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Mini-Hydro Intake Weir

Hi everyone

Below is a photo showing modifications to a back-country mini-hydro intake weir.

The original fish pass and minimum residual flow devices were not functioning.

The new design successfully allows expected species, all of which are climbers – longfin eels, and some migratory galaxiid along with invertebrates, to migrate upstream.

Minimum flows are directed down the fish passes either side

The fish passes comprise a flexible rubber channel (2 x Flexi-baffles) lined with looped mussel-rope. The rope is only attached at the upstream end to avoid debris jams.
The Minimum residual flow is controlled by another flexible baffle that pushes water to sides before overtopping.
Please contact the Fish Passage Action Team for more detailed information.

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Focus On Maintaining Fish Passage During Low Flows

It is worth remembering that lows flows and shallow water are challenges to migrating fish. 
The video below represents remediation to an upgraded urban storm water pipe serving a small tributary of the Maitai River near Nelson, NZ.

The upgrade involved upsizing the pipe and removing the perch at the outlet.

– Base flows of the tributary are approximately 1L/S
– Pipe length 300M
– Pipe gradients range from 2%-12%

You will see an increase in the depth and width of the water along with bed-material beginning to accumulate.

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Reservoir Video

Below is one of Tim’s videos featuring the culvert remediation project in the recently published “Lessons Learnt 8”.

There is some great underwater footage showing how fish navigate upstream utilizing the back-eddies and rest pools created by the flexible baffles.

For those that missed the write-up check it out here
https://www.doc.govt.nz/globalassets/documents/conservation/native-animals/fish/fish-passage/lessons-learnt-case-studies/lessons-learnt-008-installation-of-flexi-baffles.pdf

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Lessons Learnt 8

The NZ Dept Conservation Fish Passage Advisory Group website has a number of Lessons Learnt describing different fish passage remediation projects.

Tim Olley spent over a year researching and putting together this comprehensive report highlighting the effectiveness of flexible baffles in a long, steep culvert.

We are planning to make a PowerPoint and/or video of this report at some point.

Enjoy.

Click here to view Lessons Learnt 8

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Keep Up The Good Work

Shane Scott has put together this short video showing some low cost fish passage remediation projects across North America.

Note the different configurations used to suit each site.

Also enjoy the great commentary with the Johnson Creek segment. 

Contact Shane directly for more info – ph number at end of video.

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Brook Channel

Restoring fish passage is great, but don’t forget about the habitat!
In natural environments, overhanging vegetation is important for shade, refuge and a food supply, but also helps fish migrate up along the edges of waterways.
This video shows a trial project funded by Nelson City Council, where PlanterPods and Flexi-baffles are working together to provide habitat and passage, along a section of heavily modified urban stream in New Zealand.
 

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Box Culvert Remediation For Fish Passage

Please take a minute to watch this short video showing the effects of flexible baffles fitted to the invert of a box culvert.
This is a newly installed culvert (replacing an old smaller round one) under a public road in the Bay of Plenty, New Zealand.
It is hoped that over time, smaller bed-material will accumulate among the large rip-rap and between the baffles, creating a more natural habitat.
Also watch out for the juvenile galaxiid (whitebait) that were seen, just a few days after the installation, making use of the baffles to migrate upstream. Enjoy!

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Fish Passage

Chuck Lobdell and the team at Johnson Creek Watershed OR have recently installed some flexible baffles in the culvert under Highway 26.
The aim is to improve fish passage in all flow particularly for spawning salmon.
The baffles are offset to provide a low-flow swim channel and also extend up the wall of the culvert to assist during higher flows.