NIWA initiates new information system for urban stormwater quality

Urban runoff is a major source of contamination for streams and estuaries, and can result in the accumulation of metal and organic contaminants in sensitive environments.

Urban runoff is considered non-point source pollution: that is, although it may be discharged via a pipe or from overland flow, there can be hundreds of discharge points in any catchment. This, along with the intermittent nature of runoff flows, makes it difficult to monitor in the field and in many cases literature data is used as a proxy. However, it is difficult to identify where literature data, often based on international studies, is relevant to New Zealand.

A wealth of water quality data in urban runoff has been collected in New Zealand over the last two decades by some Councils, research institutes and universities and this has led to significant progress in our understanding of contaminant sources and loads. However, much of this valuable information is not publically accessible, only being reported in summary format or remaining in organisations' files. However, in some regions of New Zealand there has been only limited monitoring of urban runoff to date.

It is clear that a greater understanding of urban runoff quality can be made through integration of data gathered throughout New Zealand.

A new project developed by NIWA aims to provide stormwater managers, regulators, environmental consultants and researchers with access to relevant and meaningful stormwater quality data. We have developed a pilot database of urban runoff quality data that is currently being extended into a web-accessible nationwide database.

The database collates urban stream and stormwater quality information in a single location, allowing interpretation of urban runoff quality data from throughout New Zealand. It will enable analyses of variations in runoff quality by characteristics such as primary land-use, geographic area and the type of stormwater treatment (if any). Summary data produced using this tool will provide useful comparisons for individual stormwater assessments (e.g., by councils), could be used where data cannot be collected or where monitoring is considered too expensive, and could be used to support resource consent applications for urban development.

We are now seeking urban runoff data from all over New Zealand to add to the database to ensure national coverage. This may include stormwater research studies, monitoring studies or consent data.

If you are interested in contributing to this project please contact Jenni Gadd, jenni.gadd@niwa.co.nz, or Jonathan Moores, jonathan.moores@niwa.co.nz, of the Urban Aquatic Environments Group, in NIWA's Auckland office. 

Contaminated stormwater discharging into an open stormwater drain (Pete Pattinson, NIWA)