Figure 1. National and regional summary statistics for state and trends in key indicators of groundwater quality based on all data collected from 1995 to 2008 (cf. Section 2.2). Numbers above X axes show the number of sites at which state and trend statistics could be calculated for the parameter in question for the region of interest. Colour coding for box-whisker plots shows national-level statistics (blue) or regional-level statistics (red).
Read a description of this figure
(Figure 1a) Upper graph. Percentage of New Zealand monitoring sites at which median concentrations calculated for the entire period from 1995 to 2008 exceed water quality guidelines for nitrate-nitrogen.
| Council | n1 | DWSNZ | ANZECC | ||
|---|---|---|---|---|---|
| GV2 = 11.3 mg/L | TV3 = 7.2 mg/L | ||||
| # Sites Exceeding | % Sites Exceeding4 | # Sites Exceeding | % Sites Exceeding4 | ||
| Auckland | 24 | 0 | 0.0 | 1 | 4.2 |
| Bay of Plenty | 54 | 0 | 0.0 | 0 | 0.0 |
| Canterbury | 279 | 14 | 5.0 | 46 | 16.5 |
| Gisborne | 0 | ||||
| Hawkes Bay | 45 | 0 | 0.0 | 0 | 0.0 |
| Manawatu-Wanganui | 24 | 3 | 12.5 | 4 | 16.7 |
| Marlborough | 24 | 0 | 0.0 | 1 | 4.2 |
| Northland | 39 | 0 | 0.0 | 5 | 12.8 |
| Otago | 98 | 4 | 4.1 | 7 | 7.1 |
| Southland | 52 | 1 | 1.9 | 7 | 13.5 |
| Taranaki | 71 | 5 | 7.0 | 8 | 11.3 |
| Tasman | 16 | 2 | 12.5 | 2 | 12.5 |
| Waikato | 115 | 15 | 13.0 | 33 | 28.7 |
| Wellington | 71 | 0 | 0.0 | 7 | 9.9 |
| West Coast | 8 | 0 | 0.0 | 0 | 0.0 |
| All | 920 | 44 | 4.8 | 121 | 13.2 |
1 Number of sites where median could be calculated (i.e. there was at least one sample result from that site within the time period of interest).
2 Aesthetic Guideline Value specified in DWSNZ 2005.
3 Trigger Value for toxicity and/or ecosystem protection (95% level) specified in ANZECC 2000.
4 Percentage of monitoring sites at which median exceeds the water quality standard, relative to the total number of sites for which a median could be calculated for the parameter in question within the time period of interest.
(Figure 1a) Lower graph. Percentiles by region for nitrate-nitrogen for period 1995-2008
| Council | n | Percentiles (mg/L) | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 24 | 0.001 | 0.001 | 0.003 | 0.071 | 5.758 |
| Bay of Plenty | 54 | 0.001 | 0.005 | 0.068 | 0.370 | 3.327 |
| Canterbury | 279 | 0.100 | 1.100 | 3.400 | 6.150 | 11.455 |
| Gisborne | 0 | |||||
| Hawkes Bay | 45 | 0.002 | 0.005 | 0.015 | 0.190 | 4.460 |
| Manawatu-Wanganui | 24 | 0.003 | 0.070 | 0.115 | 0.741 | 12.850 |
| Marlborough | 24 | 0.002 | 0.088 | 0.633 | 1.724 | 5.679 |
| Northland | 39 | 0.001 | 0.008 | 0.168 | 3.770 | 8.581 |
| Otago | 98 | 0.004 | 0.061 | 0.665 | 2.890 | 8.073 |
| Southland | 52 | 0.005 | 1.375 | 3.400 | 5.420 | 9.945 |
| Taranaki | 71 | 0.002 | 1.243 | 2.065 | 4.335 | 11.700 |
| Tasman | 16 | 0.007 | 0.288 | 1.725 | 4.125 | 14.250 |
| Waikato | 115 | 0.084 | 1.680 | 4.160 | 7.985 | 15.575 |
| Wellington | 71 | 0.000 | 0.002 | 0.515 | 3.273 | 10.069 |
| West Coast | 8 | 0.350 | 0.885 | 1.075 | 2.300 | 3.590 |
| All | 920 | 0.000 | 0.100 | 1.700 | 4.700 | 11.000 |
(Figure 1b) Upper graph. Total number of monitoring sites (n) at which site-specific trend tests for nitrate-nitrogen could be performed for the time period 1995 to 2008 (i.e. the parameter had been measured at least three times between 1995 and 2008). Also shown are the number and percentage of sites at which significant increasing or decreasing trends were detected (INCR or DECR, respectively) and the number of sites at which no significant trend was detected (N).
