The Lower Waitohu Stream project aims to address the flood risk in the Rangiuru and Bennetts/Convent Road areas. The project is being undertaken by Greater Wellington Regional Council and could involve measures such as clearing areas on the banks and in the channel of the lower Waitohu Stream to reduce blockages in a flood event, widening the stream channel in some areas, and constructing the South Waitohu and Convent Road stopbanks.
Consultation has been ongoing with directly affected landowners and the wider community. The plan will take into account Kapiti Coast District Council’s stormwater work as part of the Greater Otaki project.
Why is this work being done?
The Waitohu Stream has caused damage to houses and property in the Bennetts/Convent Road areas during relatively small floods events. During larger flood events, considerable damage would also result to properties in the Rangiuru area. This project aims to reduce the threat to these properties through a combination of measures.
The Otaki Floodplain Management Plan (OFMP), developed in 1998, included outcomes for the management of the Waitohu Stream area, including planning controls, the South Waitohu Stopbank, house raising, bridge raising and constructing a stopbank at Convent Road.
The Waitohu Stream study (2006) expanded on the ORFMP, in particular the flood and erosion hazard in the Waitohu Stream. The study made a number of recommendations for ongoing management, such as continuing the use of planning controls to mitigate the flood risk, clearing some streamside vegetation to reduce obstructions in the stream and undertaking further detailed studies on the Bennetts/Convent Road flooding.
During consultation on the South Waitohu Stopbank in 2009 (an outcome of the OFMP), it became clear that the community was concerned that any future stopbank should not significantly exacerbate flooding in other areas. KCDC also wanted the project to be integrated with important stormwater works.
Cutting the Waitohu Stream Mouth Cutting
The stream mouth moves naturally and this can cause dune-erosion and upstream flooding. On occasion the mouth of the stream is 'cut' mechanically. For more about this go to the Waitohu Stream Mouth Cutting Information Sheet.