Stream-Simulation Group, Forest Service . 2008. Stream Simulation: An Ecological Approach to Providing Passage for Aquatic Organisms at Road-Stream Crossings. 0877 1801P. San Dimas, CA: U.S. Department of Agriculture, Forest Service, San Dimas Technology and Development Center.
This is a guide to stream simulation—a method for designing and building road-stream crossings intended to permit free and unrestricted movements of any aquatic species. The guide aims to help national forests achieve their goal of maintaining the physical and biological integrity of the stream systems they manage, including existing populations of fish and other wildlife species (see National Forest management Act, 16 U.S.C. 1600-1616). Habitat fragmentation is an important factor contributing to population declines of many fish, and crossing structures that are barriers are a large part of the problem. Stream simulation provides continuity through crossing structures, allowing all aquatic species present to move freely through them to access habitats, avoid adverse conditions, and seek food and mates. Stream simulation applies to crossing structures on any transportation network, including roads, trails, and railroads. For brevity, the guide refers to all of these types of transportation infrastructure as ‘roads.'