Nature-Like Fishways (NLFs)

In their 2016 publication the National Oceanic and Atmospheric Administration (NOAA) has highlighted many advantages to designing fish passage that is more nature-like and less structural.

“NLFs (nature-like fishways) also provide greater surface roughness and flow complexity than typical technical (or structural) fishways (e.g., Denil, steep‐pass fishways), creating attractive flow cues to passing fish. Interstitial spaces and surface irregularities associated with NLFs also provide cover and spawning microhabitats, which may be particularly important in watersheds where these specific habitats are limited. The use of natural materials in NLFs such as fieldstone boulders and cobble is also beneficial in lessening the likelihood of fish injury from sharp‐edge structures such as those typically associated with structural fishways. NLF designs such as partial or full‐river width or bypass channels around barriers can result in effective passage if appropriately designed and constructed for passing fish over a wide range of flows throughout the anticipated seasonal run period for a target species or run periods for targeted fish species assemblage.” Page – 2

An example of a NLF in Saco Maine. These are always custom designed to best fit the local conditions and fish being accommodated.

A description of how a nature-like fishway works. An important option for balancing the needs of hydro and fisheries on the Androscoggin.