Most rivers have at least one place at which they can be crossed, such as a bridge or a ford. Such crossing points should normally be treated as open terrain, but only if the unit attempting to use the crossing point is in a narrow enough formation to fit across, otherwise treat the entire unit as being in the river! Whether or not a unit is narrow enough will normally be fairly clear.
Source: Warhammer Fantasy: 8th Edition
Bridges and Other CrossingsURL Copied!