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Glossary

NPS-FM
The National Policy Statement for Freshwater Management (NPS-FM) provides direction about how local authorities should carry out their responsibilities under the Resource Management Act 1991 for managing fresh water. It’s particularly important for regional councils, as it directs them to consider specific matters and to meet certain requirements when they are developing regional plans for fresh water. The NPS-FM came into effect on 1 August 2014.
Visual clarity
Water clarity and underwater visibility is important for recreation such as swimming. It is also important from an aesthetic point of view – most people prefer to see clear water in our rivers and streams.
Turbidity
A measure of the murkiness of water, reflecting the amount of suspended sediment in the water. High turbidity reduces the amount of light available to the plants and animals living in the water. It reduces the ability of plants to photosynthesise. It also makes it difficult for fish and other animals to see their prey. Turbidity should be less than 5 NTU (turbidity measurement scale) for water to support plant growth.
Phosphorus
Phosphorus is a nutrient that can encourage the growth of nuisance aquatic plants. These plants can choke up waterways and out-compete native species. High levels of phosphorus in water can be a result of runoff from agricultural land. Ideally, total phosphorus levels in water should be less than 0.04 grams per cubic metre to prevent excessive growth of nuisance plants.
pH
A measure of the acidity or alkalinity of water. A very high or very low pH means that water can be unsuitable for aquatic life. The pH range that is suitable for aquatic plants and animals is 6.5 to 9.
Periphyton
A complex mixture of algae, cyanobacteria, microbes and detritus that’s attached to submerged surfaces (such as rocks) in most aquatic ecosystems. Periphyton plays an important role by being a food source for invertebrates and some fish. However, too much periphyton can smother the benthic environment, making it unsuitable as a habitat for many macroinvertebrates.
Nitrogen
Nitrogen is a nutrient that can encourage the growth of nuisance aquatic plants. These plants can choke up waterways and out-compete native species. High levels of nitrogen in water can be a result of runoff and leaching from agricultural land. Ideally, total nitrogen levels in water should be less than 0.5 grams per cubic metre to prevent excessive growth of nuisance plants.
Macroinvertebrates
An invertebrate that is large enough to be seen with the naked eye (without a microscope). For example, insect larvae, worms, snails.
Limits
The NPS-FM defines a limit as “the maximum amount of resource use available, which allows a freshwater objective to be met”. For example, limits on the total amount of water that can be taken out of a freshwater body, or the amount of contaminants that can be discharged into it without compromising the desired outcomes.
Invertebrate
An animal without a backbone (vertebrae). For example, insects and crustaceans, such as crabs.
Indigenous vegetation
Vegetation that is naturally found in an area (without human aid or being spread there by people).
Freshwater objectives
The intended environmental outcomes for a water body that will provide for the values the community considers important.
E. coli (Escherichia coli)
A type of bacteria commonly found in the intestines of warm-blooded animals, such as birds and mammals (including people, cows and sheep). High concentrations of this bacteria exceeding water quality guidelines indicate faecal contamination, which can be harmful to people and stock.
Ecosystem
A community of living organisms (plants, animals and micro-organisms), and the non-living components of their environment (things like air, water and mineral soil), which interact together as a system.
Dissolved oxygen
The concentration of oxygen dissolved in water, expressed in mg/l or as per cent saturation. (Saturation is the maximum amount of oxygen that can theoretically be dissolved in water at a given altitude and temperature.)
Benthic
an organism (plant or animal) that lives on the bottom sediments (e.g. mud, sand or gravel) of a water body such as a river, lake or estuary.
Biodiversity
Short for biological diversity – the variety of life on Earth. At a local level it includes the variation of life in an ecosystem, including all the plants, animals and micro-organisms.