The majority of man-made stream crossings such as bridges and culverts in British Columbia pose a "serious impediment" to migrating fish because of bad engineering, a new study by the Forest Practices Board reveals.
The board investigated 1,100 road crossings of streams in 19 watersheds around the province and found that only 42 per cent of the crossings are sufficiently well-designed to allow salmon, trout and other fish to swim above the crossings.
The report said some streams were in better shape than others -- on the watersheds that were studied, chances that fish could migrate past crossings ranged from as high as 94 per cent to as low as 20 per cent.
Although streams with prime habitat fared better in the study than those with marginal habitat, there was still a 28 per cent chance that a crossing on a good stream would present a barrier to fish.
Stream crossings developed for forest roads were identified as primary culprits, but construction for highways, farms and residential developments are also threats, the report said.
It said closed-bottom structures, such as culverts, were identified as posing the greatest obstacles.
"Road crossings constitute a widespread risk to fish passage in these watersheds, especially when closed bottom structures are used," the report said.
"Enforcement of legislative requirements to ensure fish passage is an issue and enforcement agencies do not currently agree on what constitutes a material adverse effect on fish passage and how to assess and enforce its maintenance."
The report questions whether the federal and provincial governments have ever taken a serious interest in the problem, and urges the province to take quick action to address it.