Fresh water is not a problem. Remove the focusing screen, lens, back n prism, dry whatever you can with a paper towel. If your oven has a pilot light in it (aprox 100°F)... Extend the bellows all the way out and put the camera (body, backs opened and prism (battery removed)) in there for a day or overnight till it dries out. Since the camera is mechanical there is nothing to harm aside from silt or dirt in the water it was immersed in. If all works, you're good to go. If not, it will need a CLA.
The focusing screen is easy enough to take appart if it is one with a couple layers. Wash everything with filtered water and pat dry, don't wipe if it has a fresnel lens or you will imbed dirt in the lens.
The prism may have a meter and may suffer damage from the fall not the water. Dry it out with the camera in the oven but remove the battery. Once it is dry try it out. If it;'s not working, well buy that hand held meter you've been eyeing for years.
Now the lens... the filter can be removed by taking out the glass, then cutting the ring to twist it out of the front of the lens. Does the lens rim have damage as well? Can you see any water in the lens? Does it still fire?