Because the rays were barely visible I stacked 6 godrays over each other as a quick fix. The material was already on additive and unlit.
I adjusted parameters on the material instance; power and opacity. Then I scaled and adjusted the ray in the right place.
Spawnrate: 70 & 35
Max Lifetime: 6.0
Blend Mode: Translucent
Spawnrate: 15 &15
Max Lifetime: 5.0
Blend Mode: Additive
Here the shaders are still compiling so you can see what is affected.
Originally it's on translucent, fitting for water.
I put it on additive and I can't see much difference, so I let it stay on this.
I did the same for this mist particle effect.
I deleted the particles systems you didn't really see clearly, which wasn't much, so the quad overdraw looks bad still. But every particle now has an additive material instead of translucent, so it should still have an impact on performance.
I thought maybe additive would work for the water as well, but it looked quite bland so I let it stay on Translucent.
Default: Default Lit + Translucent
Default Lit + Additive
Unlit + Translucent