Nitrogen is an essential nutrient for plants. Small amounts are a natural component of healthy rivers, but agricultural and urban land use can add more nitrogen to waterways.

Phosphorus is an essential nutrient for plants, and small amounts are a natural component of healthy rivers. Agricultural and urban land use can add more phosphorus to waterways, which can cause excessive growth of algae and degrade river habitats.

Escherichia coli (E.coli) is a group of bacteria commonly found in the intestines of warm-blooded animals, including people. E.coli in fresh water can indicate the presence of pathogens (disease-causing organisms) from animal or human faeces.

Water clarity is a measure of underwater visibility in rivers and streams. Fine particles like silt, mud, and organic material can reduce the clarity of water.

Benthic macroinvertebrates are small animals without backbones (eg insects and worms). They live on and under submerged logs, rocks, and aquatic plants on the beds of rivers and streams during some part of their life cycle.

Urban streams have unique water quality issues due to the presence of infrastructure and stormwater runoff from high levels of impervious surfaces. 

Nitrogen occurs naturally in groundwater, but usually at very low concentrations. Agricultural and urban land use can add more nitrate-nitrogen to groundwater.

Pesticides are commonly used in New Zealand to control insects, diseases, and weeds in primary industries. They can harm the environment and human health. 

When nutrients accumulate in lakes (referred to as ‘nutrient enrichment’) above certain levels, they can make the lakes murky and green with algae. The lake trophic level index (TLI) indicates the health of a lake based on its degree of nutrient enrichment.

Nitrogen is an essential nutrient for plant growth. It occurs naturally in the environment but is added in agricultural processes (typically as fertiliser) to boost production.

Nitrogen is an essential nutrient for plant growth. It occurs naturally, but in agricultural systems more nitrogen is commonly added to soils as fertiliser or from livestock waste.

River flow is the quantity of water passing a point over a certain time. Each river or stream has its own natural flow characteristics, such as peak flows following rain or high spring flows from snow melt.

Each river has natural patterns of high and low flows that influence how much water is available for irrigation, drinking water, hydroelectricity generation, and recreational activities. 

As the main source of renewable energy in New Zealand, the use of water supports the production of the electricity industry.

Fine sediment is the collective term for inorganic particles smaller than 2mm that are deposited on the beds of rivers and streams.

Groundwater is the water stored beneath Earth’s surface in aquifers (layers of water-bearing rock or sand). It is used for human and stock drinking water, irrigation, and industry.

Aquifers store water that can feed lakes and rivers. They are also an important source of water for towns, cities, farms, and industries.

Wetlands support unique biodiversity and provide important services. They clean water of excess nutrients and sediment, help absorb floodwaters, and act as carbon sinks (remove carbon dioxide from the atmosphere).

The lake submerged plant index (LakeSPI) measures the ecological condition of lakes. Ecological condition is informed by the diversity and extent of native and invasive plant species. 

Kaitiakitanga is the active custodianship role tangata whenua have for their freshwater environments. 

The cultural health index (CHI) is a national tool that measures factors of cultural importance to Māori in the freshwater environment. 

Historically, kōura (freshwater crayfish) was an important food for Māori, who harvested large numbers for consumption and trading. 

The conservation status of a species represents their risk of extinction. New Zealand has a diverse range of native freshwater fish and invertebrates, many of which are endemic (found nowhere else in the world) and have localised distributions.

 Freshwater fish are an important component of freshwater ecosystems and have high cultural, commercial, recreational, and intrinsic biodiversity value.

Freshwater plant and animal pests can reduce the indigenous biodiversity through predation, competition for food and habitat, and by damaging aquatic habitats.

Human-made structures such as culverts, weirs, stormwater pump stations, tide gates, and dams can obstruct diadromous fish migrations and prevent fish from reaching critical habitats. 

Fresh water in New Zealand is highly valued for recreational activities, including fishing. Freshwater angling is a popular leisure activity.

Includes indicators for livestock numbers, land use, land cover, soil erosion, water physical stocks and rainfall.