Figure 5. Year-by-year changes in regional percentiles for E. coli in groundwater, based on site-specific median values. Faecal colifom concentrations (blue) or total coliform concentrations (green) used where E. coli data were not available. All Y axis scales in cfu/100 ml. Numbers above X axes show the number of sites at which median values could be calculated for the region and calendar year of interest. Horizontal lines on each graph represent the health-related Maximum Acceptable Value (1 cfu/100 ml) specified in the DWSNZ and the Trigger Value for livestock consumption (100 cfu/100 ml) defined in the ANZECC guidelines.
Read a description of this figure
(Figure 5a) Auckland Region calculated percentiles and maximum values for E. coli in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 0 | ||||||
| 1996 | 0 | ||||||
| 1997 | 0 | ||||||
| 1998 | 0 | ||||||
| 1999 | 0 | ||||||
| 2000 | 0 | ||||||
| 2001 | 0 | ||||||
| 2002 | 0 | ||||||
| 2003 | 0 | ||||||
| 2004 | 0 | ||||||
| 2005 | 18 | 2.3E-09 | 3.0E-07 | 0.0002 | 0.06 | 43.80 | 190 |
| 2006 | 21 | 5.0E-13 | 6.1E-10 | 0.0000 | 0.03 | 150.00 | 300 |
| 2007 | 22 | 9.0E-08 | 8.2E-06 | 0.0021 | 1.55 | 124.53 | 135 |
| 2008 | 23 | 2.9E-06 | 1.3E-04 | 0.0127 | 1.49 | 37.60 | 555 |
| Change in Percentile Value Over Time2 | - | - | - | - | - | - | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5b) Bay of Plenty Region calculated percentiles and maximum values for faecal coliforms in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 9 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 |
| 1996 | 12 | 6.1E-08 | 2.8E-06 | 4.5E-04 | 0.3 | 10.1 | 20.0 |
| 1997 | 12 | 0.1 | 0.2 | 0.4 | 1.0 | 1.5 | 2.0 |
| 1998 | 13 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| 1999 | 0 | ||||||
| 2000 | 1 | <1 | <1 | <1 | <1 | <1 | <1 |
| 2001 | 0 | ||||||
| 2002 | 9 | 6.0 | 6.0 | 6.0 | 6.0 | 6.0 | 6.0 |
| 2003 | 5 | 13.0 | 13.0 | 13.0 | 13.0 | 13.0 | 13.0 |
| 2004 | 10 | 3.6E-02 | 0.3 | 1.0 | 18.3 | 67.6 | 91.0 |
| 2005 | 10 | 1.2E-07 | 6.1E-06 | 7.8E-04 | 0.8 | 23.5 | 41.0 |
| 2006 | 8 | <1 | <1 | <1 | <1 | <1 | <1 |
| 2007 | 12 | 1.8E-07 | 8.0E-06 | 1.2E-03 | 0.2 | 19.8 | 33.0 |
| 2008 | 6 | 2.0 | 2.0 | 2.0 | 2.0 | 2.0 | 2.0 |
| Change in Percentile Value Over Time2 | - | - | - | - | - | - | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5c) Canterbury Region calculated percentiles and maximum values for E. coli in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 0 | ||||||
| 1996 | 0 | ||||||
| 1997 | 0 | ||||||
| 1998 | 0 | ||||||
| 1999 | 227 | 0.000 | 0.000 | 0.003 | 0.59 | 5.0 | 670 |
| 2000 | 236 | 0.049 | 0.267 | 1.000 | 3.28 | 25.4 | 260 |
| 2001 | 245 | 0.004 | 0.036 | 0.529 | 1.66 | 17.7 | 2400 |
| 2002 | 247 | 0.005 | 0.055 | 0.783 | 3.60 | 45.6 | 2400 |
| 2003 | 243 | 0.517 | 1.731 | 3.421 | 8.23 | 25.5 | 2400 |
| 2004 | 241 | 0.001 | 0.010 | 0.204 | 1.50 | 15.6 | 1300 |
