North Canterbury Fish & Game staff recently spent two weeks co-ordinating the removal of sediment from the Wairarapa Stream in western Christchurch, according to the Fish & Game New Zealand latest announcement.
During this cleanup scheme, sixty-five tonnes of accumulated silt was blasted out of the Christchurch stream, one of the Avon River’s most important tributaries.
The operation removed silt which had accumulated over the years from storm-water drains flowing into the once-pristine stream.
The goal was to make the stream suitable for trout to spawn in, and habitable by other aquatic life.
“Silt layers on top of the stream gravels had smothered the invertebrates that live in the stream bed, and by removing the sediment aquatic life has the chance to prosper again,” said Fish & Game Officer Emily Arthur-Moore.
In total, around 540 square meters of streambed near the Jellie Park Recreation and Sport Center in Ilam were cleaned. That equates to 120 kilograms of silt per square meter cleaned.
The project had planned to be carried out over a longer reach but the techniques took longer than expected.
“Various techniques were used during the two weeks, including water jet blasters, diggers and a specialized piece of equipment called a ‘sand wand’,” Ms Arthur-Moore added.
Support was given to the project by the Christchurch City Council, Environment Canterbury and Nelson-based dredging and water treatment consultants Southwater, who also provided various pumps, hoses, etc.