Council has four main State of the Environment monitoring programmes in the coast:
- Coastal sediment quality
- Harbour water quality
- Estuary Monitoring
Council monitors all activities authorised by resource consents in the coastal marine environment including:
- Coastal structures such as sea walls, jetties and boat ramps
- Industrial and stormwater discharges
If you’re doing construction in the coastal marine area, read our Guidelines for construction work in the coastal marine area. You'll find information that will help you comply with any resource consent to work within Northland's coastline and protect our environment.
Council investigates environmental incidents including unauthorised coastal structures and discharges.
If you would like to report an environmental incident please contact Councils 24 hour environmental hotline on 0800 504 639 or email email@example.com
Each summer, we test the water quality at a number of Northland's popular coastal and freshwater swimming spots to check its suitability for swimming.
Testing starts in late November each year and continues through to March the following year.
Northland Regional Council monitors sediment metal and nutrient concentrations in surficial sediments at 32 sites in the Whāngārei Harbour and Bay of Islands. Council monitors these sites every two years.
The main objectives of this programme are to assess the contaminant and nutrient enrichment status of the sediment, identify environmental issues and track changes in the quality of the sediment over time. This information can then be used to assess the effectiveness of Regional Plans and to help inform policy initiatives and strategies.
Heavy metals can have lethal and sub lethal effects on marine plants and animals and in a contaminated environment the species diversity and species richness may decrease as the community becomes dominated by a smaller number of more tolerant species, which are able to survive and reproduce in these conditions. Metal contaminants are typically not subject to bacterial attack or other breakdown so they are permanent additions to the marine environment. Although plants and animals can usually regulate metal contaminant within a certain range, metals that cannot be excreted remain within the organisms and accumulate over time and can interfere with biological processes. The contaminants can also move progressively up the food chain as organisms are consumed and this may ultimately pose a risk to human health.
While nutrients are essential for all forms of life, nutrients that enter the environment from anthropogenic sources, such as fertilizer, storm water and treated wastewater may exceed the needs of an ecosystem. Initially surplus nutrients may stimulate algal growth and subsequently benthic communities and fish populations because there is an increase in food via additional plant material and organic detritus. However, large increases in algae can disturb the ecosystem, as algal growth can decrease light levels, and as the algae dies they are decomposed by bacteria which consume oxygen and can cause the water to become anoxic (hypoxia). Nutrient enrichment can also cause algal blooms including toxic algal blooms.
Northland Regional Council monitors water quality at 41 sites in the Whāngārei Harbour, Bay of Islands and Kaipara Harbour. The objectives of these programmes are to assess the water quality of the harbours, identify environmental issues and to track changes in the quality of water over time. We currently monitor 12 chemical and physical water quality parameters, including micro-bacteria, nutrients and water clarity.
Micro-bacteria such as enterococci and faecal coliforms are indicators of faecal contamination. Concentrations of micro bacteria can therefore help us to understand if water is safe for contact recreation. Sources of micro-bacteria include discharges or overflows from municipal waste water treatment plants, leakage from septic systems, runoff from agricultural land and farm dairy effluent discharges. In some locations birds and wildfowl can also cause high levels of micro-bacteria.
While nutrients are essential for all forms of life, nutrients that enter the environment from human activities and sources, such as fertilizer, storm water runoff and treated wastewater discharges may exceed the needs of an ecosystem. Too much nutrients can cause excessive plant growth leading to algal blooms and lowered levels of dissolved oxygen. This can reduce the life-supporting capacity of the ecosystem, as well as posing a human health risk both through contact with toxic algal blooms and the health effects of eating contaminated shellfish.
Water clarity is important for healthy marine ecosystems. Poor water clarity also reduces social, cultural and aesthetic values. Water clarity can be reduced by the growth of phytoplankton and human activities that increase levels of suspended solids entering the coastal environment. High levels of material in the water column can restrict light transmission which affects the amount of photosynthesis (primary production) by aquatic plants and consequently other species that are dependent on them such as fish and shellfish. Seaweeds and seagrass typically require more light for photosynthesis than phytoplankton and are particularly susceptible to reduced light levels of suspended sediments because they are attached to the seabed. Suspended sediments can also clog fish gills and reduce the ability of fish to see prey and detect predators. High levels of suspended solids may also protect micro-bacteria from ultraviolet light.
