Hey there, thank you for getting in touch and for your support!
Although I'm not familiar with the mentioned water shader, you may achieve this by setting a higher Render Queue on what you wish to be drawn later, so in this situation the plane that is behind would have it's value higher so it's rendered after the one on top, effectively eliminating that blend.
In the example below, both surfaces use the same shader and have a different material, so they can hold different settings, and I've left the top one's Render Queue at its default value of 3000, setting the one below to 3001.

Please let me know if this helps, thanks!