The objectivate of this is to take a area and imply water on the ground. This can be done by changing a tiles texture value. I'm releasing because this knowledge could have saved me a lot of time but I couldn't find it anywhere.
In ObjectManager search for
if(tileX >= 0 && tileX < 104 && tileY >= 0 && tileY < 104)
{
Add this directly after
int absX = (k1 + tileX);
int absY = (j + tileY);
In the same method you should find something like this
if(tileType <= 49)
{
overLay[tilePlane][tileX][tileY] = stream.readSignedByte();
overlayClippingPaths[tilePlane][tileX][tileY] = (byte)((tileType - 2) / 4);
overlayClippingPathRotations[tilePlane][tileX][tileY] = (byte)((tileType - 2) + rotation & 3);
} else
Before it, we're going to put this.
if(absX >= 2679 && absX <= 2684 && absY >= 3714 && absY <= 3718)
overLay[tilePlane][tileX][tileY] = 112;