Waiutuutu/Okeover Stream
Between 1999 and 2005 the restoration of UC waterways have focused on the Waiutuutu/Okeover Stream because of its high restorative potential and much of its length lies within the campus boundaries. Restoring in-stream habitat in particular has been a priority.
The Ephemerals
The Ephemerals reach is the very top section of Waiutuutu/Okeover Stream, emerging from stormwater pipes near Waimairi Rd and running alongside Ilam Fields to just below Ilam Rd. This section receives stormwater from the surrounding suburban catchment and only flows when it rains. Part of the section is piped, part is confined within wooden retaining walls, and part is bare open channel.
Two issues have been identified in this section of stream that could be potentially limiting the downstream aquatic community, particularly in the headwaters:
- Poor quality of stormwater runoff from the suburban catchment.
- Large quantities of leaves entering the stream in autumn, reducing dissolved oxygen levels as they decompose.
Recent research by staff and students in the Natural Resources Engineering programme have determined the types and levels of stormwater contaminants entering the ephemerals reach. This research, which was supported by the Christchurch City Council and Environment Canterbury, is now being used to develop practical stormwater filtering solutions.
The Headwaters 2003
UC worked in partnership with Christchurch City Council on this significant project. The 130 metre headwaters reach was developed with the aim of translocating Canterbury mudfish (Neochanna burrowsius), a small, threatened fish species endemic to and once widespread in Canterbury streams and wetlands. Waikōura (freshwater crayfish) were also reintroduced.
headwaters poolLarge willows and hawthorn, which previously dominated the site, were removed and parts of the channel were realigned and excavated to establish a greater connection with ground water springs. Four narrow, deep pools were created to provide specialised habitat for mudfish. A series of large deep sediment-trap pools and reed beds upstream were created to protect the habitat pools from sedimentation.
Over 2500 plants belonging to 70 native species were planted along riparian areas to recreate vegetation patterns likely to have been present prior to European settlement.
The headwaters project received a gold award in sustainability at the 2004 New Zealand Landscape Architecture awards and won the Australasian Campuses Towards Sustainability award for on-going projects in Adelaide in 2011.
The reintroduction of Canterbury mudfish and Waikōura was not successful. Mudfish were possibly predated by long-finned eel, and Waikōura were probably killed by an acute pollution event.
The Wetlands 2001
The previously stagnant, over-wide Engineering pool was developed in 2001. Boulders, sunken kahikatea and totara logs (found under the campus during building constructions), gravel islands and beaches, and aquatic planting were used to manipulate channel width, water level and flow velocity. Eco-sourced wetland and kahikatea swamp forest plantings as well as dry terrace plantings were established in natural associations not only to improve riparian and aquatic habitat, but also the quality of the landscape amenity in adjacent high-use areas.
The Riffle Runs 1999-2000
Okeover Stream rifflesA 60 m reach alongside the Department of Electrical Engineering was re-vegetated using eco-sourced indigenous plant species in 2000. Rocks and salvaged ancient native kahikatea and totara logs were placed strategically in the stream to increase habitat diversity and alter flows. The goal was to increase oxygenation of the water and facilitate the flushing of fine sediment to expose the gravel streambed.
The Meanders 2005
Restoration of Waiutuutuu/Okeover Stream meanders behind Forestry School, Macmillian Brown Library and Te Ao Marama was an opportunity to build upon the success of previous Waiutuutu/Okeover Stream projects. Developments in this section included altering the stream bed and planting the stream banks to improve aquatic and riparian habitats, planting native species of ethnobotanical importance, and enhancing the threatened plants collection behind the School of Forestry.