Here are four replacement river textures of varying types and colour variations.
Just drop the stream.dds file into the \Combat Flight Simulator 3\assets\Texture
folder if their is no texture folder within the assets folder create one then drop
the stream.dds into the texture folder you created. To revert back to stock just
delete the stream.dds from the texture folder.
Thanks to: wolficatZ, Private_Ryan, jerry black, What A?, JG53_David, Flying Fox,
eagle and anyone else who tested the files.
Also thanks to charlie for the texture folder idea.