This page on stormwater results from a 1998 report prepared for the Ministry. The page remains on our website for information purposes only. Some of the information contained in the report may now be out of date.

Land transport effects on aquatic ecosystems

In 1996, the Ministry released a discussion paper on environmental externalities as part of the Land Transport Pricing Study. The Ministry reported that the contribution of road run-off to the flux of contaminants to freshwater and marine environments was unclear. Road run-off was however, considered to account for 40-50% of urban metal contamination to aquatic ecosystems. It was considered at that time that although effects on water quality and associated aquatic ecosystems was one of the key potential impact areas of road transport, research about the environmental effects of road transport on water quality was not well advanced. This resulted in an inability to quantify the contribution that road transport made to any specific effects.

The 1996 discussion document identified effects on water quality and associated aquatic ecosystems as one of the key impact areas of road transport. Work by the Ministry for the Environment subsequently identified motor vehicle emission discharges via stormwater as a key effect issue in relation to freshwater, estuaries and coastal areas.

In 1998, a series of reports was produced by Kingett Mitchell Limited, in association with Fuels and Energy Ltd, for the Ministry of Transport that examined the effects of contaminants derived from road transport on aquatic ecosystems in a New Zealand context wherever possible. The series of reports aimed to provide an overview as to what was known at that time about the effects of the contaminants released by motor vehicles. As such, the assessments were dependent upon what was known about contaminants emitted by motor vehicles to aquatic ecosystems in the late 1990s.

As outlined in this series of reports, the stormwater from roads in most locations does not just transport the contaminants generated by motor vehicles. Roads are typically surrounded by other activities that have a significant influence on the nature of runoff from various land uses.

The full series of reports prepared as part of this 1998 study by Kingett Mitchell Limited for the Ministry of Transport are listed on the right hand side of this page.