Land Drainage

Land Drainage What is the Land Drainage activity and why is the Council involved? The common purpose of land drainage and flood protection and control activities is to retain the productive capability of land, therefore these activities are incorporated into one Land Drainage activity. It is believed that Land Drainage is an appropriate name for this activity, as it is easily understood by those who are affected. The legislative requirement for the Flood Protection and Control activities is set out in section 2 of schedule 10 of the Local Government Act, 2002. Land Drainage is a particularly significant activity for Hauraki District Council, more so than for most other local authorities in New Zealand. The Council has Land Drainage standing committees that have representatives from both the Council and users; these committees advise the Council on land drainage and flood protection and control matters. Land drainage and flood protection and control are key functions of the Council’s operation, as a considerable portion of the northern Hauraki Plains lies at or below the normal high tide level in the Firth of Thames. The remainder of the land on the Hauraki Plains is only slightly above this level, so protection against high water tables, extreme weather events, high tides and river floods is essential to the continuing occupation and use of the land for residential, agricultural and horticultural purposes. Flood Protection Flood protection in the Hauraki District is provided by the river schemes of the Waikato Regional Council, except in the northwest part of the District (Waitakaruru to Miranda) where it is provided by Hauraki District Council. The assets that provide direct protection from river and tidal flooding include stopbanks, floodgates and pump stations, and are referred to as primary flood protection assets. Land Drainage Land drainage assets collect runoff from the catchment areas of the District and lead it to the primary flood protection assets which discharge it direct to river or sea outlets. In addition to the drainage network, land drainage assets can include stopbanks, floodgates and pumps. The latter drainage assets perform a land drainage function, e.g. pumping from a minor drain into a major drain; they do not provide direct protection from river and tidal flooding, and are referred to as secondary protection assets. These services are provided by the Council in four Drainage Districts: The Western Plains Drainage District - situated between the Piako River and State Highway 27, from the Firth of Thames to the District boundary with Matamata-Piako District Council. The Eastern Plains Drainage District - situated between the Piako River and the Waihou River, from the Firth of Thames to the District boundary with Matamata-Piako District Council. The Paeroa Rural Drainage District - comprises three smaller, former drainage districts east of the Waihou River. The former districts were the Komata North, Opukeko and Tirohia Rotokohu drainage districts. Taramaire Drainage District - a small drainage district south of Kaiaua that the Council became responsible for as part of the Auckland City re-organisation. The Land Drainage activity provides for public safety and effective protection of property, farmland and roads by draining excess surface water and managing ground water levels. The activity delivers sustainable services which the community needs to function productively and comfortably on a day to day basis, which meet high community health and safety standards, and which promote continuing productive use of the land. How does the Council provide the Land Drainage activity? The Council performs the Land Drainage activity by maintaining drains, canals, control structures, floodgates, flood pumps, culverts and stopbanks. Maintenance of the drains ensures that the agreed level of service is achieved by effective performance of the drainage system in removing surface runoff. Council drains are maintained by a combination of spraying and machine cleaning programmes, conducted by the Council’s Construction and Maintenance business unit. Each drainage district, other than Taramaire, has its own advisory committee of members elected to represent ratepayers specifically on drainage matters in their area. The Western Plains Drainage Committee also has responsibility for the management of the flood protection aspect of the activity. The drainage committees report directly to the Council, establishing levels of service with the Council and the community and recommending the annual or ongoing works programme. The Council then sets the rates to be collected on their behalf to fund these works. The Council currently owns and maintains: the land drainage schemes which have a replacement value of approximately $11million (excluding land value). Assets include 651 km of drains, 49km of stopbanks, 93 flood gates and control gates, and 4 pump stations the Flood Protection schemes which have a replacement value of $4.3million (excluding land value). Assets include 43km of stopbanks and 31 floodgates, and one pump station. Hauraki District Council also provides administrative support to the locally managed Taramaire Drainage District. Map of Hauraki Land Drainage Districts and Flood Protection area Taramaire Flood Protection Komata North Western Plains Opukeko Eastern Plains Tirohia Rotokohu The information contained in this document has been reproduced from a variety of sources. The varying data collection methods Approx. Scale 1:330,000 can lead to inconsistencies in the spatial relationship between the Hauraki District various datasets. The information is supplied in good faith. Land Drainage However, Council accepts no liability for any errors or omissions. Wednesday, 25 May 2011 It is the users responsibility to ensure that the data contained Districts herein is appropriate and applicable to the end use intended. Key legislative drivers and guidelines Land Drainage Act, 1908 Civil Defence and Emergency Management Act, 2002 Resource Management Act, 1991 Soil Conservation and Rivers Control Act, 1941 (and Amendment Act, 1946) Climate Change Response Act, 2002 Health Act, 1956 Governments Sustainable Development Action Plan Local Government Act, 2002 Local Government Act, 1974 Building Act, 2004 Heritage New Zealand Pouhere Taonga Act, 2014 Relevant Policies, Plans and Strategies Land Drainage Asset Management Plan Hauraki District Plan Hauraki District Council Consolidated Bylaw Asset Management Planning Policy Waikato Regional Council Regional Policy Statement and Regional Plan Hauraki District Council Engineering Manual Climate Change Policy Infrastructure Strategy Demand Management The Council’s drainage systems are nearly fully developed and are currently on a programme of maintenance and renewal. Capital works therefore focus mainly on programmed renewals. Development of land in the District for agricultural purposes has now been largely completed. As the Land Drainage activity essentially serves areas rather than population, very limited effect is expected on the future demand on the Council’s system of canals, drains, stopbanks and flood control structures as a result of population changes. It is likely that climate change will impact on the Land Drainage activity over time and may affect future extensions to and/or maintenance of this asset. The Council’s adopted assumption is that average annual rainfall is likely to slightly decrease over the next 100 years; however major rainfall events are predicted to intensify. Change is expected to be gradual and not to have a significant effect on the asset during the life of this Plan. As peat shrinks and the land contour changes, some re-orientation of the drainage network will be required. In addition a contribution to the capital cost of the pump project may be required. Increased drainage pumping capacity may be needed in time, to counteract the possible impact of climate change and rising sea level, in addition to that needed to provide for lower ground levels on the settling peat soils of the Hauraki Plains. While there is unlikely to be any major drainage development in the foreseeable future, small additions to the drainage network can be expected from time to time. The cost of these additions will be met by the beneficiaries of the additions. Provided that a number of conditions are met, the completed drain addition will be added to the network. The Council is aware that the predicted impacts of climate change could have significant effects on the foreshore and lower river stopbank requirements for the Regional Council’s river schemes. This may lead to the need for additional flood control measures and structures in the drainage districts. Given the relationship between the river schemes and the drainage districts, the Council will work closely with Waikato Regional Council to develop appropriate responses over the life of this Plan to mitigate the possible consequences of climate change. As well as addressing structural issues, funding issues will also need to be considered if additional works or assets are required. This could impact on the land drainage rates for users in the land drainage areas in the future. What are the significant negative effects on the local community? The cost of compliance with standards can impact the level of cost passed on to the ratepayers who receive the service. Intensive farming made possible by the land drainage activity leads to loss of natural wetland habitat thereby reducing biodiversity. Some

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