| 2005 | 255 | 0.009 | 0.081 | 1.000 | 3.25 | 38.4 | 2400 |
| 2006 | 254 | 0.005 | 0.056 | 0.883 | 2.21 | 12.0 | 501 |
| 2007 | 275 | 0.000 | 0.004 | 0.227 | 1.48 | 12.1 | 1700 |
| 2008 | 284 | 0.000 | 0.009 | 0.637 | 3.97 | 23.9 | 2400 |
| Change in Percentile Value Over Time2 | - | - | - | - | - | - | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5d) Data not available
(Figure 5e) Hawkes Bay Region calculated percentiles and maximum values for E. coli (for years 2005-2008) or faecal coliforms (for years 1997-2004) in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 0 | ||||||
| 1996 | 0 | ||||||
| 1997 | 33 | 0.001 | 0.001 | 0.001 | 0.01 | 4.0 | 16 |
| 1998 | 34 | 0.001 | 0.001 | 0.000 | 0.06 | 4.0 | 15 |
| 1999 | 33 | 0.001 | 0.001 | 0.154 | 1.88 | 95.4 | 150 |
| 2000 | 33 | 0.001 | 0.003 | 0.038 | 1.00 | 6.8 | 31 |
| 2001 | 34 | 0.001 | 0.001 | 0.001 | 0.01 | 2.5 | 147 |
| 2002 | 33 | 0.001 | 0.001 | 0.001 | 0.01 | 4.0 | 96 |
| 2003 | 34 | 0.001 | 0.001 | 0.131 | 1.44 | 15.0 | 250 |
| 2004 | 33 | 0.001 | 0.001 | 0.001 | 0.02 | 4.0 | 34 |
| 2005 | 33 | 1.867 | 1.946 | 2.042 | 2.19 | 2.3 | 22 |
| 2006 | 34 | 0.016 | 0.040 | 0.131 | 0.43 | 1.0 | 2 |
| 2007 | 35 | 0.000 | 0.000 | 0.000 | 0.00 | 61.5 | 1300 |
| 2008 | 34 | 0.000 | 0.002 | 0.029 | 0.38 | 1.2 | 22 |
| Change in Percentile Value Over Time2 | - | - | - | - | - | - | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5f) Data not available
(Figure 5g) Marlborough Region calculated percentiles and maximum values for E. coli in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 0 | ||||||
| 1996 | 0 | ||||||
| 1997 | 0 | ||||||
| 1998 | 0 | 8.760 | 8.760 | 8.760 | 8.76 | 8.8 | 9 |
| 1999 | 0 | ||||||
| 2000 | 0 | ||||||
| 2001 | 2 | 2.000 | 2.000 | 2.000 | 2.00 | 2.0 | 2 |
| 2002 | 0 | ||||||
| 2003 | 0 | ||||||
| 2004 | 0 | ||||||
| 2005 | 5 | 1.000 | 1.000 | 1.000 | 1.00 | 1.0 | 1 |
| 2006 | 6 | <1 | <1 | <1 | <1 | <1 | <1 |
| 2007 | 0 | ||||||
| 2008 | 6 | 0.000 | 0.001 | 0.010 | 0.12 | 3.6 | 9 |
| Change in Percentile Value Over Time2 | -0.42 | -0.42 | -0.42 | -0.40 | -0.40 | -0.28 | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5h) Northland Region calculated percentiles and maximum values for E. coli in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 0 | ||||||
| 1996 | 0 | ||||||
| 1997 | 0 | ||||||
| 1998 | 0 | ||||||
| 1999 | 0 | ||||||
| 2000 | 0 | ||||||
| 2001 | 3 | 4.050 | 8.250 | 16.00 | 100.3 | 288.1 | 335 |
| 2002 | 7 | 7.8E-10 | 2.8E-08 | 0.03 | 0.8 | 340.6 | 616 |
| 2003 | 19 | 3.2E-05 | 4.5E-04 | 0.03 | 1.8 | 811.3 | 2000 |
| 2004 | 27 | 0.006 | 0.018 | 0.55 | 6.5 | 22.4 | 345 |
| 2005 | 27 | 1.5E-04 | 0.002 | 0.56 | 3.0 | 29.3 | 179 |
| 2006 | 29 | 0.026 | 0.084 | 1.00 | 2.3 | 16.5 | 44 |
| 2007 | 32 | 0.012 | 0.076 | 1.00 | 3.5 | 313.8 | 1210 |
| 2008 | 32 | 0.003 | 0.019 | 1.00 | 3.0 | 62.9 | 2419 |
