Impact of infill on our streams

North Shore City Council is reviewing what impact existing and future infill housing will have on its stormwater network and the city’s streams.

More impervious (hard) surfaces from infill development can create stormwater problems by preventing rainwater from soaking into the ground. Flooding, erosion and contaminants in stormwater are more likely, and the changing levels of streams can damage the habitats of fish and other species.

The council will look at areas where stormwater overflows are common to determine whether the current controls in its District Plan are adequate. The density of development, minimum lot sizes, maximum areas of impervious surfaces and further upgrading of the stormwater network will be considered, as well as community education programmes. The District Plan currently requires that a minimum of 30 per cent of each site has a permeable surface such as grass or gravel, allowing natural drainage. Before any changes are made the council will consult with the local community.

North Shore City’s strategy and finance committee chairperson, Tony Holman welcomes an integrated and consultative approach to addressing how development is impacting the city’s stormwater network and streams.

"We have a great quality of life and live in a beautiful city that must be protected. We all need to be active in maintaining that," he says.

Tony Holman says his council wants to encourage people to use permeable surfaces where possible. "We should look carefully at how we design our driveways, decks and outdoor areas so that rainwater can naturally feed into the ground and streams," he says.

"It’s also important to minimise our water use and reuse it through rain tanks if we can."

North Shore City Council has more information now about the city’s streams and the capacity of its stormwater system than when the District Plan was first produced in 1994. This information will used in the review and during consultation.

The review is just one of a wide range of projects outlined in the council’s recently released City Blueprint Action Plan designed to meet the challenges of growth and change. Further reviews looking at how infill development impacts the wastewater (sewerage) network and suburban character areas are also planned.

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