Many existing stream-crossing structures on low-volume roads were designed and constructed to pass the design flow. Many of these structures are large-diameter metal culverts that are mechanically sound and still sufficient for the volume of traffic and the design vehicle as well as the maximum designed stream flow. However, design of these structures often gave no thought to the migration or mobility of aquatic species, particularly fish. Continued existence of many aquatic species requires that habitat fragmented by development be reconnected, specifically stream segments separated by road-crossing structures such as large culverts. The user cost-benefits and revenues available to the low-volume road manager make full replacement of existing structures prohibitive and difficult to justify, especially when the existing structure is sufficient for the traffic need. An effective, economic alternative to the removal of large culverts is offered, one that can be implemented with commonly acquired equipment and labor, with costs kept reasonably low in meeting the objective of reconnecting segments of aquatic habitat. This paper is also available on CD-ROM (see C 30152 CD-ROM).
Abstract