How to avoid blurry white artifacts on reflective translucent plane?

Hello, after creating a pond in the level I’m building, I noticed some white blurry artifacts on the surface of the water when viewed at a certain angle. I’ve made some research and tried various setting on the water material, the lightning and so on, without success.

I think it’s a problem with translucency and/or reflections and it would be great if someone could explain me why the artifacts occur and how to get rid of them.

Thank you!

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