Editing Culvert (section)

==Environmental impacts==
[[File:Aquatic Organism Passage Culvert.jpg|thumb|right|This culvert has a natural surface bottom connecting wildlife habitat.]]

Safe and stable stream crossings can accommodate wildlife and protect stream health, while reducing expensive erosion and structural damage. Undersized and poorly placed culverts can cause problems for water quality and aquatic organisms. Poorly designed culverts can degrade water quality via scour and erosion, as well as restrict the movement of aquatic organisms between upstream and downstream habitat. Fish are a common victim in the [[loss of habitat]] due to poorly designed crossing structures.

Culverts that offer adequate aquatic organism passage reduce impediments to movement of fish, wildlife, and other aquatic life that require instream passage. Poorly designed culverts are also more apt to become jammed with sediment and debris during medium to large scale rain events. If the culvert cannot pass the water volume in the stream, then the water may overflow the road embankment. This may cause significant erosion, ultimately washing out the culvert. The embankment material that is washed away can clog other structures downstream, causing them to fail as well. It can also damage crops and property. A properly sized structure and hard bank armoring can help to alleviate this pressure.

[[File:Aquatic Organsim Passage Culvert Replacement.jpg|thumb|right|Aquatic organism passage compatible culvert replacement in Franklin, Vermont, just upstream from Lake Carmi]]

Culvert style replacement is a widespread practice in stream restoration. Long-term benefits of this practice include reduced risk of catastrophic failure and improved fish passage. If best management practices are followed, short-term impacts on the aquatic biology are minimal.<ref>{{cite journal |vauthors=Lawrence, JE, Cover MR, May CL, Resh VH |title=Replacement of Culvert Styles has Minimal Impact on Benthic Macroinvertebrates in Forested, Mountainous Streams of Northern California |journal=Limnologica |year=2014 |volume=47 |doi=10.1016/j.limno.2014.02.002 |pages=7–20 |arxiv=1308.0904}}</ref>