happened? Where is the victims? Who needs help first? How should we get to them and get back? Is there hazards downstream to be concerned about if I go after them? Can I accomplish this rescue? Do we have the right gear? This may seem like a lot of questions to answer but for some, it can take seconds.
Set up Downstream Safety and a Upstream Spotter - If there are only a few of you and you are not concerned about upstream traffic or debris floating down toward the incident area than at least set up downstream safety until more people arrive.
Send in Rescue (and possibly for help) - Keep the rescue as simple as possible based on your initial assessment and get to work!