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Advances in the aquatic sciences
RESEARCH ARTICLE (Open Access)

Attribution of river water-quality trends to agricultural land use and climate variability in New Zealand

T. H. Snelder https://orcid.org/0000-0002-2330-4563 A E , C. Fraser https://orcid.org/0000-0002-4349-8174 A , S. T. Larned https://orcid.org/0000-0003-4635-750X B , R. Monaghan https://orcid.org/0000-0001-9469-2770 C , S. De Malmanche D and A. L. Whitehead https://orcid.org/0000-0002-4164-9047 B
+ Author Affiliations
- Author Affiliations

A LWP Ltd, Christchurch, New Zealand.

B National Institute of Water and Atmospheric Research, Christchurch, New Zealand.

C AgResearch, Mosgiel, New Zealand.

D Ministry for the Environment, Wellington, New Zealand.

E Corresponding author. Email: ton@lwp.nz

Marine and Freshwater Research 73(1) 1-19 https://doi.org/10.1071/MF21086
Submitted: 21 March 2021  Accepted: 25 August 2021   Published: 30 September 2021

Journal Compilation © CSIRO 2022 Open Access CC BY-NC-ND

Abstract

Trends at 1051 river monitoring sites across New Zealand incrementing annually for time windows of 10 and 20 years over the 28-year period ending 2017 were assessed from regular observations of six water quality variables. Between-site variation in trend strength and direction was modelled as a function of an indicator based on the Southern Oscillation Index (SOI) and the mean of and changes to catchment: (1) stocking intensity associated with pastoral livestock; and (2) area associated with plantation forest. The SOI indicator made consistent contributions to the models for the 10-year windows, but the land use indicators did not, indicating that land use signals were generally swamped by the effects of climate variability at this timescale. Some land use indicators made consistent and certain contributions to the models for the 20-year time windows. Depending on the water quality variable, some land use indicators were associated with both water quality improvement and degradation. The relationships were generally consistent with plausible explanations including changes in land use, land use intensity and land management practices. Robust attribution of water quality changes to changes to specific agricultural land uses will enable the development of precise and effective policies to achieve water quality improvement.

Keywords: climate, land use, New Zealand, rivers, trends, water quality.


References

Ballantine, D. J., and Davies-Colley, R. J. (2014). Water quality trends in New Zealand rivers: 1989–2009. Environmental Monitoring and Assessment 186, 1939–1950.
Water quality trends in New Zealand rivers: 1989–2009.Crossref | GoogleScholarGoogle Scholar | 24197562PubMed |

Bäumler, R., and Zech, W. (1999). Effects of forest thinning on the streamwater chemistry of two forest watersheds in the Bavarian Alps. Forest Ecology and Management 116, 119–128.
Effects of forest thinning on the streamwater chemistry of two forest watersheds in the Bavarian Alps.Crossref | GoogleScholarGoogle Scholar |

Behmel, S., Damour, M., Ludwig, R., and Rodriguez, M. J. (2016). Water quality monitoring strategies – a review and future perspectives. The Science of the Total Environment 571, 1312–1329.
Water quality monitoring strategies – a review and future perspectives.Crossref | GoogleScholarGoogle Scholar | 27396312PubMed |

Benjamini, Y., and Hochberg, Y. (1995). Controlling the false discovery rate: a practical and powerful approach to multiple testing. Journal of the Royal Statistical Society – B. Methodological 57, 289–300.
Controlling the false discovery rate: a practical and powerful approach to multiple testing.Crossref | GoogleScholarGoogle Scholar |

Bewsell, D., Monaghan, R. M., and Kaine, G. (2007). Adoption of stream fencing among dairy farmers in four New Zealand catchments. Environmental Management 40, 201–209.
Adoption of stream fencing among dairy farmers in four New Zealand catchments.Crossref | GoogleScholarGoogle Scholar | 17562101PubMed |

Bouraoui, F., and Grizzetti, B. (2011). Long term change of nutrient concentrations of rivers discharging in European seas. The Science of the Total Environment 409, 4899–4916.
Long term change of nutrient concentrations of rivers discharging in European seas.Crossref | GoogleScholarGoogle Scholar | 21911245PubMed |

