Idaho Land Conservation Assistance Network

Culverts are the most commonly used form of stream crossing. The following tips will enable you to construct a well-functioning and stable culvert.

• Provide a suitable bed for the culvert composed of compactable material.
• Compact fill around and over the culvert in 1-foot lifts.
• The fill above the culvert must be 12 inches of 0.5 times the diameter of the culvert, whichever is greater. For example, a 20-inch culvert must have 12 inches of fill above the pipe, while a 40-inch culvert will need 20 inches of fill above the pipe.
• Apply armoring or vegetation around culverts to prevent erosion, as needed.

For more information about culvert installations, see:

• IDL Forester Forum Forest Practices No. 12 – Fish Passage Guidelines When Installing Stream Crossings.
• IDL Forester Forum Forest Practices No. 14 – Correctly Classifying Streams to Protect Fisheries and Domestic Water Supplies.