Evaluation of Longrie-Fectau fish passage structure

Evaluation of Longrie-Fectau fish passage structure

Abstract: Connectivity is critical for freshwater fish conservation, and the design of fish passage structures is a tradeoff between the space available for construction, slope, and costs associated with the structure. The Longrie-Fectau fish passage structure was designed to be modular, readily deployable, and site-generic. To accomplish this, it was designed as two prefabricated portions (straight and curved) that can be quickly installed and accommodate various barrier heights by adding or removing sections. Additionally, the length of straight sections can be altered to fit any site. The sinuous passage design allows a relatively low grade (2%) and passage over large structures with short apron space. The individual pre-cast costs were $9,000 for each of the straight sections, and $6,000 for each of the curved sections. The foundation required to support the pre-cast sections was approximately $4,000 per section. Other financial considerations that will vary depending on the site include the passage entrance and exit, the cap to limit sheet flow over the passage, diverting and dewatering the creek during construction, and additional foundation construction to support the pre-cast sections. We evaluated fish passage through this structure in Fountain Creek, Colorado via a PIT tag mark-recapture study. We documented four Great Plains native fish species successfully ascending the passage structure, with most passage occurring at night. We estimated a 3% probability of a released fish encountering the first array, indicating attraction flows are important consideration for passage design. However, once in the structure, there was a high probability of complete passage (89%). Although this particular structure is large (123 m), passage was relatively fast once fish entered, with median time of successful ascent of 19 minutes and fastest successful passage of six minutes. While fish passage often requires site-specific engineering and design, the Longrie-Fectau-style fish passage design is an option that may reduce construction costs due to its modularity and simplicity.

Fitzpatrick, Ryan

Longrie-Fectau fish passage structure

19:37

2022-03-05

English

Aquatic Research Presentations

http://youtu.be/Wi3tx1WdLd4

2022-03-05T15:29:47Z

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