Our land use and freshwater

Our land use affects the quality of our freshwater and the species living in it.

Effects of taking water

As urban areas in Aotearoa New Zealand expand and agriculture becomes more intensive a larger volume of water is taken out of rivers, lakes, and groundwater.

Taking water from rivers alters the volume and flow of water. This can degrade freshwater ecosystems and reduce freshwater quality.

Find out more in Our land 2021 report

Effects of irrigation

Five per cent of agricultural land is irrigated. The amount of irrigated land is increasing especially land irrigated for dairy farming.

Irrigation uses large amounts of water. Scientific models predicted that irrigation had the greatest potential to reduce river flows across the country compared to other water uses.

Find out more in Our land 2021 report

New Zealand irrigated land area

nz irrigated land area
New Zealand irrigated land area between 1970 and 2020. From 2000 to 2020, the size of irrigated land area increased by almost 400 hectares.

Nitrogen, phosphorus, and sediment in freshwater

Excess sediment and pollutants can cause poor ecological health and reduce biodiversity in rivers and lakes near urban, farmed and forestry lands.                               

Applying nitrogen or phosphorus fertilisers to the soil continuously can increase the risk of these elements moving into freshwater and leaching into groundwater.                                                       

Nitrogen and phosphorus can cause algal blooms in rivers and lakes. This reduces the amount of oxygen in the water for plants and for fish to breathe. Too much nitrate-nitrogen (one form of nitrogen) in groundwater used for drinking water is also a potential human health concern.                                                           

Fencing streams and timing irrigation are some ways to reduce the amount of nitrogen that ends up in our freshwater.

Find out more in Our land 2021 report

Urban and agricultural waste

Urban and agricultural land-uses produce waste which can also pollute waterways.

This can happen when rural waste (eg, agricultural plastics, and agrochemicals and their containers) blows into waterways or when contaminants soak into groundwater.

Pollutants from cities and towns (eg, heavy metals from vehicles, plastic litter and garden fertilisers) can enter rivers, lakes, estuaries, and beaches through stormwater networks.

Find out more in Our land 2021 report

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