Northland Regional Council has established an estuary monitoring programme to assess the ecological health at 13 sentinel sites in Whāngārei Harbour, Kerikeri Inlet, Ruakaka Estuary, Whangaroa Harbour and the Arapaoa River in the Kaipara Harbour. The monitoring programme was implemented to assess the health of representative intertidal sites and provide baseline data, which can be used to track changes in the health of these sites over time. The programme involves sampling ecological communities, nutrient and metal concentrations, and the physical properties of the sediment. This enables us to relate patterns in the ecological communities to the sediment properties.
A key component of this programme involves sampling the marine invertebrates that live on intertidal sand and mud flats. The abundance, diversity and the species composition of the communities can be used as indicators of environmental health and changes to environmental conditions.
Marine invertebrates found in our estuaries include well known species such as cockles, pipis, crabs and whelks but also smaller less familiar animals including marine worms. These animals are important food sources for larger animals including, fish, such as snapper, birds and humans.
These animals also play important roles in the functioning of coastal ecosystems. For example suspension feeding invertebrates can improve water clarity as these animals filter suspended particles from the water column, while marine worms that build burrows can help to oxygenate the sediment.
Marine invertebrates are useful environmental indicators because they are usually relatively immobile so unlike larger animals like fish they can't swim away or avoid a disturbance. The animals present at particular site have therefore integrated the environmental conditions at a particular site over a period of time. There is a wide range of different species that differ in their responses to different environmental conditions.
The ecological communities can change in response to changes in environmental conditions including nutrient enrichment, metal contamination and changes to the physical composition of the sediment.
While nutrients are essential for all forms of life, nutrients that enter the environment from anthropogenic sources, such as fertilizer, storm water and treated wastewater may exceed the needs of an ecosystem. Initially surplus nutrients may stimulate benthic communities because there is an increase in food via additional plant material and organic detritus. However, as sediment organic matter increases the oxygenated portion of the sediment can become limited to the surface of the sediment or may be eliminated altogether, and dissolved oxygen concentrations can drop to levels that are lethal for some organisms. Under these conditions, animals may die or migrate from the affected area and the community may become less diverse as it is recolonised by a smaller number of opportunist species that are tolerant of low oxygen conditions.
Heavy metals can have lethal and sub lethal effects on marine plants and animals and in a contaminated environment the species diversity and species richness may decrease as the community becomes dominated by a smaller number of more tolerant species, which are able to survive and reproduce in these conditions. Metal contaminants are not subject to bacterial attack or other breakdown so are permanent additions to the marine environment. Although plants and animals can usually regulate metal contaminant within a certain range, metals that cannot be excreted remain within the organisms and accumulate over time and can interfere with biological processes. The contaminants can also move progressively up the food chain as organisms are consumed and this may ultimately pose a risk to human health.
Physical sediment properties
The physical properties of the sediment can also influence biological community. Some animals like cockles and pipis prefer to live in sandy sediments, while other animals such as marine worms can live in mud dominated habitats.
The erosion of soil and its transport as sediment through rivers and streams to the coastal environment is a natural process. However, the rate at which sedimentation is now occurring has been accelerated by land clearance for agriculture, forestry and urban development. Increased sediment inputs into our coastal environment can have a number of adverse impacts on both human and ecological values. Sediment can reduce light levels in the water which affects plant growth, and the ability of animals to find prey and avoid predators. It can also smother marine plants and animals and cause a shift from sandy environments to shallow turbid muddy environments.
Northland Regional Council has investigated sediment accumulation rates and sources of sediment in Whāngārei Harbour, Bay of Islands and Kaipara Harbour. These investigations have estimated sediment accumulations rates in the Kaipara Harbour, Bay of Islands and Whāngārei Harbour of between 2.4 mm per year and 6.4 mm per year, over the last 100 years. This compares with an average sediment accumulation rate of 0.23 mm per year during the last 10,000 years prior to deforestation by humans.
This order of magnitude increase in sedimentation is consistent with increased soil erosion following large-scale deforestation and indicates a major shift in the sedimentary regime of Northland estuaries.
The information from these studies will be used by NRC to make informed decisions on activities that contribute to sediment erosion and prioritise land management initiatives to reduce erosion and sediment runoff into Northland's coastal environment.
For more information download our latest technical report or view the latest results in our resource library
Gravity corer collecting sediment cores, which are used to determine sediment accumulation rates.