Waterway Management in Christchurch

In the early years of the settlement of Christchurch the land was swampy and it was an unhealthy place to live. The Christchurch Drainage Board (CDB) was set up to manage the drainage of the city. Serious floods made life in the winter hazardous for those living in the low lying parts of the city. Water borne diseases at times reached epidemic proportions. To improve the efficiency of the water flow and to protect and retain the banks the CDB timbered the sides of many streams and drains. With the improved drainage over the city as a whole the risk of flooding was greatly reduced. The Christchurch City Council took over the work of the CDB in 1989. A growing environmental awareness and the enactment of the Resource Management Act (1991)resulted in a new approach to waterway and wetland management. Timber linings are now being replaced with naturalised banks without losing the drainage benefits already achieved. Today the Parks and Waterways Unit oversees the management of waterways and wetlands in the Christchurch area.

For years I lived near a drain which had been boarded and also fenced to keep safe the children who played in the adjacent park land. No restoration of the drain to natural boundaries or beautification of the park had been organised until under the new policy the boarding was removed, the course of the drain was changed, the banks sloped and planted with native vegetation.

The factors/philosophy behind present waterway management Waterways, Wetlands and Drainage Guide produced by the Christchurch City Council describes the current philosophy guiding waterways management. “Today’s management responds to the expectations of communities with regard to wise resource management and the values associated with water environments. These values have been identified as ecology, landscape, recreation, heritage, culture, and drainage.”

Decisions about land use are also influenced by natural hazards, contamination of surface and ground waters, and natural processes.

As Christchurch has over 360 kms of open waterways and over 50 wetlands there is great scope for the application of the new policy and long term visions have been developed for each of the fourteen project areas into which the city has been divided.

The Waimakariri River Research into the changes in the course of the Waimakariri River has shown that long ago it flowed through the Kaiapoi area, then spread right across the plains to Lake Ellesmere/Te Waihora, creating saltwater wetlands and small meandering waterways which became home to numerous birds, fish and invertebrates. Maori inhabitants used some parts of the waterways for travel, ritual and food, but the European settlers who followed were concerned with developing land for farming and waterways were piped or turned into channels for faster water flow.

Wetlands and Ponds in the Christchurch area The term Wetlands is defined in Waterways, Wetlands and Drainage Guide as “permanently or intermittently wet land, shallow water and land water margins.”

Wetlands may be freshwater as in the Travis Wetland, swamp forest as in Riccarton Bush, or estuarine like the Brooklands Lagoon.

Ponds which are pools of still water are typified in the Christchurch area by:

• Horseshoe Lake which is formed by the Avon/Otakaroro River
• the ponds specially created in the Christchurch Botanic Gardens and in Janet Stewart Reserve because of their aesthetic and wildlife values
• Westlake Reserve pond which was a shingle quarry
• Bromley Oxidation Ponds which treat effluent from the waste water treatment plant before it is discharged into the Avon-Heathcote estuary.

They are an important habitat for wildlife.

Planting to create habitats for native birds, fish and invertebrates Overhanging vegetation shades waterway and wetland margins and supplies food, shelter, and breeding sites for birds, fish, and invertebrates.

106 species of birds have been recorded in the Christchurch area since 1980, 76 using the waterways, wetlands and coastal habitats. These include the New Zealand Shoveler, New Zealand Scaup, South Island Oystercatcher, Variable Oystercatcher, Eastern Bar-tailed Godwit, Red-billed Gull, and White Fronted Tern.

There are ten species of native freshwater fish found in the Christchurch and six are considered common.

Inanga, adult whitebait, are found in slow-flowing parts of the city’s rivers and in Travis Wetland.

Heritage values important in the restoration process Care is taken to preserve brick and stone work which are part of old bridges and culverts, historic sites like wharves and watering places for horses, and pa sites and other places important to Maori for food gathering and canoe portage.

The issues important to the tangata whenua are considered in the planning of changes to the waterways. Water is viewed by Maori as a sacred and a practical asset. It played a significant part in sacred rites and improving the quality of water is seen as important by Maori resource managers.

Drainage It is essential to keep sufficient land adjacent to waterways to allow space for storm flows and natural drainage processes to occur. It also enables many other values to be realised including the planting of green corridors that allow bush birds to move in around the city.

Checklist for use in planning restoration of a waterway The checklist for planners in this work includes looking at the existing ecology of the area, the landscape and the community’s perception of it, recreation uses, the cultural values, the heritage, the drainage, the safety of people using the area, hazards, legal aspects and maintenance.

Restoration of the Riccarton Main Drain in the Paeroa Reserve Here some of the key factors included providing safe access to the area, removing the boarded sides of the drain, creating a new meandering course for the stream, developing sloping banks, creating a duck pond, planting riparian vegetation using local native plants, and creating a safe area for recreation for people of all ages. Plunket Rooms and a children’s playground are close to the stream so the depth of the water and access to it had to be considered.

The final design included piping of the stream for some distance from Rattray Street to allow access to one property and to the Paeroa Reserve from the east, and creating a meandering stream bed, a bridge across the water,and a pond with broad steps providing a place to sit and to feed the ducks.

This plan required the use of heavy machinery to pipe the eastern section and establish the new course for the water in the reserve.

The final transformation is a delight to residents in the area and others wanting a place to walk or to picnic.

The change from a park which looked like a paddock with a deep fenced drain across it to an attractive and welcoming reserve so impressed me that I wanted to know more about the new Christchurch City Council Policy on waterways. Bus trips beside the city’s major rivers with a commentary on the history of each area and the vision for development helped me to gain further knowledge. These trips are offered to groups and one tour is offered to the public each year.