| Region | n | INCR | DECR | N | %INCR | %DECR | %N |
|---|---|---|---|---|---|---|---|
| Auckland | 21.0 | 3.0 | 6.0 | 12.0 | 14.3 | 28.6 | 57.1 |
| Bay of Plenty | 53.0 | 3.0 | 4.0 | 46.0 | 5.7 | 7.5 | 86.8 |
| Canterbury | 272.0 | 81.0 | 16.0 | 175.0 | 29.8 | 5.9 | 64.3 |
| Hawke's Bay | 45.0 | 8.0 | 4.0 | 33.0 | 17.8 | 8.9 | 73.3 |
| Manawatu | 21.0 | 2.0 | 4.0 | 15.0 | 9.5 | 19.0 | 71.4 |
| Marlborough | 23.0 | 5.0 | 2.0 | 16.0 | 21.7 | 8.7 | 69.6 |
| Northland | 37.0 | 3.0 | 3.0 | 31.0 | 8.1 | 8.1 | 83.8 |
| Otago | 98.0 | 12.0 | 11.0 | 75.0 | 12.2 | 11.2 | 76.5 |
| Southland | 41.0 | 8.0 | 5.0 | 28.0 | 19.5 | 12.2 | 68.3 |
| Taranaki | 70.0 | 5.0 | 9.0 | 56.0 | 7.1 | 12.9 | 80.0 |
| Tasman | 16.0 | 4.0 | 3.0 | 9.0 | 25.0 | 18.8 | 56.3 |
| Waikato | 110.0 | 36.0 | 22.0 | 52.0 | 32.7 | 20.0 | 47.3 |
| Wellington | 71.0 | 4.0 | 14.0 | 53.0 | 5.6 | 19.7 | 74.6 |
| West Coast | 8.0 | 4.0 | 0.0 | 4.0 | 50.0 | 0.0 | 50.0 |
(Figure1b) Lower graph. Percentiles by region for trends in nitrate-nitrogen for period 1995-2008
| Council | n | Percentiles (mg/L) | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 21 | -0.001 | 0.000 | 0.000 | 0.066 | 0.432 |
| Bay of Plenty | 53 | -0.502 | -0.050 | -0.001 | 0.240 | 0.299 |
| Canterbury | 272 | -0.174 | 0.015 | 0.103 | 0.242 | 0.620 |
| Gisborne | 0 | |||||
| Hawkes Bay | 45 | -0.014 | -0.002 | 0.007 | 0.037 | 0.154 |
| Manawatu-Wanganui | 21 | -0.332 | -0.227 | 0.000 | 0.006 | 0.010 |
| Marlborough | 23 | -0.015 | 0.001 | 0.077 | 0.311 | 0.752 |
| Northland | 37 | -0.613 | -0.020 | 0.002 | 0.191 | 0.384 |
| Otago | 98 | -0.289 | -0.064 | 0.003 | 0.091 | 0.275 |
| Southland | 41 | -0.227 | -0.100 | 0.093 | 0.286 | 0.378 |
| Taranaki | 70 | -0.511 | -0.075 | -0.011 | 0.223 | 1.000 |
| Tasman | 16 | -0.433 | -0.162 | 0.005 | 0.286 | 0.431 |
| Waikato | 110 | -0.682 | -0.161 | 0.041 | 0.245 | 0.971 |
| Wellington | 71 | -0.435 | -0.286 | -0.072 | 0.000 | 0.084 |
| West Coast | 8 | 0.012 | 0.042 | 0.120 | 0.326 | 0.667 |
| All | 886 | -0.423 | -0.042 | 0.029 | 0.203 | 0.749 |
(Figure 1c) Upper graph. Percentage of New Zealand monitoring sites at which median concentrations calculated for the entire period from 1995 to 2008 exceed water quality guidelines for ammoniacal nitrogen.
| Council | n1 | DWSNZ | ANZECC | ||
|---|---|---|---|---|---|
| GV2 = 1.5 mg/L | TV3 = 0.9 mg/L | ||||
| # Sites Exceeding | % Sites Exceeding4 | # Sites Exceeding | % Sites Exceeding4 | ||
| Auckland | 24 | 0 | 0.0 | 2 | 8.3 |
| Bay of Plenty | 54 | 1 | 1.9 | 4 | 7.4 |
| Canterbury | 279 | 3 | 1.1 | 4 | 1.4 |
| Gisborne | 0 | ||||
| Hawkes Bay | 45 | 7 | 15.6 | 8 | 17.8 |
| Manawatu-Wanganui | 27 | 8 | 29.6 | 9 | 33.3 |
| Marlborough | 23 | 0 | 0.0 | 0 | 0.0 |
| Northland | 40 | 1 | 2.5 | 2 | 5.0 |
| Otago | 98 | 3 | 3.1 | 4 | 4.1 |
| Southland | 47 | 0 | 0.0 | 0 | 0.0 |
| Taranaki | 71 | 3 | 4.2 | 4 | 5.6 |
| Tasman | 16 | 0 | 0.0 | 0 | 0.0 |
| Waikato | 115 | 1 | 0.9 | 1 | 0.9 |
| Wellington | 71 | 6 | 8.5 | 9 | 12.7 |
| West Coast | 8 | 0 | 0.0 | 0 | 0.0 |
| All | 918 | 35 | 3.8 | 49 | 5.3 |
1 Number of sites where median could be calculated (i.e. there was at least one sample result from that site within the time period of interest).
2 Aesthetic Guideline Value specified in DWSNZ 2005.
3 Trigger Value for toxicity and/or ecosystem protection (95% level) specified in ANZECC 2000.
4 Percentage of monitoring sites at which median exceeds the water quality standard, relative to the total number of sites for which a median could be calculated for the parameter in question within the time period of interest.
