Introduction
Lakes, rivers, streams and wetlands (including their headwaters, margins and associated flood plains) and aquifers make up our freshwater systems. They are valued for their natural character, landscape, ecological and biodiversity values, amenity and recreational values, navigation and access, and stock, domestic and municipal water supply. Freshwater systems also provide an essential link between the land and the sea, including natural processes to regulate runoff during storms, receive and filter contaminants, and allow fish to reach spawning areas and upstream habitats.
Auckland is characterised by relatively small and shallow natural lakes, remnant numbers of wetlands, a few larger rivers and a network of small, shallow and short streams. Groundwater aquifers underlie both urban and rural areas and there are geothermal water resources in Auckland. The sources of municipal water supply for Auckland include a number of water supply lakes (created by dams), rivers and groundwater aquifers. Maintenance of the quality of freshwater and improved management of its quantity, allocation and use can improve the relationship between demand and supply of both surface and groundwater.
The loss of freshwater systems and degradation of their values, particularly small streams, is a significant issue facing Auckland. The piping and infilling of streams, including headwater reaches, has been prevalent in our past urban development and resulted in the permanent loss of important community and ecological resources and their values.
Sediment runoff from land development and the runoff of contaminants from urban land uses have contaminated urban streams, and led to undesirable impacts on coastal water quality and use and enjoyment of the CMA. Increased impervious surfaces in urban areas have also changed the amount and intensity of surface water runoff which can create or worsen flooding events, and the erosion of rivers and streams.
However, rivers and streams in particular also have an essential role as a natural component of an urban stormwater collection and management system. Development must therefore be managed to facilitate this function while retaining the natural, recreational and amenity values.
Past land development has had a significant impact on Auckland’s freshwater systems. It is now recognised that in many situations a water sensitive approach to development can provide for land development while retaining natural water systems and enhancing them where they are degraded. Intensification and redevelopment can also offer opportunities to restore and enhance degraded freshwater systems, and improve the natural environment in Auckland.
In rural areas lakes, rivers and particularly streams are physically affected by stock access to and trampling of stream beds, loss of riparian vegetation, and reduced water quality from the runoff of fertiliser, sediment and other contaminants from primary production activities. Major infrastructure in rural areas may also affect all types of freshwater resources.
In the Mana Whenua worldview, water represents the tears of Ranginui, the lifeblood of Papatūānuku, and is the domain of Tangaroa. The mauri of water is at the core of sustaining Papatūānuku. Mana Whenua are responsible for the kaitiakitanga of water, its spiritual essence to cleanse, and its importance to the ongoing well-being of people. Land-based activities can also compromise the ways in which Mana Whenua value water in rivers and streams. The mixing of different types of water through discharges, or by the diversion of these water bodies is contrary to Mana Whenua views on how water should be managed.
All of these matters need to be addressed in an integrated manner to minimise adverse effects on freshwater systems during subdivision, use and development. The National Policy Statement for Freshwater Management 2011 (NPSFM) and the New Zealand Coastal Policy Statement 2010 (NZCPS) provide both short-term and long-term directions that the Unitary Plan has to implement.
This needs to be done in a way that takes account of Auckland's physical, economic, social and cultural characteristics and requirements.
Explanation and reasons
These objectives and policies relate to the management of the quality and quantity of freshwater resources, both surface water and groundwater in Auckland. They are implemented through a variety of different plan provisions that deal with the management of land uses, the quality of both direct and indirect discharges, including sediment and organic and chemical contaminants, the taking, use and allocation of freshwater from streams and aquifers and disturbance of lake and river banks and beds. All of these activities affect the overall quality and availability of freshwater and the options for its human use and enjoyment, as well as the maintenance and protection of its biodiversity values.
Some freshwater bodies outside urban Auckland have high biodiversity and/or water quality and are included as management areas, with a protection oriented management approach. In urban areas particular attention is given to the management of stormwater quantity and quality from stormwater network systems and wastewater overflows from the public wastewater network. These discharges have the greatest adverse effects on the physical form and quality of urban streams, and are also a major source of degradation of coastal water quality and ecosystem values. Past experience has shown that the adverse effects of stormwater discharges cannot solely, or effectively, be managed “at the end of the pipe”. Stormwater management must also encompass the land use activities that contribute stormwater and associated contaminants to the stormwater network and integrated land and water management is an important focus of this approach.
Sediment being discharged from urban and rural streams is also a major source of freshwater and coastal contamination. The Auckland Plan sets a target of reducing the overall yield of suspended sediment to priority marine receiving environments by 15 percent between 2012 and 2040. This requires appropriate provisions to be put in place to ensure as far as practicable, soil and sediment are retained on the land and kept out of rivers, streams and coastal waters.
Surface water bodies and groundwater aquifers cannot supply all of Auckland's future water needs, without more efficient management approaches to the allocation and use of available freshwater being introduced. The principal consumptive use of freshwater in Auckland is for municipal water supply, which is in part supplied from the Waikato River. Maintaining the quality of freshwater so it is fit for purpose, and managing the allocation and use of water according to priority users and making more efficient use of available supply are key policy approaches taken in the Unitary Plan.