Brooks, B. (1916). Erosion of watersheds and its prevention. Journal – American Water Works Association 3, 409–414.
Erosion of watersheds and its prevention.Crossref | GoogleScholarGoogle Scholar |

Chanat, J. G., and Yang, G. (2018). Exploring drivers of regional water-quality change using differential spatially referenced regression – a pilot study in the Chesapeake Bay watershed. Water Resources Research 54, 8120–8145.
Exploring drivers of regional water-quality change using differential spatially referenced regression – a pilot study in the Chesapeake Bay watershed.Crossref | GoogleScholarGoogle Scholar |

Chiew, F. H. S., and McMahon, T. A. (2002). Global ENSO-streamflow teleconnection, streamflow forecasting and interannual variability. Hydrological Sciences Journal 47, 505–522.
Global ENSO-streamflow teleconnection, streamflow forecasting and interannual variability.Crossref | GoogleScholarGoogle Scholar |

Choquette, A. F., Hirsch, R. M., Murphy, J. C., Johnson, L. T., and Confesor, R. B. (2019). Tracking changes in nutrient delivery to western Lake Erie: approaches to compensate for variability and trends in streamflow. Journal of Great Lakes Research 45, 21–39.
Tracking changes in nutrient delivery to western Lake Erie: approaches to compensate for variability and trends in streamflow.Crossref | GoogleScholarGoogle Scholar |

Davies-Colley, J. R. (2013). River water quality in New Zealand: an introduction and overview. In ‘Ecosystem Services in New Zealand: Conditions and Trends’. pp. 432–447. (Manaaki Whenua Press: Lincoln, New Zealand.)

Davies-Colley, R. J., Smith, D. G., Ward, R. C., Bryers, G. G., McBride, G. B., Quinn, J. M., and Scarsbrook, M. R. (2011). Twenty years of New Zealand’s national rivers water quality network: benefits of careful design and consistent operation. Journal of the American Water Resources Association 47, 750–771.
Twenty years of New Zealand’s national rivers water quality network: benefits of careful design and consistent operation.Crossref | GoogleScholarGoogle Scholar |

Di, H. J., and Cameron, K. C. (2002). Nitrate leaching in temperate agroecosystems: sources, factors and mitigating strategies. Nutrient Cycling in Agroecosystems 64, 237–256.
Nitrate leaching in temperate agroecosystems: sources, factors and mitigating strategies.Crossref | GoogleScholarGoogle Scholar |

Diamantini, E., Lutz, S. R., Mallucci, S., Majone, B., Merz, R., and Bellin, A. (2018). Driver detection of water quality trends in three large European river basins. The Science of the Total Environment 612, 49–62.
Driver detection of water quality trends in three large European river basins.Crossref | GoogleScholarGoogle Scholar | 28846904PubMed |

Duncan, R. (2014). Regulating agricultural land use to manage water quality: the challenges for science and policy in enforcing limits on non-point source pollution in New Zealand. Land Use Policy 41, 378–387.
Regulating agricultural land use to manage water quality: the challenges for science and policy in enforcing limits on non-point source pollution in New Zealand.Crossref | GoogleScholarGoogle Scholar |

Dupas, R., Jomaa, S., Musolff, A., Borchardt, D., and Rode, M. (2016). Disentangling the influence of hydroclimatic patterns and agricultural management on river nitrate dynamics from sub-hourly to decadal time scales. The Science of the Total Environment 571, 791–800.
Disentangling the influence of hydroclimatic patterns and agricultural management on river nitrate dynamics from sub-hourly to decadal time scales.Crossref | GoogleScholarGoogle Scholar | 27422723PubMed |

Dymond, J. R., Ausseil, A.-G., Parfitt, R. L., Herzig, A., and McDowell, R. W. (2013). Nitrate and phosphorus leaching in New Zealand: a national perspective. New Zealand Journal of Agricultural Research 56, 49–59.
Nitrate and phosphorus leaching in New Zealand: a national perspective.Crossref | GoogleScholarGoogle Scholar |

