How to create a brown inland water mask?

[Maytenus]

I know using black color in my .BMP water mask generates a generic "ocean" (dark blue) color... But what about a brown inland water? Which color should I use in my .BMP (or tiff) water mask to generate a brown water color.?

Thanks

[Max Perry]

There is a 'water class' mask similar to a landclass mask which is what provides the color of the default water.