Addington Brook – A Catchment Approach to Improving the Health of an Urban Waterway

Worldwide urban streams face a multitude of environmental pressures that are now routinely summarized using the term ‘urban stream syndrome’ that was coined by Meyer et al (2005). The term describes the consistently observed ecological degradation of streams draining urban land.

This paper shares the journey of proactively enhancing one such urban stream in Christchurch, namely Addington Brook, a priority focus for Christchurch due to its degraded water quality. The story includes an honest account of the challenges, successes and opportunities of urban catchment improvement programmes. It highlights the principles of the approach and key steps taken in the early days, how this approach has evolved and what is planned for the future.

Addington Brook is a spring and stormwater-fed waterway that meanders through the south west of Christchurch and drains into the Ōtākaro / Avon River near the hospital and Botanic Gardens. Along its course it is mostly hidden underground, travelling through an extensive network of stormwater pipes (> 3.2 kilometers) before daylighting when it reaches the iconic Hagley Park. Features within the Addington catchment are typical of commercial and industrial land use. There are high percentages of impervious surfaces in the form of roads, roofing, carparks and pavements. Many roads are of high intensity use and a large proportion of the industrial roofing consists of zinc galvanised materials.

In 2014, the Christchurch West Melton Water Zone Committee1 identified Addington Brook as one of several priority catchments to focus on remediating. This was mainly due to poor water quality shown by long-term stream monitoring and its negative impacts further downstream on the Ōtākaro / Avon River. Historically there had also been several significant environmental incidents resulting in fish kills through the Hagley Park section, for which the source was unfortunately not identified. Staff from Environment Canterbury were then tasked broadly with improving the health of this urban waterway, with modest resources and a knowledge that the problems evident were complex.

This paper outlines the deliberate focus taken since 2014 on reducing our catchment knowledge gaps, partnering with key stakeholders and building relationships, raising awareness of the waterway, engaging with individuals, schools and businesses to be part of the solution and importantly working with research organizations to support them in pioneering projects to help address the environmental challenges in the catchment.