Foote, K. J., Joy, M. K., and Death, R. G. (2015). New Zealand dairy farming: milking our environment for all its worth. Environmental Management 56, 709–720.
New Zealand dairy farming: milking our environment for all its worth.Crossref | GoogleScholarGoogle Scholar | 25900603PubMed |

Gascuel-Odoux, C., Aurousseau, P., Durand, P., Ruiz, L., and Molenat, J. (2010). The role of climate on inter-annual variation in stream nitrate fluxes and concentrations. The Science of the Total Environment 408, 5657–5666.
The role of climate on inter-annual variation in stream nitrate fluxes and concentrations.Crossref | GoogleScholarGoogle Scholar | 19497610PubMed |

Gravelle, J. A., Ice, G., Link, T. E., and Cook, D. L. (2009). Nutrient concentration dynamics in an inland Pacific Northwest watershed before and after timber harvest. Forest Ecology and Management 257, 1663–1675.
Nutrient concentration dynamics in an inland Pacific Northwest watershed before and after timber harvest.Crossref | GoogleScholarGoogle Scholar |

Hamill, K. D., and McBride, G. B. (2003). River water quality trends and increased dairying in Southland, New Zealand. New Zealand Journal of Marine and Freshwater Research 37, 323–332.
River water quality trends and increased dairying in Southland, New Zealand.Crossref | GoogleScholarGoogle Scholar |

Harding, L. W., Mallonee, M. E., Perry, E. S., Miller, W. D., Adolf, J. E., Gallegos, C. L., and Paerl, H. W. (2019). Long-term trends, current status, and transitions of water quality in Chesapeake Bay. Scientific Reports 9, 6709.
Long-term trends, current status, and transitions of water quality in Chesapeake Bay.Crossref | GoogleScholarGoogle Scholar | 31040300PubMed |

Harrigan, S., Murphy, C., Hall, J., Wilby, R. L., and Sweeney, J. (2014). Attribution of detected changes in streamflow using multiple working hypotheses. Hydrology and Earth System Sciences 18, 1935–1952.
Attribution of detected changes in streamflow using multiple working hypotheses.Crossref | GoogleScholarGoogle Scholar |

Helsel, D. R. (2011). ‘Statistics for Censored Environmental Data using Minitab and R.’ (Wiley.)

Hirsch, R. M., Slack, J. R., and Smith, R. A. (1982). Techniques of trend analysis for monthly water quality data. Water Resources Research 18, 107–121.
Techniques of trend analysis for monthly water quality data.Crossref | GoogleScholarGoogle Scholar |

Hirsch, R. M., Alexander, R. B., and Smith, R. A. (1991). Selection of methods for the detection and estimation of trends in water quality. Water Resources Research 27, 803–813.
Selection of methods for the detection and estimation of trends in water quality.Crossref | GoogleScholarGoogle Scholar |

Hirsch, R. M., Archfield, S. A., and De Cicco, L. A. (2015). A bootstrap method for estimating uncertainty of water quality trends. Environmental Modelling & Software 73, 148–166.
A bootstrap method for estimating uncertainty of water quality trends.Crossref | GoogleScholarGoogle Scholar |

Howden, N. J. K., and Burt, T. P. (2009). Statistical analysis of nitrate concentrations from the Rivers Frome and Piddle (Dorset, UK) for the period 1965–2007. Ecohydrology 2, 55–65.
Statistical analysis of nitrate concentrations from the Rivers Frome and Piddle (Dorset, UK) for the period 1965–2007.Crossref | GoogleScholarGoogle Scholar |

Hughes, A. O., and Quinn, J. M. (2019). The effect of forestry management activities on stream water quality within a headwater plantation Pinus radiata forest. Forest Ecology and Management 439, 41–54.
The effect of forestry management activities on stream water quality within a headwater plantation Pinus radiata forest.Crossref | GoogleScholarGoogle Scholar |

Hyndman, R. J., and Athanasopoulos, G. (2021). ‘Forecasting: Principles and Practice.’ (OTexts: Melbourne, Vic., Australia.)