(Figure 1c) Lower graph. Percentiles by region for ammoniacal nitrogen for period 1995-2008
| Council | n | Percentiles (mg/L) | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 24 | 0.001 | 0.009 | 0.145 | 0.290 | 1.201 |
| Bay of Plenty | 54 | 0.000 | 0.002 | 0.020 | 0.152 | 1.008 |
| Canterbury | 279 | 0.004 | 0.006 | 0.008 | 0.011 | 0.069 |
| Gisborne | 0 | |||||
| Hawkes Bay | 45 | 0.000 | 0.007 | 0.089 | 0.570 | 3.391 |
| Manawatu-Wanganui | 27 | 0.013 | 0.030 | 0.250 | 1.850 | 4.260 |
| Marlborough | 23 | 0.000 | 0.000 | 0.005 | 0.010 | 0.152 |
| Northland | 40 | 0.000 | 0.000 | 0.020 | 0.085 | 0.726 |
| Otago | 98 | 0.002 | 0.005 | 0.010 | 0.024 | 0.667 |
| Southland | 47 | 0.000 | 0.001 | 0.005 | 0.013 | 0.045 |
| Taranaki | 71 | 0.001 | 0.013 | 0.102 | 1.120 | 5.270 |
| Tasman | 16 | 0.000 | 0.001 | 0.004 | 0.009 | 0.040 |
| Waikato | 115 | 0.000 | 0.002 | 0.010 | 0.070 | 6.080 |
| Wellington | 71 | 0.000 | 0.001 | 0.020 | 0.290 | 4.860 |
| West Coast | 8 | 0.000 | 0.000 | 0.000 | 0.003 | 0.021 |
| All | 918 | 0.000 | 0.001 | 0.010 | 0.030 | 0.970 |
(Figure 1d) Upper graph. Total number of monitoring sites (n) at which site-specific trend tests for ammoniacal-nitrogen could be performed for the time period 1995 to 2008 (i.e. the parameter had been measured at least three times between 1995 and 2008).
| Region | n | INCR | DECR | N | %INCR | %DECR | %N |
|---|---|---|---|---|---|---|---|
| Auckland | 22.0 | 0.0 | 4.0 | 18.0 | 0.0 | 18.2 | 81.8 |
| Bay of Plenty | 53.0 | 6.0 | 3.0 | 44.0 | 11.3 | 5.7 | 83.0 |
| Canterbury | 275.0 | 72.0 | 4.0 | 199.0 | 26.2 | 1.5 | 72.4 |
| Hawke's Bay | 45.0 | 2.0 | 10.0 | 33.0 | 4.4 | 22.2 | 73.3 |
| Manawatu | 25.0 | 3.0 | 1.0 | 21.0 | 12.0 | 4.0 | 84.0 |
| Marlborough | 19.0 | 1.0 | 0.0 | 18.0 | 5.3 | 0.0 | 94.7 |
| Northland | 38.0 | 0.0 | 4.0 | 34.0 | 0.0 | 10.5 | 89.5 |
| Otago | 89.0 | 7.0 | 8.0 | 74.0 | 7.9 | 9.0 | 83.1 |
| Southland | 36.0 | 0.0 | 0.0 | 36.0 | 0.0 | 0.0 | 100.0 |
| Taranaki | 70.0 | 5.0 | 12.0 | 53.0 | 7.1 | 17.1 | 75.7 |
| Tasman | 15.0 | 1.0 | 0.0 | 14.0 | 6.7 | 0.0 | 93.3 |
| Waikato | 82.0 | 4.0 | 4.0 | 74.0 | 4.9 | 4.9 | 90.2 |
| Wellington | 67.0 | 9.0 | 15.0 | 43.0 | 13.4 | 22.4 | 64.2 |
| West Coast | 8.0 | 0.0 | 0.0 | 8.0 | 0.0 | 0.0 | 100.0 |
(Figure 1d) Lower graph. Percentiles by region for trends in ammoniacal nitrogen for period 1995-2008
| Council | n | Percentiles (mg/L) | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 22 | -0.013 | -0.008 | -0.006 | -0.005 | -0.002 |
| Bay of Plenty | 53 | -0.196 | -0.017 | 0.000 | 0.003 | 0.025 |
| Canterbury | 275 | -0.002 | 0.001 | 0.001 | 0.001 | 0.002 |
| Gisborne | 0 | |||||
| Hawkes Bay | 45 | -0.080 | -0.002 | -0.001 | 0.000 | 0.004 |
| Manawatu-Wanganui | 25 | -0.007 | 0.003 | 0.035 | 0.081 | 0.126 |
| Marlborough | 19 | 0.001 | 0.001 | 0.001 | 0.001 | 0.001 |
| Northland | 38 | -0.036 | -0.016 | -0.006 | -0.005 | -0.004 |
| Otago | 89 | -0.003 | -0.001 | 0.000 | 0.031 | 0.091 |
| Southland | 36 | |||||
| Taranaki | 70 | -0.037 | -0.001 | -0.001 | 0.004 | 0.026 |
| Tasman | 15 | 0.001 | 0.001 | 0.001 | 0.001 | 0.001 |
| Waikato | 82 | -0.007 | -0.002 | 0.002 | 0.021 | 0.029 |
| Wellington | 67 | -0.021 | -0.008 | -0.003 | 0.000 | 0.012 |
| West Coast | 8 | |||||
| All | 844 | -0.026 | -0.002 | 0.001 | 0.001 | 0.031 |
(Figure 1e) Upper graph. Percentage of New Zealand monitoring sites at which median concentrations calculated for the entire period from 1995 to 2008 exceed water quality guidelines for E. coli.
