Stain for a sea vall

I have a sea wall on an inland lake, that due to the current drought is 100% exposed. Normally there is 3' underwater and 2' above. Half the wall was replaced 20 years ago, and the other half is about 50 years old. So there are four color shades; old underwater, old above water, new underwater, new above water. I'd like to stain it a single color now that I have the opportunity to work on the whole thing. Is there a stain that will survive being totally immersed, and will it do damage to the water if it deteriorates?