Jackson, D. A. (1993). Stopping rules in principal components analysis: a comparison of heuristical and statistical approaches. Ecology 74, 2204–2214.
Stopping rules in principal components analysis: a comparison of heuristical and statistical approaches.Crossref | GoogleScholarGoogle Scholar |

Joy, M. K., Foote, K. J., McNie, P., and Piria, M. (2019). Decline in New Zealand’s freshwater fish fauna: effect of land use. Marine and Freshwater Research 70, 114–124.
Decline in New Zealand’s freshwater fish fauna: effect of land use.Crossref | GoogleScholarGoogle Scholar |

Julian, J. P., de Beurs, K. M., Owsley, B., Davies-Colley, R. J., and Ausseil, A.-G. E. (2017). River water quality changes in New Zealand over 26 years: response to land use intensity. Hydrology and Earth System Sciences 21, 1149–1171.
River water quality changes in New Zealand over 26 years: response to land use intensity.Crossref | GoogleScholarGoogle Scholar |

Larned, S. T., Scarsbrook, M. R., Snelder, T., Norton, N. J., and Biggs, B. J. F. (2004). Water quality in low-elevation streams and rivers of New Zealand. New Zealand Journal of Marine and Freshwater Research 38, 347–366.
Water quality in low-elevation streams and rivers of New Zealand.Crossref | GoogleScholarGoogle Scholar |

Larned, S., Snelder, T., Unwin, M., and McBride, G. (2016). Water quality in New Zealand rivers: current state and trends. New Zealand Journal of Marine and Freshwater Research 50, 389–417.
Water quality in New Zealand rivers: current state and trends.Crossref | GoogleScholarGoogle Scholar |

Ledgard, S. F., Luo, J., and Monaghan, R. M. (2011). Managing mineral N leaching in grassland systems. In ‘Grassland Productivity and Ecosystem Services’. (Eds G. Lemaire, J. Hodgson, and A. Chabbi.) pp. 83–91. (CAB International.)
| Crossref |

Legendre, P., and Legendre, L. (1998). ‘Numerical Ecology.’ (Elsevier: Amsterdam, Netherlands.)

Livestock Improvement Corporation Limited and DairyNZ Limited (2018). New Zealand Dairy Statistics 2017–18, DNZ30–DNZ007, LIC & DNZ Limited, New Zealand.

Luo, P., He, B., Takara, K., Razafindrabe, B. H., Nover, D., and Yamashiki, Y. (2011). Spatiotemporal trend analysis of recent river water quality conditions in Japan. Journal of Environmental Monitoring 13, 2819–2829.
Spatiotemporal trend analysis of recent river water quality conditions in Japan.Crossref | GoogleScholarGoogle Scholar | 21842064PubMed |

MacLeod, C. J., and Moller, H. (2006). Intensification and diversification of New Zealand agriculture since 1960: An evaluation of current indicators of land use change. Agriculture, Ecosystems & Environment 115, 201–218.
Intensification and diversification of New Zealand agriculture since 1960: An evaluation of current indicators of land use change.Crossref | GoogleScholarGoogle Scholar |

Makowski, D., Ben-Shachar, M. S., Chen, S. H. A., and Lüdecke, D. (2019). Indices of effect existence and significance in the Bayesian framework. Frontiers in Psychology 10, 2767.
Indices of effect existence and significance in the Bayesian framework.Crossref | GoogleScholarGoogle Scholar | 31920819PubMed |

Mantel, N. (1967). The detection of disease clustering and a generalized regression approach. Cancer Research 27, 209–220.
| 6018555PubMed |

McDowell, R. W., and Wilcock, R. J. (2008). Water quality and the effects of different pastoral animals. New Zealand Veterinary Journal 56, 289–296.
Water quality and the effects of different pastoral animals.Crossref | GoogleScholarGoogle Scholar |

McDowell, R. W., Hedley, M. J., Pletnyakov, P., Rissmann, C., Catto, W., and Patrick, W. (2019). Why are median phosphorus concentrations improving in New Zealand streams and rivers? Journal of the Royal Society of New Zealand 49, 143–170.
Why are median phosphorus concentrations improving in New Zealand streams and rivers?Crossref | GoogleScholarGoogle Scholar |

