APPENDIX E 



FISH PASSAGE STRUCTURES 



PROVIDING FOR FISH PASSAGE OR CULVERT GUIDELINES 



Fish passage structures should be provided when it is necessary to cross 

 drainages. Bridges are preferable for fish passage; however, they are often 

 economically unfeasible because of the short projtct life and remoteness of 

 most floodptain gravel removal operations. If mature timber is available, 

 it may be used for effective and economical log culverts. Metal culverts, 

 although generally undesireable in temporary roads, are usually utilized, but 

 must be installed properly to provide adequate fish passage. The following 

 guidelines on fish passage structures are a synopsis of those developed by 

 Dryden and Stein (1975) and U. S. Department of Agriculture (1979) for the 

 protection of fish resources. The former document presents guidelines to be 

 considered in Northwest Territories road design while the latter deals specif- 

 ically with how to properly design fish passage structures in Alaska roadway 

 drainages. Refer to these documents for more detail and specifics. 



Hydro logical Design 



Structure Velocities. 



A. In general, the average velocity should not exceed 0.9 m/s during fish 

 migration periods. Many species require velocities considerably less 

 than this during migration periods and fish passage can be impeded at 

 velocities of 0.3 m/s (Figure E-l). 



B. A 3-day delay period (3 days of velocities in excess of those required 

 for passage) should not be exceeded during the mean annual flood 

 (2.33-year recurrence interval flood). A 7-day delay period should not 

 be exceeded in the design flood. 



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