| Council | n1 | DWSNZ | ANZECC | ||
|---|---|---|---|---|---|
| MAV2= 1 cfu/100 ml | TV3 = 100 cfu/100 ml | ||||
| # Sites Exceeding | % Sites Exceeding4 | # Sites Exceeding | % Sites Exceeding4 | ||
| Auckland | 21 | 7 | 33.3 | 2 | 9.5 |
| Bay of Plenty5 | 20 | 0 | 0.0 | 0 | 0.0 |
| Canterbury | 272 | 42 | 15.4 | 2 | 0.7 |
| Gisborne | 0 | ||||
| Hawkes Bay | 35 | 5 | 14.3 | 2 | 5.7 |
| Manawatu-Wanganui | 0 | ||||
| Marlborough | 9 | 1 | 11.1 | 0 | 0.0 |
| Northland | 40 | 10 | 25.0 | 0 | 0.0 |
| Otago | 62 | 19 | 30.6 | 2 | 3.2 |
| Southland | 43 | 3 | 7.0 | 1 | 2.3 |
| Taranaki | 67 | 47 | 70.1 | 6 | 9.0 |
| Tasman | 0 | ||||
| Waikato | 64 | 16 | 25.0 | 1 | 1.6 |
| Wellington | 60 | 11 | 18.3 | 1 | 1.7 |
| West Coast | 8 | 1 | 12.5 | 0 | 0.0 |
| All | 701 | 162 | 23.1 | 17 | 2.4 |
1 Number of sites where median could be calculated (i.e. there was at least one sample result from that site within the time period of interest).
2 Health-related Maximum Allowable Value specified in DWSNZ 2005.
3 Trigger Value for stock drinking water specified in ANZECC 2000.
4 Percentage of monitoring sites at which median exceeds the water quality standard, relative to the total number of sites for which a median could be calculated for the parameter in question within the time period of interest.
5 Faecal coliforms used as a proxy for E. coli. Note that E. coli is the only parameter that is considered in DWSNZ 2005.
(Figure 1e) Lower graph. Percentiles by region for E. coli for period 1995-2008
| Council | n | Percentiles | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 21 | 9.2E-06 | 3.8E-04 | 1.5E-02 | 2.0E+00 | 1.5E+02 |
| Bay of Plenty | 20 | 5.0E-02 | 6.6E-01 | 1.0E+00 | 1.5E+00 | 8.1E+00 |
| Canterbury | 272 | 4.7E-03 | 4.6E-02 | 7.1E-01 | 2.7E+00 | 2.1E+01 |
| Gisborne | 0 | |||||
| Hawkes Bay | 35 | 1.7E-16 | 1.5E-12 | 5.7E-07 | 5.0E-01 | 8.1E+00 |
| Manawatu-Wanganui | 0 | |||||
| Marlborough | 9 | 9.5E-02 | 1.3E-01 | 5.5E-01 | 1.0E+00 | 6.0E+00 |
| Northland | 40 | 2.8E-13 | 1.4E-07 | 3.1E-01 | 1.1E+00 | 1.0E+01 |
| Otago | 62 | 7.0E-06 | 3.8E-04 | 1.9E-02 | 2.0E+00 | 2.1E+01 |
| Southland | 43 | 1.0E-03 | 4.6E-03 | 5.7E-02 | 1.0E+00 | 7.2E+00 |
| Taranaki | 67 | 1.9E-01 | 1.0E+00 | 5.0E+00 | 1.6E+01 | 1.6E+02 |
| Tasman | 0 | |||||
| Waikato | 64 | 1.8E-04 | 2.4E-03 | 4.9E-02 | 1.1E+00 | 1.2E+01 |
| Wellington | 60 | 5.3E-02 | 5.6E-01 | 1.5E+00 | 5.5E+00 | 2.5E+01 |
| West Coast | 8 | 1.2E-01 | 1.5E-01 | 4.8E-01 | 7.9E-01 | 3.6E+00 |
| All | 701 | 1.0E-08 | 1.0E-06 | 5.0E-04 | 1.0E+00 | 2.2E+01 |
(Figure 1f) Upper graph. Total number of monitoring sites (n) at which site-specific trend tests for E.coli could be performed for the time period 1995 to 2008 (i.e. the parameter had been measured at least three times between 1995 and 2008).
| Region | n | INCR | DECR | N | %INCR | %DECR | %N |
|---|---|---|---|---|---|---|---|
| Auckland | 7.0 | 0.0 | 0.0 | 7.0 | 0.0 | 0.0 | 100.0 |
| Bay of Plenty | 12.0 | 0.0 | 0.0 | 12.0 | 0.0 | 0.0 | 100.0 |
| Canterbury | 152.0 | 2.0 | 2.0 | 148.0 | 1.3 | 1.3 | 97.4 |
| Hawke's Bay | 12.0 | 0.0 | 0.0 | 12.0 | 0.0 | 0.0 | 100.0 |
| Manawatu | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Marlborough | 3.0 | 0.0 | 0.0 | 3.0 | 0.0 | 0.0 | 100.0 |
| Northland | 31.0 | 0.0 | 1.0 | 30.0 | 0.0 | 3.2 | 96.8 |
| Otago | 29.0 | 0.0 | 1.0 | 28.0 | 0.0 | 3.4 | 96.6 |
| Southland | 30.0 | 0.0 | 0.0 | 30.0 | 0.0 | 0.0 | 100.0 |
| Taranaki | 54.0 | 0.0 | 0.0 | 54.0 | 0.0 | 0.0 | 100.0 |
| Tasman | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Waikato | 20.0 | 0.0 | 0.0 | 20.0 | 0.0 | 0.0 | 100.0 |
| Wellington | 21.0 | 1.0 | 0.0 | 20.0 | 4.8 | 0.0 | 95.2 |
| West Coast | 8.0 | 0.0 | 0.0 | 8.0 | 0.0 | 0.0 | 100.0 |
(Figure 1f) Lower graph. Percentiles by region for trends in E.coli for period 1995-2008
| Council | n | Percentiles (mg/L) | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 7 | |||||
| Bay of Plenty | 12 | |||||
| Canterbury | 152 | -1.341 | -0.563 | 0.043 | 0.684 | 1.548 |
| Gisborne | 0 | |||||
| Hawkes Bay | 12 | |||||
| Manawatu-Wanganui | 0 | |||||
| Marlborough | 3 | |||||
| Northland | 31 | -1.398 | -1.398 | -1.398 | -1.398 | -1.398 |
| Otago | 29 | -37.029 | -37.029 | -37.029 | -37.029 | -37.029 |
| Southland | 30 | |||||
| Taranaki | 54 | |||||
| Tasman | 0 | |||||
| Waikato | 20 | |||||
| Wellington | 21 | 4.161 | 4.161 | 4.161 | 4.161 | 4.161 |
| West Coast | 8 | |||||
| All | 367 | -26.381 | -1.467 | -0.238 | 1.044 | 3.442 |
(Figure 1g) Upper graph. Percentage of New Zealand monitoring sites at which median concentrations calculated for the entire period from 1995 to 2008 exceed water quality guidelines for iron.
