Given the scale and spatial distribution of recent development (together with further development in the future) there is the potential for significant cumulative effects on the natural environment.
The scattered nature of recent development, including ribbon development along the coast and along transport corridors, sporadic development on the urban fringes, and scattered rural residential development throughout the rural and coastal areas poses challenges when managing environmental effects, particularly cumulative effects over the long term. Some of these effects are described below.
Outstanding natural features and landscapes
Around 20% of the district is designated as either outstanding or notable landscape in the District Plan. These landscapes are regionally and, in some instances, nationally significant. These are our iconic landscapes that distinguish the district and make it unique.
Approximately 10% of lots subdivided over the last 10 years have been in either outstanding or notable landscape areas and there will be on-going demand for residential development in these areas. Growth must be managed to ensure that these special and often vulnerable landscapes are protected from over-development.
The alternative is that over time the cumulative effects of development will overwhelm these landscapes and the very values that made them significant will be lost. The District’s unique identity as a consequence diminishes and those traits that made the district special are lost forever.
Natural character of the coast
The Whangarei District coastline is one of the most beautiful in the world. For this reason demand for residences and holiday homes along the coast is high. This demand will continue.
Around 10% of the district is in the coastal area yet approximately 30% of the lots subdivided over the last 10 years have been in the coastal area. There are very real dangers of development along the coast adversely affecting the natural character of the coast.
Ribbon development and sporadic development can result in over development that diminishes the very values that attracted people to the coast. Adverse effects can accumulate over time so that eventually the natural character is all but lost forever. Growth along the coast must be managed to prevent this.
The Whangarei District has a unique biodiversity, yet much of it is threatened. For example, there are 201 threatened species within the district. Of these, 120 are threatened animals, and 81 are threatened plants. In addition, 12% of the district’s land area is classified as acutely threatened environment, and 13% is chronically threatened environment.
Less than 5% of the wetlands remain as a result of drainage and disturbance. Some wetland types are now close to being lost forever. Remaining wetlands are under pressure from drainage, invasion by pest plants, reclamation for urban development, grazing and trampling of littoral vegetation by stock.
Over the last 10 years 62% of lots subdivided have been in acutely or chronically threatened land environments. In addition, 20% of the lots subdivided over the last 10 years have intersected a Protected Natural Area of ecological significance.
The scattered nature of recent development has caused widespread impacts on natural habitat and biodiversity. These impacts are difficult to manage across such a dispersed area. If the loss of indigenous biodiversity and the destruction of natural habitats of indigenous flora and fauna is to be halted, a much more proactive response is necessary. Development must take account of, and protect and/or enhance biodiversity and natural habitat.
High class soils
The Whangarei District possesses some highly fertile and versatile soils. These are often of volcanic origin. There are approximately 12,000 hectares of high class versatile soils within the Whangarei District. Yet these same soils are often highly desirable for residential or rural residential development.
Over the last five years around 15% of these prime soils have been subdivided. The average lot size is 2.2 hectares, effectively removing them from productive use in the future. In addition, 14% of the lots subdivided over the last 10 years were located on high class soils.
With widespread rural residential development occurring throughout the rural area these soils are being removed from productive use. Given that only 3% of the total land area of New Zealand is comprised of high class soils (those with few impediments to intensive arable use) subdividing these soils for residential or rural residential development is not a sustainable use of a highly valuable and limited natural resource.
Rural amenity/reverse sensitivity
Another consequence of widely dispersed rural residential development is the effect on rural amenity and reverse sensitivity.
Scattered residential development in the rural area often results in adverse effects on rural amenity in the sense of changing the usual characteristics of a rural landscape. An open vista becomes built-up, there are increased traffic movements, increased noise, and often an increased demand for improved infrastructure (roading, sewerage, water, etc.).
At the same time, reverse sensitivity becomes an issue. People attracted to the rural environment often complain about farming activities taking place alongside them. Noise, spray drift, animal movements, etc. become cause for complaint. Productive use of the land is further diminished.
Growth must be managed to avoid adverse effects on rural amenity and reverse sensitivity issues if it is to be sustainable.
Overall, the air quality in the Whangarei district is good. Some parts of Whangarei City have poor air quality on occasions during winter months. In winter there are periods of cold, calm weather when pollutants can build up to levels which may affect human health.
In Whangarei City domestic fires contribute up to 50% of air pollution in urban areas and up to 70% in residential areas. Transport emissions contribute up to 50% of particulates in urban areas and up to 20% in residential areas.
Marsden Point Refinery has consent to discharge pollutants to air, including sulphur dioxide. Peak concentrations at the three monitoring sites remain below the NZ ambient air quality guideline.
Water quality has been affected by development in the Whangarei district both along the coast and inland waterways.
Ribbon and sporadic development along the coast, particularly in unserviced areas, has the potential to adversely affect coastal water quality.
Harbours and estuaries are especially vulnerable to stormwater runoff and seepage from septic tanks.
Sediment input from erosion caused by forestry, farming and other earthworks can also have significant impact in some areas.
Sewage spills in Whangarei Harbour are causing concern for residents and marine farmers. After heavy rain, water quality is often not suitable for shellfish gathering or swimming due to bacterial levels. Water quality is poor in the upper harbour near the Town Basin. The upper harbour sampling sites exceed the 130 enterococci per 100ml guideline on between 20-35% of sampling occasions.
Water quality in inland waterways is affected by farming activities in the rural areas and stormwater discharge in urban areas. Both contribute to a deteriorating quality of water in streams and rivers. Some streams and rivers are unsafe for swimming.
Few freshwater lakes remain within the district. Three lakes receive some form of monitoring within Whangarei District; Lake Waro is oligotrophic and in moderate-high condition, Ruakaka is hypertrophic and the condition is unknown, and Lake Ora is of low condition.
Risks from natural hazards including land instability, flooding, coastal hazards, volcanism, earthquakes and climate change pose challenges to development.
Flooding and other weather-related hazards (landslips) are the most common natural hazards in the district followed by coastal erosion and inundation. Land instability is a threat in parts of the district.
Development must take into account the risks presented by natural hazards. The scattered nature of recent land development makes avoiding or mitigating risks from natural hazards difficult.
Over the last 10 years 24% of the lots subdivided throughout the district have been in flood susceptible areas. In addition 0.5% of the lots subdivided over the last 10 years have occurred within a coastal hazard zone.
Development, to be sustainable over the long term, particularly given the potential for climate change, must avoid or mitigate the risks presented by natural hazards.
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Social and Cultural Wellbeing