How to Trace for water with out collision

Trace for water with out collision, How do I line trace for water if it has no collision, I need to know when my actor is walking through water, the level has a very shallow river made using a spline with a water material I’ve added a water physics material, line trace won’t return any info about the water cause it has no collisions, it only hits the landscape below the water that does have collisions.
Please advise to an easy fix for this, adding a physics volume below the water will be very difficult as the river is long, whinedy and undulating.

You can use custom per poly collision with block visibility (for trace channel)

Thanks, I added Box Simplified Collision to the mesh used by the spline, set it for Query only and visibility, here’s hoping it does not added to much strain to processing. I was trying to do this with out adding collisions to the river but looks like that’s not happening.