| Council | n1 | DWSNZ | |
|---|---|---|---|
| GV2 = 0.2 mg/L | |||
| # Sites Exceeding | % Sites Exceeding3 | ||
| Auckland | 23 | 6 | 26.1 |
| Bay of Plenty | 54 | 26 | 48.1 |
| Canterbury | 268 | 21 | 7.8 |
| Gisborne | 0 | ||
| Hawkes Bay | 45 | 17 | 37.8 |
| Manawatu-Wanganui | 27 | 14 | 51.9 |
| Marlborough | 24 | 3 | 12.5 |
| Northland | 39 | 14 | 35.9 |
| Otago | 80 | 14 | 17.5 |
| Southland | 39 | 4 | 10.3 |
| Taranaki | 7 | 1 | 14.3 |
| Tasman | 16 | 4 | 25.0 |
| Waikato | 110 | 12 | 10.9 |
| Wellington | 62 | 29 | 46.8 |
| West Coast | 8 | 1 | 12.5 |
| All | 802 | 171 | 21.3 |
1 Number of sites where median could be calculated (i.e. there was at least one sample result from that site within the time period of interest).
2 Aesthetic Guideline Value specified DWSNZ 2005
3 Percentage of monitoring sites at which median exceeds the water quality standard, relative to the total number of sites for which a median could be calculated for the parameter in question within the time period of interest.
(Figure 1g) Lower graph. Percentiles by region for iron for period 1995-2008
| Council | n | Percentiles (mg/L) | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 23 | 0.000 | 0.005 | 0.014 | 0.185 | 4.679 |
| Bay of Plenty | 54 | 0.001 | 0.016 | 0.102 | 1.621 | 9.207 |
| Canterbury | 268 | 0.004 | 0.019 | 0.040 | 0.065 | 0.235 |
| Gisborne | 0 | |||||
| Hawkes Bay | 45 | 0.001 | 0.020 | 0.160 | 0.795 | 8.928 |
| Manawatu-Wanganui | 27 | 0.045 | 0.070 | 0.360 | 2.300 | 30.500 |
| Marlborough | 24 | 0.001 | 0.007 | 0.012 | 0.023 | 0.474 |
| Northland | 39 | 0.000 | 0.004 | 0.050 | 0.975 | 9.744 |
| Otago | 80 | 0.000 | 0.005 | 0.019 | 0.066 | 1.500 |
| Southland | 39 | 0.001 | 0.003 | 0.004 | 0.014 | 6.140 |
| Taranaki | 7 | 0.001 | 0.016 | 0.030 | 0.105 | 2.028 |
| Tasman | 16 | 0.000 | 0.001 | 0.009 | 0.206 | 2.575 |
| Waikato | 110 | 0.000 | 0.000 | 0.000 | 0.019 | 0.719 |
| Wellington | 62 | 0.000 | 0.023 | 0.130 | 2.164 | 7.955 |
| West Coast | 8 | 0.005 | 0.009 | 0.039 | 0.101 | 0.226 |
| All | 802 | 0.000 | 0.010 | 0.030 | 0.120 | 4.480 |
(Figure 1h) Upper graph. Total number of monitoring sites (n) at which site-specific trend tests for iron could be performed for the time period 1995 to 2008 (i.e. the parameter had been measured at least three times between 1995 and 2008).
