How make blueprint actor(fog/direct light) limited in some volume area

Development Rendering
1

I trying make swimmable water volume. Caustics light look bad on spot light, but nicer directional light works on entire level (not just in lake). It’s some way to set fog/postprocess in blueprint as local(like in UDK)? Thanks for idea

129062-blueprintvolume.png

129063-example.png