| Change in Percentile Value Over Time2 | - | - | - | - | - | - | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5i) Otago Region calculated percentiles and maximum values for E. coli in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 0 | ||||||
| 1996 | 0 | ||||||
| 1997 | 0 | ||||||
| 1998 | 2 | 2.000 | 2.000 | 2.00 | 2.00 | 2.0 | 2 |
| 1999 | 5 | 0.679 | 2.000 | 3.00 | 13.25 | 845.4 | 1200 |
| 2000 | 17 | 0.002 | 0.020 | 1.00 | 25.50 | 156.8 | 330 |
| 2001 | 27 | 0.000 | 0.000 | 0.03 | 13.75 | 216.8 | 2414 |
| 2002 | 21 | 0.003 | 0.018 | 0.22 | 3.00 | 47.4 | 300 |
| 2003 | 27 | 0.000 | 0.000 | 0.00 | 0.77 | 15.8 | 870 |
| 2004 | 21 | 0.036 | 0.133 | 1.00 | 3.25 | 19.1 | 45 |
| 2005 | 21 | 0.000 | 0.002 | 0.03 | 1.50 | 19.4 | 190 |
| 2006 | 22 | 0.000 | 0.003 | 0.06 | 4.25 | 34.7 | 102 |
| 2007 | 28 | 0.005 | 0.028 | 0.19 | 1.62 | 12.0 | 16 |
| 2008 | 27 | 1.000 | 1.000 | 1.00 | 1.00 | 1.0 | 1 |
| Change in Percentile Value Over Time2 | - | - | - | - | - | -51 | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5j) Southland region percentiles and maximum values for E. coli in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 0 | ||||||
| 1996 | 0 | ||||||
| 1997 | 0 | ||||||
| 1998 | 0 | ||||||
| 1999 | 0 | ||||||
| 2000 | 0 | ||||||
| 2001 | 13 | 1.7E-06 | 4.6E-05 | 0.003 | 0.24 | 2.7 | 18 |
| 2002 | 15 | 1.3E-07 | 1.2E-05 | 0.004 | 1.03 | 20.7 | 650 |
| 2003 | 19 | 1.8E-05 | 3.8E-04 | 0.016 | 1.00 | 11.1 | 180 |
| 2004 | 16 | 1.3E-03 | 6.7E-03 | 0.074 | 1.00 | 2.8 | 11 |
| 2005 | 22 | 1.6E-03 | 1.5E-02 | 1.000 | 1.00 | 39.4 | 2400 |
| 2006 | 19 | 2.7E-04 | 2.5E-03 | 0.039 | 0.72 | 4.1 | 10 |
| 2007 | 21 | 5.5E-01 | 1.5E+00 | 2.276 | 3.50 | 5.0 | 14 |
| 2008 | 30 | 2.6E-03 | 2.2E-02 | 0.345 | 1.11 | 9.4 | 517 |
| Change in Percentile Value Over Time2 | 0.0004 | 0.004 | 0.058 | - | - | - | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5k) Taranaki Region calculated percentiles and maximum values for E. coli in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 0 | ||||||
| 1996 | 1 | <1 | <1 | <1 | <1 | <1 | <1 |
| 1997 | 3 | 0.34 | 1.51 | 2.5 | 24 | 75 | 88 |
| 1998 | 3 | 1.34 | 6.04 | 19.5 | 171 | 506 | 590 |
| 1999 | 0 | ||||||
| 2000 | 0 | ||||||
| 2001 | 0 | ||||||
| 2002 | 0 | ||||||
| 2003 | 0 | ||||||
| 2004 | 10 | 11.00 | 11.00 | 11.0 | 11 | 11 | 11 |
| 2005 | 0 | ||||||
| 2006 | 60 | 0.32 | 0.75 | 6.0 | 19 | 40 | 54 |
| 2007 | 59 | 0.00 | 0.02 | 1.0 | 38 | 423 | 515 |
| 2008 | 0 | ||||||
| Change in Percentile Value Over Time2 | - | - | - | - | - | - | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5l) Data not available
(Figure 5m) Waikato Region calculated percentiles and maximum values for E. coli in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 0 | ||||||
| 1996 | 0 | ||||||
| 1997 | 0 | ||||||
| 1998 | 13 | 0.014 | 0.069 | 0.50 | 5.00 | 29.8 | 34 |
| 1999 | 0 | ||||||
| 2000 | 0 | ||||||