| Region | n | INCR | DECR | N | %INCR | %DECR | %N |
|---|---|---|---|---|---|---|---|
| Auckland | 23.0 | 9.0 | 0.0 | 14.0 | 39.1 | 0.0 | 60.9 |
| Bay of Plenty | 44.0 | 7.0 | 1.0 | 36.0 | 15.9 | 2.3 | 81.8 |
| Canterbury | 224.0 | 2.0 | 8.0 | 214.0 | 0.9 | 3.6 | 95.5 |
| Hawke's Bay | 45.0 | 2.0 | 21.0 | 22.0 | 4.4 | 46.7 | 48.9 |
| Manawatu | 26.0 | 1.0 | 9.0 | 16.0 | 3.8 | 34.6 | 61.5 |
| Marlborough | 21.0 | 0.0 | 2.0 | 19.0 | 0.0 | 9.5 | 90.5 |
| Northland | 33.0 | 0.0 | 2.0 | 31.0 | 0.0 | 6.1 | 93.9 |
| Otago | 58.0 | 1.0 | 0.0 | 57.0 | 1.7 | 0.0 | 98.3 |
| Southland | 35.0 | 5.0 | 4.0 | 26.0 | 14.3 | 11.4 | 74.3 |
| Taranaki | 7.0 | 0.0 | 1.0 | 6.0 | 0.0 | 14.3 | 85.7 |
| Tasman | 15.0 | 1.0 | 2.0 | 12.0 | 6.7 | 13.3 | 80.0 |
| Waikato | 23.0 | 1.0 | 2.0 | 20.0 | 4.3 | 8.7 | 87.0 |
| Wellington | 46.0 | 0.0 | 8.0 | 38.0 | 0.0 | 17.4 | 82.6 |
| West Coast | 7.0 | 0.0 | 1.0 | 6.0 | 0.0 | 14.3 | 85.7 |
(Figure 1h) Lower graph. Percentiles by region for trends in iron for period 1995-2008
| Council | n | Percentiles (mg/L) | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 23 | 0.001 | 0.003 | 0.052 | 0.119 | 0.160 |
| Bay of Plenty | 44 | 0.001 | 0.025 | 0.046 | 0.398 | 0.558 |
| Canterbury | 224 | -0.149 | -0.025 | -0.013 | -0.009 | 0.057 |
| Gisborne | 0 | |||||
| Hawkes Bay | 45 | -0.109 | -0.049 | -0.008 | -0.003 | 0.193 |
| Manawatu-Wanganui | 26 | -0.452 | -0.056 | -0.025 | -0.008 | 0.024 |
| Marlborough | 21 | -0.003 | -0.003 | -0.003 | -0.003 | -0.003 |
| Northland | 33 | -0.010 | -0.008 | -0.006 | -0.004 | -0.002 |
| Otago | 58 | 0.009 | 0.009 | 0.009 | 0.009 | 0.009 |
| Southland | 35 | -0.251 | -0.007 | 0.001 | 0.002 | 0.002 |
| Taranaki | 7 | -0.003 | -0.003 | -0.003 | -0.003 | -0.003 |
| Tasman | 15 | -0.083 | -0.049 | -0.006 | 0.215 | 0.393 |
| Waikato | 23 | -0.200 | -0.136 | -0.046 | -0.021 | -0.001 |
| Wellington | 46 | -0.129 | -0.025 | -0.011 | -0.004 | -0.002 |
| West Coast | 7 | -0.060 | -0.060 | -0.060 | -0.060 | -0.060 |
| All | 597 | -0.212 | -0.024 | -0.005 | 0.003 | 0.389 |
(Figure 1i) Upper graph. Percentage of New Zealand monitoring sites at which median concentrations calculated for the entire period from 1995 to 2008 exceed water quality guidelines for manganese.
| Council | n1 | DWSNZ | DWSNZ | ANZECC | |||
|---|---|---|---|---|---|---|---|
| GV2 = 0.04 mg/L | MAV3 = 0.4 mg/L | TV4 = 1.9 mg/L | |||||
| # Sites Exceeding | % Sites Exceeding5 | # Sites Exceeding | % Sites Exceeding5 | # Sites Exceeding | % Sites Exceeding5 | ||
| Auckland | 24 | 8 | 33.3 | 0 | 0.0 | 0 | 0.0 |
| Bay of Plenty | 54 | 26 | 48.1 | 13 | 24.1 | 4 | 7.4 |
| Canterbury | 268 | 29 | 10.8 | 8 | 3.0 | 2 | 0.7 |
| Gisborne | 0 | ||||||
| Hawkes Bay | 45 | 24 | 53.3 | 8 | 17.8 | 0 | 0.0 |
| Manawatu-Wanganui | 27 | 20 | 74.1 | 11 | 40.7 | 1 | 3.7 |
| Marlborough | 24 | 5 | 20.8 | 0 | 0.0 | 0 | 0.0 |
| Northland | 39 | 16 | 41.0 | 6 | 15.4 | 1 | 2.6 |
| Otago | 61 | 18 | 29.5 | 5 | 8.2 | 1 | 1.6 |
| Southland | 39 | 5 | 12.8 | 2 | 5.1 | 0 | 0.0 |
| Taranaki | 4 | 3 | 75.0 | 3 | 75.0 | 0 | 0.0 |
| Tasman | 16 | 3 | 18.8 | 1 | 6.3 | 1 | 6.3 |
| Waikato | 113 | 19 | 16.8 | 3 | 2.7 | 1 | 0.9 |
| Wellington | 62 | 29 | 46.8 | 15 | 24.2 | 0 | 0.0 |
| West Coast | 8 | 1 | 12.5 | 0 | 0.0 | 0 | 0.0 |
| All | 784 | 211 | 26.9 | 78 | 9.9 | 11 | 1.4 |
1 Number of sites where median could be calculated (i.e. there was at least one sample result from that site within the time period of interest).
2 Aesthetic Guideline Value specified in DWSNZ 2005.
3 Health-related Maximum Allowable Value specified in DWSNZ 2005.
4 Trigger Value for ecosystem protection (95% level) specified in ANZECC 2000.
5 Percentage of monitoring sites at which median exceeds the water quality standard, relative to the total number of sites for which a median could be calculated for the parameter in question within the time period of interest.
