muddy Mississppi River

A quick question.
I'm getting ready to use FS2k2 to make a little computer movie about my first flight, which was in a DC-7 in 1958.
One of the scenes will involve flying over the Mississippi river.
My question: If I want to change the Mississppi from blue to muddy brown - is that a simple matter of changing a few water textures- or will it be more complex than that ?
I'm getting ready to use FS2k2 to make a little computer movie about my first flight, which was in a DC-7 in 1958.
One of the scenes will involve flying over the Mississippi river.
My question: If I want to change the Mississppi from blue to muddy brown - is that a simple matter of changing a few water textures- or will it be more complex than that ?