The upgrades will enhance water quality, create a healthier aquatic habitat and stabilise the banks along the Fendalton Park stream.
The section of the stream runs along the south of the park, starting near Medbury Tce and winding along the Fendalton Bowling Club.
Work began last week and will continue until the end of October.
Waimairi Stream is a tributary of the Ōtākaro Avon River, flowing from Burnside Park and connecting with Wairarapa Stream before meeting the river at Mona Vale.
Boulder and cobble clusters will be placed in the stream to enhance flow diversity.
Native vegetation will be planted along the banks to reduce sedimentation and erosion, and improve natural biodiversity.
The section of the stream is home to native shortfin eels, longfin eels and upland bully, plus introduced brown trout.
Further waterway works upstream near Daresbury Park are continuing, with enhancements to a section of Waimairi and Fendalton streams.
Old timber linings will be replaced with new timber and rock linings. Native riparian plants will be put in, as well as fish hides.
Enhancements at the Waimairi/Fendalton streams section will be completed in late November.
