Oregon Department of Forestry

Rule Rule 629-625-0320
Stream Crossing Structures


Operators shall design and construct stream crossing structures (culverts, bridges and fords) to:


Minimize excavation of side slopes near the channel.


Minimize the volume of material in the fill.


Minimizing fill material is accomplished by restricting the width and height of the fill to the amount needed for safe use of the road by vehicles, and by providing adequate cover over the culvert or other drainage structure.


Fills over 15 feet deep contain a large volume of material that can be a considerable risk to downstream beneficial uses if the material moves downstream by water. Consequently, for any fill over 15 feet deep operators shall submit to the State Forester a written plan that describes the fill and drainage structure design. Written plans shall include a design that minimizes the likelihood of:


Surface erosion;


Embankment failure; and


Downstream movement of fill material.


Prevent erosion of the fill and channel.


Operators shall design and construct stream crossings (culverts, bridges, and fords) to:


Pass a peak flow that at least corresponds to the 50-year return interval. When determining the size of culvert needed to pass a peak flow corresponding to the 50-year return interval, operators shall select a size that is adequate to preclude ponding of water higher than the top of the culvert; and


Allow migration of adult and juvenile fish upstream and downstream during conditions when fish movement in that stream normally occurs.


An exception to the requirements in subsection (2)(a) of this rule is allowed to reduce the height of fills where roads cross wide flood plains. Such an exception shall be allowed if the operator obtains approval of a plan for an alternate practice. The State Forester will approve such a plan when the plan demonstrates:


The stream crossing site includes a wide flood plain; and


The stream crossing structure matches the size of the active channel and is covered by the minimum fill necessary to protect the structure;


Except for culvert cover, soil fill is not placed in the flood plain; and


The downstream edge of all fill is armored with rock of sufficient size and depth to protect the fill from eroding when a flood flow occurs.

Last accessed
Jun. 8, 2021