Mellander, P.-E., Jordan, P., Bechmann, M., Fovet, O., Shore, M. M., McDonald, N. T., and Gascuel-Odoux, C. (2018). Integrated climate-chemical indicators of diffuse pollution from land to water. Scientific Reports 8, 944.
Integrated climate-chemical indicators of diffuse pollution from land to water.Crossref | GoogleScholarGoogle Scholar | 29343796PubMed |

Merz, B., Vorogushyn, S., Uhlemann, S., Delgado, J., and Hundecha, Y. (2012). More efforts and scientific rigour are needed to attribute trends in flood time series. Hydrology and Earth System Sciences 16, 1379–1387.
More efforts and scientific rigour are needed to attribute trends in flood time series.Crossref | GoogleScholarGoogle Scholar |

Ministry for the Environment (2012). ‘Land-Use and Carbon Analysis System: Satellite Imagery Interpretation Guide for Land-Use Classes’, 2nd edn. (MFE, Wellington, New Zealand.)

Ministry for the Environment and Statistics New Zealand (2017). ‘Our Fresh Water 2017.’ (MFE & StasNZ: Wellington, New Zealand.) Available at https://www.mfe.govt.nz/sites/default/files/media/Environmental%20reporting/our-fresh-water-2017_1.pdf

Ministry for the Environment and Statistics New Zealand (2018). New Zealand’s Environmental Reporting Series: Our Land 2018. ME 1350. (MFE and StatsNZ: Wellington, New Zealand.) Available at https://www.mfe.govt.nz/publications/environmental-reporting/our-land-2018

Ministry for the Environment and Statistics New Zealand (2019). Environment Aotearoa 2019. Environmental Reporting Series. (MFE and StatsNZ: Wellington, New Zealand.) Available at https://www.mfe.govt.nz/sites/default/files/media/Environmental%20reporting/environment-aotearoa-2019.pdf

Monaghan, R. M., Hedley, M. J., Di, H. J., McDowell, R. W., Cameron, K. C., and Ledgard, S. F. (2007). Nutrient management in New Zealand pastures – recent developments and future issues. New Zealand Journal of Agricultural Research 50, 181–201.
Nutrient management in New Zealand pastures – recent developments and future issues.Crossref | GoogleScholarGoogle Scholar |

Monaghan, R. M., Carey, P. L., Wilcock, R. J., Drewry, J. J., Houlbrooke, D. J., Quinn, J. M., and Thorrold, B. S. (2009). Linkages between land management activities and stream water quality in a border dyke-irrigated pastoral catchment. Agriculture, Ecosystems & Environment 129, 201–211.
Linkages between land management activities and stream water quality in a border dyke-irrigated pastoral catchment.Crossref | GoogleScholarGoogle Scholar |

Monaghan, R. M., Houlbrooke, D. J., and Smith, L. C. (2010). The use of low-rate sprinkler application systems for applying farm dairy effluent to land to reduce contaminant transfers. New Zealand Journal of Agricultural Research 53, 389–402.
The use of low-rate sprinkler application systems for applying farm dairy effluent to land to reduce contaminant transfers.Crossref | GoogleScholarGoogle Scholar |

Monaghan, R. M., Basher, L., Spiekermann, R., Smith, R., Dymond, J. R., Muirhead, R., Burger, D., and McDowell, R. (2021). Quantifying contaminant losses to water from pastoral land uses in New Zealand II. The effects of some farm mitigation actions over the past two decades. New Zealand Journal of Agricultural Research 64, 365–389.
Quantifying contaminant losses to water from pastoral land uses in New Zealand II. The effects of some farm mitigation actions over the past two decades.Crossref | GoogleScholarGoogle Scholar |

Morse, N. B., and Wollheim, W. M. (2014). Climate variability masks the impacts of land use change on nutrient export in a suburbanizing watershed. Biogeochemistry 121, 45–59.
Climate variability masks the impacts of land use change on nutrient export in a suburbanizing watershed.Crossref | GoogleScholarGoogle Scholar |

Mosley, M. P. (2000). Regional differences in the effects of El Niño and La Niña on low flows and floods. Hydrological Sciences Journal 45, 249–267.
Regional differences in the effects of El Niño and La Niña on low flows and floods.Crossref | GoogleScholarGoogle Scholar |

