How to install Culverts
For guidelines on how to install culverts visit the Ministry for the Environment’s website.
Excerpt from the Ministry for Environments Culvert Guidelines:
“Allowance must be made in construction for fish passage through the culvert. The simplest way of achieving this is to make sure the base of the culvert is slightly below the streambed and that the culvert is laid on the same grade as the natural stream. As a rough guide culverts less than 600 mm should be buried 75 mm into the streambed; culverts less than 1000 mm should be buried 100 mm; and culverts larger than 1000 mm should be buried in the stream by 150 mm.”
Excerpt from Landcare’s Hooked on Fish information pack:
“Fish-friendly culverts ensure that:
- water flows slowly (< 30 cm per second)
- there are fish rest areas (e.g. rocks or smooth damp walls)
- at least 10 cm of water always flows through
- fish aren’t required to jump
Culverts fitting in with nature:
- mimic the natural streambed by following the natural slope and original streambed direction
- are wider than the stream at average flow
- are large, and never more than half full of water during spring
- are installed in late summer/early autumn after spawning and migration.”
Rip Rap armouring of waterways
For guidelines on using rip rap to prevent scouring below culverts see….
Planting for fish passage
You can find information on planting along waterways to assist fish passage and creating ideal habitats here.