(Figure 1i) Lower graph. Percentiles by region for manganese for period 1995-2008
| Council | n | Percentiles (mg/L) | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 24 | 0.000 | 0.002 | 0.018 | 0.058 | 0.169 |
| Bay of Plenty | 54 | 0.000 | 0.002 | 0.027 | 0.374 | 3.751 |
| Canterbury | 268 | 0.005 | 0.008 | 0.010 | 0.017 | 0.164 |
| Gisborne | 0 | |||||
| Hawkes Bay | 45 | 0.000 | 0.006 | 0.046 | 0.210 | 0.616 |
| Manawatu-Wanganui | 27 | 0.001 | 0.032 | 0.270 | 0.725 | 1.185 |
| Marlborough | 24 | 0.000 | 0.000 | 0.002 | 0.016 | 0.077 |
| Northland | 39 | 0.000 | 0.002 | 0.025 | 0.215 | 1.439 |
| Otago | 61 | 0.000 | 0.001 | 0.010 | 0.058 | 0.490 |
| Southland | 39 | 0.000 | 0.000 | 0.001 | 0.004 | 0.366 |
| Taranaki | 4 | 0.002 | 0.006 | 0.009 | 0.257 | 0.661 |
| Tasman | 16 | 0.000 | 0.000 | 0.001 | 0.017 | 0.890 |
| Waikato | 113 | 0.000 | 0.001 | 0.002 | 0.009 | 0.226 |
| Wellington | 62 | 0.000 | 0.000 | 0.019 | 0.350 | 1.123 |
| West Coast | 8 | 0.000 | 0.001 | 0.007 | 0.030 | 0.112 |
| All | 784 | 0.000 | 0.000 | 0.010 | 0.050 | 0.850 |
(Figure 1j) Upper graph. Total number of monitoring sites (n) at which site-specific trend tests for manganese could be performed for the time period 1995 to 2008 (i.e. the parameter had been measured at least three times between 1995 and 2008).
| Region | n | INCR | DECR | N | %INCR | %DECR | %N |
|---|---|---|---|---|---|---|---|
| Auckland | 24.0 | 8.0 | 2.0 | 14.0 | 33.3 | 8.3 | 58.3 |
| Bay of Plenty | 50.0 | 3.0 | 4.0 | 43.0 | 6.0 | 8.0 | 86.0 |
| Canterbury | 118.0 | 0.0 | 3.0 | 115.0 | 0.0 | 2.5 | 97.5 |
| Hawke's Bay | 44.0 | 6.0 | 12.0 | 26.0 | 13.6 | 27.3 | 59.1 |
| Manawatu | 21.0 | 2.0 | 7.0 | 12.0 | 9.5 | 33.3 | 57.1 |
| Marlborough | 19.0 | 5.0 | 1.0 | 13.0 | 26.3 | 5.3 | 68.4 |
| Northland | 39.0 | 3.0 | 6.0 | 30.0 | 7.7 | 15.4 | 76.9 |
| Otago | 29.0 | 0.0 | 0.0 | 29.0 | 0.0 | 0.0 | 100.0 |
| Southland | 29.0 | 2.0 | 5.0 | 22.0 | 6.9 | 17.2 | 75.9 |
| Taranaki | 6.0 | 0.0 | 3.0 | 3.0 | 0.0 | 50.0 | 50.0 |
| Tasman | 12.0 | 2.0 | 1.0 | 9.0 | 16.7 | 8.3 | 75.0 |
| Waikato | 85.0 | 0.0 | 1.0 | 84.0 | 0.0 | 1.2 | 98.8 |
| Wellington | 38.0 | 3.0 | 5.0 | 30.0 | 7.9 | 13.2 | 78.9 |
| West Coast | 7.0 | 2.0 | 0.0 | 5.0 | 28.6 | 0.0 | 71.4 |
(Figure 1j) Lower graph. Percentiles by region for trends in manganese for period 1995-2008
| Council | n | Percentiles (mg/L) | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 24.000 | 0.000 | 0.000 | 0.001 | 0.001 | 0.005 |
| Bay of Plenty | 50.000 | -0.015 | -0.005 | -0.003 | 0.000 | 0.010 |
| Canterbury | 118.000 | -0.200 | -0.123 | -0.028 | -0.014 | -0.003 |
| Gisborne | 0.000 | |||||
| Hawkes Bay | 44.000 | -0.003 | -0.001 | 0.000 | 0.002 | 0.014 |
| Manawatu-Wanganui | 21.000 | -0.048 | -0.036 | -0.005 | -0.001 | 0.018 |
| Marlborough | 19.000 | 0.000 | 0.000 | 0.000 | 0.000 | 0.001 |
| Northland | 39.000 | -0.164 | -0.023 | -0.001 | 0.000 | 0.002 |
| Otago | 29.000 | |||||
| Southland | 29.000 | -0.012 | -0.007 | -0.001 | 0.001 | 0.005 |
| Taranaki | 6.000 | -0.024 | -0.017 | -0.008 | -0.004 | -0.001 |
| Tasman | 12.000 | -0.001 | 0.000 | 0.002 | 0.012 | 0.021 |
| Waikato | 85.000 | -0.001 | -0.001 | -0.001 | -0.001 | -0.001 |
| Wellington | 38.000 | -0.042 | -0.024 | 0.000 | 0.001 | 0.006 |
| West Coast | 7.000 | 0.004 | 0.017 | 0.034 | 0.050 | 0.063 |
| All | 523.000 | -0.047 | -0.004 | 0.000 | 0.001 | 0.019 |
(Figure 1k) Percentiles by region for conductivity for period 1995-2008