Murphy, J. C. (2020). Changing suspended sediment in United States rivers and streams: linking sediment trends to changes in land use/cover, hydrology and climate. Hydrology and Earth System Sciences 24, 991–1010.
Changing suspended sediment in United States rivers and streams: linking sediment trends to changes in land use/cover, hydrology and climate.Crossref | GoogleScholarGoogle Scholar |

Murphy, J., and Sprague, L. (2019). Water-quality trends in US rivers: exploring effects from streamflow trends and changes in watershed management. The Science of the Total Environment 656, 645–658.
Water-quality trends in US rivers: exploring effects from streamflow trends and changes in watershed management.Crossref | GoogleScholarGoogle Scholar | 30529968PubMed |

New Zealand Government (2014). National Policy Statement for Freshwater Management 2014. (New Zealand Government.)

New Zealand Government (2017). National Policy Statement for Freshwater Management 2014 (amended 2017). (Ministry for the Environment, New Zealand Government.) Available at http://www.mfe.govt.nz/publications/rma/nps-freshwater-management-2014/nps-freshwater-management-jul-14.pdf

New Zealand Government (2020a). National Policy Statement for Freshwater Management 2020. (Ministry for the Environment, New Zealand Government.) Available at http://www.mfe.govt.nz/publications/rma/nps-freshwater-management-2014/nps-freshwater-management-jul-14.pdf

New Zealand Government (2020b). New Zealand’s Greenhouse Gas Inventory: 1990–2018. MFE 1496. (Ministry for the Environment: Wellington, New Zealand.) Available at https://www.mfe.govt.nz/sites/default/files/media/Climate%20Change/new-zealands-greenhouse-gas-inventory-1990-2018-vol-1.pdf

Newsome, P., Shepard, J., Pairman, D., Belliss, S., and Manderson, A. (2018). Establishing New Zealands LUCAS 2016 Land Use Map. Contract Report LC3369. Manaaki Whenua–Landcare Research, New Zealand.

Oelsner, G. P., Sprague, L. A., Murphy, J. C., Zuellig, R. E., Johnson, H. M., Ryberg, K. R., Falcone, J. A., Stets, E. G., Vecchia, A. V., Riskin, M. L., De Cicco, L. A., Mills, T. J., and Farmer, W. H. (2017). Water-quality trends in the Nation’s rivers and streams, 1972–2012 – data preparation, statistical methods, and trend results (ver. 2.0, October 2017). Scientific Investigations Report 2017–5006. (US Geological Survey: Reston, VA, USA.) Available at https://pubs.er.usgs.gov/publication/sir20175006

Parker, W. J. (1998). Standardisation between livestock classes: the use and misuse of the stock unit system. In ‘Proceedings of the Conference New Zealand Grassland Association’, 20–22 October 1998, Nelson, New Zealand. pp. 243–248. (New Zealand Grassland Association.) Available at https://www.grassland.org.nz/publications/nzgrassland_publication_247.pdf

Ryberg, K. R. (2017). Structural equation model of total phosphorus loads in the Red River of the North Basin, USA and Canada. Journal of Environmental Quality 46, 1072–1080.
Structural equation model of total phosphorus loads in the Red River of the North Basin, USA and Canada.Crossref | GoogleScholarGoogle Scholar | 28991977PubMed |

Ryberg, K. R., Blomquist, J. D., Sprague, L. A., Sekellick, A. J., and Keisman, J. (2018). Modeling drivers of phosphorus loads in Chesapeake Bay tributaries and inferences about long-term change. The Science of the Total Environment 616–617, 1423–1430.
Modeling drivers of phosphorus loads in Chesapeake Bay tributaries and inferences about long-term change.Crossref | GoogleScholarGoogle Scholar | 29102189PubMed |

Salinger, M. J., and Mullan, A. B. (1999). New Zealand climate: temperature and precipitation variations and their links with atmospheric circulation. International Journal of Climatology 19, 1049–1071.
New Zealand climate: temperature and precipitation variations and their links with atmospheric circulation.Crossref | GoogleScholarGoogle Scholar |

