Highway culverts may hinder the normal migrations of various trout species in wild trout streams, due to increased flow velocity, shallow water depths, increased turbulence, and perching. This can impede migrational movements, affecting the genetic diversity and long-term survival of some species. Often, the proper installation of culverts can reduce the adverse effects on fish while maintaining hydraulic efficiency. This study characterized the problems with existing culverts to develop guidelines for the future use of culverts in high-gradient streams. Installation criteria will ideally limit the use of bridges where culverts are appropriate, and eliminate the use of culverts where they would cause fish passage problems. This will reduce installation, maintenance, and retrofitting costs. Culverts can be the primary option for crossing trout streams where the following criteria are met: (1) The culvert can be placed on the same slope as that of the streambed; (2) The slope of the stream is less than 3%; (3) The flow velocity does not exceed 1.2 m/s under normal flow conditions; and (4) The barrel of the culvert can be properly countersunk at the outlet to prevent perching. Where the criteria cannot be met, bridges should be used. Also, baffles should not be used to control streamflow velocities in new culverts, and concrete aprons should not be used at culvert outlets. If culvert bottoms could be cast to have a roughness coefficient equal to that of the streambed, this would allow greater use of culverts at stream crossings without impeding the passage of trout.

  • Record URL:
  • Supplemental Notes:
    • The title page indicates that this is a Federal Highway Administration (FHWA) funded study, but the documentation page does not indicate this and does not assign an FHWA report number.
  • Corporate Authors:

    Virginia Transportation Research Council

    530 Edgemont Road
    Charlottesville, VA  United States  22903

    Virginia Department of Transportation

    1401 East Broad Street
    Richmond, VA  United States  23219

    University of Virginia, Charlottesville

    Center for Transportation Studies, P.O. Box 400742
    Charlottesville, VA  United States  22904-4742
  • Authors:
    • Fitch, G M
  • Publication Date: 1995-10


  • English

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 24 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00720214
  • Record Type: Publication
  • Report/Paper Numbers: VTRC 96-R6, Proj No. 3042-010
  • Created Date: Apr 18 1996 12:00AM