National inventory and assessment procedure for identifying barriers to aquatic organism passage at road-stream crossings

Publication Date



barriers, streams, manual, migration, restoration, transportation, ecosystems, watershed, habitat

Report number

National Technology and Development Program Transportation Report No. 7700

Publication place

San Dimas, CA


United States Forest Service


This inventory procedure is designed to be a nationally applicable, consistent method of identifying crossings that impede passage of aquatic organisms in or along streams. It is a how-to manual for approaching answers to two questions raised in United States Department of Agriculture (USDA) Forest Service Roads Analysis, [1999, p. 67, AQ(10)]: "How and where does the road system restrict the migration and movement of aquatic organisms; what aquatic species are affected and to what extent?"Full answers to these questions are essential to managing roads and planning for restoration. A transportation plan must consider and be designed to mitigate the road network's effects on aquatic ecosystems and their continuity. And planning for restoring watersheds and setting priorities cannot logically proceed without considering how fragmented the aquatic habitat is and how important it is relative to the suite of restoration needs of the whole watershed.

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