Scarsbrook, M. R., and Melland, A. R. (2015). Dairying and water-quality issues in Australia and New Zealand. Animal Production Science 55, 856–868.
Dairying and water-quality issues in Australia and New Zealand.Crossref | GoogleScholarGoogle Scholar |

Scarsbrook, M. R., McBride, C. G., McBride, G. B., and Bryers, G. G. (2003). Effects of climate variability on rivers: consequences for long term water quality analysis. Journal of the American Water Resources Association 39, 1435–1447.
Effects of climate variability on rivers: consequences for long term water quality analysis.Crossref | GoogleScholarGoogle Scholar |

Smith, W., and Montgomery, H. (2004). Revolution or evolution? New Zealand agriculture since 1984. GeoJournal 59, 107–118.
Revolution or evolution? New Zealand agriculture since 1984.Crossref | GoogleScholarGoogle Scholar |

Snelder, T. H., and Biggs, B. J. F. (2002). Multi-scale river environment classification for water resources management. Journal of the American Water Resources Association 38, 1225–1239.
Multi-scale river environment classification for water resources management.Crossref | GoogleScholarGoogle Scholar |

Snelder, T. H., Larned, S. T., Fraser, C., and De Malmanche, S. (2021). Effect of climate variability on water quality trends in New Zealand rivers. Marine and Freshwater Research. [Published online 30 September 2021].
| Crossref |

Suthanthangjai, M., Moore, K., Steel, G., and Hughey, K. F. (2013). Tracking New Zealanders environmental perceptions: a comparison of responses from two survey approaches. The International Journal of Science in Society 4, 25–40.
Tracking New Zealanders environmental perceptions: a comparison of responses from two survey approaches.Crossref | GoogleScholarGoogle Scholar |

Trafford, G., and Trafford, S. (2011). ‘Farm Technical Manual.’ (Caxton Press: Christchurch, New Zealand.)

Turner, R. E., and Rabalais, N. N. (2003). Linking landscape and water quality in the Mississippi River Basin for 200 years. Bioscience 53, 563–572.
Linking landscape and water quality in the Mississippi River Basin for 200 years.Crossref | GoogleScholarGoogle Scholar |

Ummenhofer, C. C., Sen Gupta, A., and England, M. H. (2009). Causes of late twentieth-century trends in New Zealand precipitation. Journal of Climate 22, 3–19.
Causes of late twentieth-century trends in New Zealand precipitation.Crossref | GoogleScholarGoogle Scholar |

Wiering, M., Boezeman, D., and Crabbé, A. (2020). The water framework directive and agricultural diffuse pollution: fighting a running battle? Water 12, 1447.
The water framework directive and agricultural diffuse pollution: fighting a running battle?Crossref | GoogleScholarGoogle Scholar |

Wilcock, R. J., Monaghan, R. M., Quinn, J. M., Srinivasan, M. S., Houlbrooke, D. J., Duncan, M. J., Wright-Stow, A. E., and Scarsbrook, M. R. (2013). Trends in water quality of five dairy farming streams in response to adoption of best practice and benefits of long-term monitoring at the catchment scale. Marine and Freshwater Research 64, 401–412.
Trends in water quality of five dairy farming streams in response to adoption of best practice and benefits of long-term monitoring at the catchment scale.Crossref | GoogleScholarGoogle Scholar |

Wright-Stow, A. E., and Wilcock, R. J. (2017). Responses of stream macroinvertebrate communities and water quality of five dairy farming streams following adoption of mitigation practices. New Zealand Journal of Marine and Freshwater Research 51, 127–145.
Responses of stream macroinvertebrate communities and water quality of five dairy farming streams following adoption of mitigation practices.Crossref | GoogleScholarGoogle Scholar |

Zeldis, J. R., Howard-Williams, C., Carter, C. M., and Schiel, D. R. (2008). ENSO and riverine control of nutrient loading, phytoplankton biomass and mussel aquaculture yield in Pelorus Sound, New Zealand. Marine Ecology Progress Series 371, 131–142.
ENSO and riverine control of nutrient loading, phytoplankton biomass and mussel aquaculture yield in Pelorus Sound, New Zealand.Crossref | GoogleScholarGoogle Scholar |