Excessive Velocities

Water velocities can be too high to pass fish or other organisms during some or all of the year. This is a particularly relevant factor with many culverts. As stream discharge increases, velocities within culverts increase correspondingly. These velocities can easily exceed 10 feet per second, which is nearly twice that of even the strongest swimming salmonid's capabilities. In addition, flows within crossing structures are generally uniform, allowing no resting areas for aquatic species attempting to pass through them. The result is that the species must be able to swim the entire length of the structure in one burst effort.