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    There are several physical, chemical and biological indicators that are monitored for water quality purposes.

    Discover some of the physical, chemical and biological factors that are used as indicators of water quality. Select a label to watch videos of Waikato Regional Council water scientist Dr Eloise Ryan speak about the indicators. The labels also have links to related Hub resources.

    To use this interactive, move your mouse or finger over any of the labelled boxes and click to obtain more information.

    Use the interactive Stream health monitoring and assessment to learn how to conduct water quality tests associated with these indicators.

    Background image of scientists in stream by Juliet Milne, NIWA, CC BY-NC-ND 4.0

    Transcript

    The purpose of monitoring

    National, regional and local agencies regularly monitor the country’s waterways. They use physical, chemical and biological indicators as evidence of water quality.

    Dr Eloise Ryan explains why Waikato Regional Council monitors water. The following resources explore water quality and how and why we monitor it.

    Articles

    Videos

    Select here to view the video transcript and copyright information.

    Acknowledgement: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council

    Vegetation

    Vegetation growing in the water and on the banks of a waterway forms an important part of the habitat. Bank vegetation provides shade to cool the water and a habitat for insect life. It stabilises the banks and helps to filter nutrient and sediment run-off. Aquatic vegetation is a habitat for invertebrates and fish living in the water. Land use and introduced species can have negative impacts on vegetation.

    Dr Eloise Ryan tells us about the importance of land cover and the impacts of land use.

    The following resources explore the importance of riparian vegetation on water quality and freshwater aquatic habitats.

    Articles

    Select here to view the video transcript and copyright information.

    Acknowledgement: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council

    Nutrients

    A nutrient is a chemical that organisms need to live and grow. Nutrients such as nitrogen and phosphorus are naturally occurring, but urban and rural land use practices can add more of these nutrients to waterways. Excess nutrients lead to unwanted plant growth, which affects habitat and recreational uses.

    Dr Eloise Ryan explains why Waikato Regional Council assesses total nitrogen and total phosphorus as water quality indicators.

    The following resources provide information on how nutrients enter waterways, the impacts they can have and ways of managing or preventing them from entering.

    Articles

    Videos

    Activities

    Select here to view the video transcript and copyright information.

    Acknowledgement: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council

    pH

    In chemistry, pH is a number that expresses the acidity or alkalinity of a solution. A neutral solution has a pH of 7. Acidic solutions are those with a pH less than 7, and basic solutions are those with a pH greater than 7.

    pH affects drinking water supplies. Water with low pH can corrode or dissolve metals such as pipes. Water with high pH may taste bitter, leave mineral deposits in pipes and appliances and require additional chlorine to disinfect for drinking water.

    In aquatic ecosystems, changes in pH levels can stress organisms and reduce hatching and survival rates. Changes in pH can also increase the solubility of nutrients like phosphorus and make them more accessible for plant growth, which may lead to algal blooms.

    Contaminants from spills and from land use can affect the pH of water.

    Dr Eloise Ryan discusses pH as an indicator of water quality.

    Select here to view the video transcript and copyright information.

    Acknowledgement: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council

    Pest animals

    Aquatic ecosystems also have introduced pests. Pest animals like rabbits and possums can destroy riparian plants. Aquatic animals such as koi carp and catfish foul the water and compete with native species for food and habitat.

    Dr Eloise Ryan talks about pest animals in the Waikato River system.

    The following resources explore the impacts of pest animals on terrestrial and aquatic habitats.

    Articles

    Interactives

    Activities

    PLD webinar

    Select here to view the video transcript and copyright information.

    Acknowledgement: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council

    Water clarity

    Water clarity or turbidity refers to how clear or cloudy the water is. Clarity is important for fish to find their prey, for plants to photosynthesise and for people to be able to swim safely.

    Clarity is affected by things like sediment and algae. Sediments can be soil or other small pieces of organic and geological materials. Sediments are naturally part of water bodies, but land use and weather-related events can increase the amount of sediment in the water. In the Waikato region, pest fish like koi carp stir up the sediment, reducing water clarity.

    Dr Eloise Ryan talks about water clarity and sediment.

    The following resources explore some of the factors that lead to reduced water clarity and ways in which we can help to prevent water from becoming turbid.

    Articles

    Interactives

    Videos

    The following videos provide information about the impacts of sediment on water quality. Although some of the videos refer to marine ecosystems, the impacts are similar for freshwater ecosystems.

    Select here to view the video transcript and copyright information.

    Acknowledgement: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council

    Weather

    Weather events impact water quality. Heavy rains can cause erosion, introducing sediment into waterways. The sediment makes the water turbid and may also carry nutrients or contaminants into the water.

    An example of a weather-related event is evident in this image of the confluence of the Waipā River and Waikato River after heavy rain.

    Lack of rain can lower water levels, which may affect water flow and water temperature.

    Weather is different from climate. Climate refers to weather conditions averaged over 30 years or more. In New Zealand, our climate indicates that winters tend to be wetter and cooler than summers. These conditions affect water temperature and pest plant growth (algal blooms). Global climate change may lead to warmer water temperatures.

    Acknowledgement: John Greenwood, J Greenwood Photography

    Water flow

    Water flow is naturally influenced by the catchment and the shape of the river. Humans can alter water flow by straightening channels, building dams and taking water from rivers for irrigation or other uses.

    Dr Eloise Ryan explains the effect of water flow on native species.

    The following resources explore river catchments, native fish habitats and water flow and human influences on water flow.

    Articles

    Interactives

    Select here to view the video transcript and copyright information.

    Acknowledgement: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council

    Pest plants

    Pest plants invade aquatic ecosystems and compete with native plants for the same resources. Pest plants can range in size from microscopic algae to large willow trees.

    Algae naturally occur in our lakes and rivers. They become a pest when nutrients from urban wastewater, fertilisers or animal wastes enter the waterways and stimulate excess growth – algal blooms.

    Dr Eloise Ryan talks about ‘good’ and ‘bad’ aquatic plants.

    The following resources provide information about pest plants:

    Articles

    Select here to view the video transcript and copyright information.

    Acknowledgement: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council

    Geology

    Geology determines what makes up the bottom (substrate) of a waterway. Hard bottoms are made up of rocks or gravels, whereas soft-bottomed waterways tend to be muddy or weedy. The type of catchment can influence the substrate. Streams in upper catchments tend to have rockier bottoms than slower-flowing streams in lower catchments.

    Freshwater macroinvertebrates and native fish may have physical adaptations that suit a particular habitat and substrate. If the waterway is altered by the addition of extra sediment, this impacts water clarity and plant and animal life.

    Dr Eloise Ryan explains the role of geology and its impacts on water quality.

    The following resources provide information about catchments, substrates and habitat.

    Articles

    Interactives

    Select here to view the video transcript and copyright information.

    Acknowledgement: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council

    Acknowledgement

    This interactive has been developed in partnership with the Waikato Regional Council as part of the Rivers and Us resource.

    Rights: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council Published 16 March 2020 Size: 660 KB Referencing Hub media