Creating a murky water fog effect

So I’m currently trying to create basically ‘murky water’. I can already adjust and make it so the water is murky looking from the outside, but I need to basically continue with that effect when swimming in the water. While post processing I can make the screen ‘darker’, that doesn’t stop being able to see all the way across the lake to the other side. I cannot seem to figure out which setting could allow me to do this. What I want essentially is a fog effect just within the water area. Right now I have a box with a water plane and post processing attached to it to create my water volume. My problem though is that I can’t restrict any fog effects to that square volume.

This is the effect that I want:

But I only want that effect to last when under the water of THIS specific lake. Other places I want to have clear water. Currently that fog effect spreads to the whole map. I can’t find any info on limiting exponentialheightfog or atmospheric fog to a specific area. I tried making it volumetric fog but that didn’t limit it to the boxed area I have it under. I’m assuming there’s no way to limit fog into one defined area because I can’t find any reference material to do it. So how else could I go about achieving this same effect? Any info or points in the right direction would be greatly appreciated.

ere’s a picture of what I mean by having it attached to the box for reference:

you need an post process material for the fog. you can mask it based on height and other stuff too

i have the nodes that ryan b made in this link that will mask the effect above the water plane, if you use the material in a bound post volume you can limit its size to just the lake.
the post should be enough for you to recreate them, but let me know if you want me to upload it for you.
you will also need to recreate the exponential height fog inside the material

Thank you! I appreciate the point in the right direction.

you can use volumetric fog with a box and applie on it a volume material i saw it in the live stream : Artistic Lighting & Spring #ue4jam Kickoff | Live Training | Unreal Engine Livestream - YouTube it around 10 min

hope it help you