Is there a way to exclude a material/mesh/thing from a post-processing volume/effect?

I have a depth-fog type of post-process effect in my project. Works well, but has an odd interaction with transparent materials.

W/o PP, my water seems to be fine:

When I enable post-process fog (samples scene-depth and multiplies by a color based on distance), it affects everything, as expected, but when applied to the water, makes the transparency/opacity change so I can see underwater features at a distance…

Suggestions? Is it possible to have my cake (water) and eat it too (PP-effect)?