I saw submerged timber very frequently, Tex.
To keep the bugs out of the pine and the blue stain down and the rot to a minimum, my farmer type customers throw the logs in the farm pond until one of us portable millers can get to them. I have sawn pine that has been deliberately submerged for over a year and find it to be just as good as it was when it was put in the pond. The bark will slip after time but that's ok and the wood surface is slick as can be but that's ok too. Sometimes the log smells of pond silt but I haven't noticed it being inside of the log. (I have sawed cypress that has been submerged for a hundred years and it stinks through and through but it goes away with drying)
It has been suggested by others that cut submerged wood to saw it as soon as possible so that the log doesn't begin to check. When I saw submerged logs they have been out of the pond for maybe a day and usually are being dragged to me directly from the water.
I have sawed pine that has been submerged for a hundred years and the sap wood is no good but the hearts are good. If you are not talking about many years then my experience is that the log will be in great shape.