Forestry BMP | Stream Crossings

Avoid crossing streams when possible. 

General Guidelines:

• Cross at right angles at a point where the stream bed is straight and uniform.
• Minimize the use of equipment in the stream bed.
• Limit construction activity to periods of low or normal flow.
• Avoid prolonged activity in salmon streams during spawning periods (March 15-June 15 and July 15-Nov. 30).
• Minimize excavation and fill at stream crossings and other disturbances to stream banks and channels.
• Use materials that are clean, non-erodible and non-toxic.
• Avoid using soil as fill except when installing culverts.
• Avoid altering stream flow.
• Divert runoff from roads and trails leading to stream crossings into undisturbed vegetation. Avoid directing runoff directly into streams, including ephemeral streams.
• Construct bridge, culvert, or pole crossing at elevations higher than their road approach.
• If necessary, stabilize road and trail approaches to stream crossings with aggregate or other suitable material.
• Anchor one corner of bridge to prevent movement down stream.
• Stabilize exposed soil as soon as practicable.
• Maintain crossings in safe, functional condition.
• Close temporary crossings by removing culverts, poles, portable bridges and other obstructions as soon as crossings are no longer needed.

Bridges

General Guidelines:

• Bridges are effective ways to keep equipment out of flowing streams.
• Utilize a bridge design that will provide safe access and minimize disturbance to the stream bank, channel, and the riparian management zone.
• Use temporary or portable bridges instead of culverts to access areas where permanent structures are not needed.
• Place them so as not to unduly constrict stream channels or impede flood waters.
• Anchor temporary bridges on one end with a cable or other device so they do not float away during high water.
• Install so they can be removed easily and promptly when they are no longer necessary.
• Portable bridges may be rented through the Indiana Division of Forestry. For more information, contact Jeff Settle at jsettle@DNR.in.gov or call 812-358-2160.

Culverts

Consider using a permanent rather than a temporary culvert when the crossing is likely to be used again within 10 years. Avoid use if temporary or portable bridges are more suitable.

General Guidelines:

• Use minimum size of 12 inches in diameter and large enough to pass flood flows. See Culvert Size Guidelines.
• Use arch culverts where it is important to retain the natural stream bottom.
• Both ends should extend at least one foot beyond the edge of the fill material.
• Place in line with the natural stream course.
• Install at or slightly less than the natural stream slope.
• Compact fill material firmly around culverts, particularly around the bottom half to prevent water from seeping around the culvert.
• Cover the top of culverts with fill to a depth of 1/3 the pipe diameter or at least 12 inches, whichever is greater, to prevent crushing.
• Hollow logs are permissible in very small channels if they can handle anticipated stream flows but should be removed once they are no longer needed.
• Keep culvert open and free of obstructions.
• Use flared-end culverts or rip rap where necessary to protect culvert inlet from erosion.

Fords

Avoid using fords if practicable, especially in areas of high water quality concerns.

General Guidelines:

• Select fording sites with gentle approaches, low banks, and hard, stable streambeds.
• Construct to conform as closely as possible to the original streambed to minimize water flow restrictions.
• Stabilize the streambed and approaches where necessary.
• Stabilizing material may include: corduroy mats, reinforced concrete planks, crushed rock, rip-rap or rubber mats.
• Avoid depositing soil in the stream during ford construction and use.
• Avoid use during high water.
• Pole fords should be used carefully to maintain water flow.
• Pole fords are not appropriate for perennial stream crossings.
• Remove pole fords immediately after use.