Environment - Urban stream water quality trends at monitored sited in Auckland, Wellington, and Christchurch 2008–2015

Zinc and copper are heavy metals that can accumulate in sediments, shellfish, and other aquatic organisms. Metals can reach toxic levels in organisms making them unsafe to eat and can be toxic to aquatic life.
Nitrogen and phosphorus are nutrients that can cause excessive algal growth. Ammonical nitrogen and nitrate-nitrogen can be toxic to aquatic life if concentrations in streams are high enough.
E.coli is an indicator of disease-causing organisms, which may affect human health and recreational values in streams.

Figure.NZ undertook simple calculations on the original csv data (sum by outcome and indicator) to mirror the analysis undertaken for the Environmental Reporting Series (see http://stats.govt.nz/browse_for_stats/environment/environmental-reporting-series/environmental-indicators/Home/Fresh%20water/urban-stream-water-quality.aspx Figure 1)

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Auckland Council, Greater Wellington Regional Council, and Christchurch City Council collect urban stream water samples monthly at fixed locations and send them to a laboratory for chemical and bacterial analysis.