| Council | n | Percentiles (mg/L) | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 23 | 185.415 | 256.075 | 316.000 | 452.375 | 701.500 |
| Bay of Plenty | 54 | 88.405 | 123.200 | 207.750 | 490.250 | 27500.000 |
| Canterbury | 278 | 89.400 | 128.000 | 174.000 | 221.000 | 401.000 |
| Gisborne | 0 | |||||
| Hawkes Bay | 44 | 115.225 | 161.200 | 231.950 | 419.613 | 2617.000 |
| Manawatu-Wanganui | 27 | 166.650 | 287.250 | 464.000 | 577.000 | 6135.000 |
| Marlborough | 22 | 68.125 | 116.913 | 150.725 | 212.813 | 427.175 |
| Northland | 40 | 146.150 | 398.750 | 519.750 | 660.250 | 4392.000 |
| Otago | 99 | 91.550 | 160.575 | 221.000 | 483.825 | 1490.000 |
| Southland | 47 | 115.050 | 149.750 | 210.000 | 265.000 | 430.450 |
| Taranaki | 71 | 96.250 | 148.000 | 253.000 | 334.250 | 621.250 |
| Tasman | 16 | 142.238 | 205.775 | 219.500 | 299.150 | 481.750 |
| Waikato | 115 | 75.700 | 128.250 | 197.000 | 260.250 | 393.200 |
| Wellington | 71 | 90.250 | 138.625 | 200.000 | 319.000 | 700.000 |
| West Coast | 8 | 64.800 | 74.500 | 84.500 | 89.625 | 92.475 |
| All | 915 | 89.000 | 141.500 | 204.000 | 319.500 | 807.000 |
(Figure 1l) Upper graph. Total number of monitoring sites (n) at which site-specific trend tests for electrical conductivity could be performed for the time period 1995 to 2008 (i.e. the parameter had been measured at least three times between 1995 and 2008).
| Region | n | INCR | DECR | N | %INCR | %DECR | %N |
|---|---|---|---|---|---|---|---|
| Auckland | 23.0 | 3.0 | 0.0 | 20.0 | 13.0 | 0.0 | 87.0 |
| Bay of Plenty | 54.0 | 2.0 | 9.0 | 43.0 | 3.7 | 16.7 | 79.6 |
| Canterbury | 277.0 | 78.0 | 7.0 | 192.0 | 28.2 | 2.5 | 69.3 |
| Hawke's Bay | 44.0 | 9.0 | 12.0 | 23.0 | 20.5 | 27.3 | 52.3 |
| Manawatu | 27.0 | 2.0 | 8.0 | 17.0 | 7.4 | 29.6 | 63.0 |
| Marlborough | 22.0 | 3.0 | 1.0 | 18.0 | 13.6 | 4.5 | 81.8 |
| Northland | 40.0 | 9.0 | 5.0 | 26.0 | 22.5 | 12.5 | 65.0 |
| Otago | 99.0 | 1.0 | 27.0 | 71.0 | 1.0 | 27.3 | 71.7 |
| Southland | 40.0 | 15.0 | 5.0 | 20.0 | 37.5 | 12.5 | 50.0 |
| Taranaki | 71.0 | 6.0 | 15.0 | 50.0 | 8.5 | 21.1 | 70.4 |
| Tasman | 16.0 | 8.0 | 1.0 | 7.0 | 50.0 | 6.3 | 43.8 |
| Waikato | 114.0 | 23.0 | 11.0 | 80.0 | 20.2 | 9.6 | 70.2 |
| Wellington | 71.0 | 7.0 | 21.0 | 43.0 | 9.9 | 29.6 | 60.6 |
| West Coast | 8.0 | 1.0 | 0.0 | 7.0 | 12.5 | 0.0 | 87.5 |
(Figure 1l) Lower graph. Percentiles by region for trends in electrical conductivity for period 1995-2008
| Council | n | Percentiles | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| Auckland | 23 | 7.684 | 8.332 | 9.141 | 11.961 | 14.217 |
| Bay of Plenty | 54 | -19.406 | -11.507 | -2.893 | -1.198 | 54.114 |
| Canterbury | 227 | -5.014 | 2.674 | 6.309 | 10.034 | 20.172 |
| Gisborne | 0 | |||||
| Hawkes Bay | 44 | -24.154 | -2.019 | -0.636 | 3.556 | 4.888 |
| Manawatu-Wanganui | 27 | -42.946 | -5.534 | -1.998 | -1.689 | 2.962 |
| Marlborough | 22 | -3.060 | 0.533 | 6.336 | 11.475 | 13.476 |
| Northland | 40 | -19.030 | -9.446 | 7.136 | 13.269 | 68.963 |
| Otago | 99 | -24.596 | -9.700 | -7.095 | -4.527 | -1.920 |
| Southland | 40 | -1.795 | 0.691 | 2.629 | 4.098 | 12.037 |
| Taranaki | 71 | -18.841 | -9.379 | -3.305 | 0.000 | 9.471 |
| Tasman | 16 | -2.023 | 2.548 | 4.019 | 9.610 | 11.602 |
| Waikato | 114 | -8.650 | -1.809 | 2.133 | 6.427 | 11.243 |
| Wellington | 71 | -15.152 | -6.673 | -3.905 | -0.128 | 9.631 |
| West Coast | 8 | 9.044 | 9.044 | 9.044 | 9.044 | 9.044 |
| All | 906 | -16.161 | -4.439 | 2.014 | 6.628 | 17.376 |