| 2001 | 0 | ||||||
| 2002 | 0 | ||||||
| 2003 | 1 | <1 | <1 | <1 | <1 | <1 | <1 |
| 2004 | 43 | 1.4E-04 | 1.8E-03 | 0.04 | 1.00 | 11.7 | 32 |
| 2005 | 15 | 0.003 | 0.024 | 0.58 | 1.75 | 40.9 | 190 |
| 2006 | 4 | <1 | <1 | <1 | <1 | <1 | <1 |
| 2007 | 1 | 2.000 | 2.000 | 2.00 | 2.00 | 2.0 | 2 |
| 2008 | 42 | 4.9E-10 | 1.2E-07 | 0.00 | 0.11 | 15.8 | 1600 |
| Change in Percentile Value Over Time2 | - | - | - | - | - | - | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5n) Wellington Region calculated percentiles and maximum values for E. coli (for years 2004-2008) or total coliforms (for years 1995-2003) in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 3 | 1.3E+00 | 2.5E+00 | 4.0000 | 8.50 | 12.1 | 13 |
| 1996 | 4 | 1.0E+00 | 1.0E+00 | 33.0000 | 186.00 | 278.0 | 301 |
| 1997 | 3 | 3.1E+00 | 1.2E+01 | 19.5000 | 24.38 | 25.3 | 26 |
| 1998 | 9 | 1.0E+00 | 1.0E+00 | 5.0000 | 32.50 | 150.3 | 184 |
| 1999 | 12 | 7.3E-02 | 1.0E+00 | 2.0000 | 8.00 | 148.1 | 319 |
| 2000 | 11 | 1.0E+00 | 1.0E+00 | 3.0000 | 83.00 | 330.2 | 416 |
| 2001 | 9 | 1.5E+00 | 3.0E+00 | 8.0000 | 35.00 | 199.5 | 262 |
| 2002 | 14 | 3.4E-02 | 1.2E-01 | 1.0000 | 3.00 | 23.8 | 35 |
| 2003 | 42 | 2.0E-12 | 9.7E-10 | 0.0000 | 0.01 | 3.6 | 12 |
| 2004 | 52 | 2.9E-07 | 1.5E-05 | 0.0022 | 0.31 | 2.3 | 31 |
| 2005 | 59 | 2.1E-23 | 3.4E-18 | 0.0000 | 0.00 | 8.8 | 100 |
| 2006 | 58 | 1.4E-02 | 5.0E-02 | 0.2789 | 1.00 | 3.0 | 5 |
| 2007 | 42 | 7.8E-16 | 2.3E-12 | 0.0000 | 0.00 | 82.9 | 840 |
| 2008 | 38 | 5.0E-07 | 4.8E-05 | 0.0143 | 0.91 | 10.2 | 301 |
| Change in Percentile Value Over Time2 | -0.100 | -0.136 | -0.500 | -1.67 | - | - | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
(Figure 5o) West Coast Region calculated percentiles and maximum values for E. coli in groundwater (in cfu/100 ml), based on site-specific median values.
| Parameter | n1 | Percentile | Max | ||||
|---|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | |||
| 1995 | 0 | ||||||
| 1996 | 0 | ||||||
| 1997 | 0 | ||||||
| 1998 | 0 | ||||||
| 1999 | 0 | ||||||
| 2000 | 5 | 5.0 | 5.0 | 5.0 | 5 | 5 | 5 |
| 2001 | 7 | 5.0 | 5.0 | 5.0 | 5 | 5 | 5 |
| 2002 | 6 | 0.4 | 2.0 | 5.0 | 5 | 159 | 210 |
| 2003 | 7 | 3.0 | 3.3 | 5.0 | 5 | 5 | 5 |
| 2004 | 7 | 0.1 | 0.2 | 1.0 | 3 | 6 | 6 |
| 2005 | 8 | 4.1 | 4.8 | 5.0 | 5 | 5 | 5 |
| 2006 | 8 | 1.0 | 1.3 | 5.0 | 5 | 8 | 11 |
| 2007 | 8 | 0.0 | 0.0 | 0.3 | 1 | 15 | 23 |
| 2008 | 8 | 1.0 | 1.0 | 1.0 | 1 | 1 | 1 |
| Change in Percentile Value Over Time2 | - | -0.6 | - | - | - | - | |
1 Total number of sites for which a median value could be calculated (i.e. parameter had been measured at least once at the site in question within the calender year of interest).
2 Trend tests performed on calculated percentile values for the years 1995 to 2008. A null value (-) indicates that no significant trend was detected at the 95% confidence interval. Numbers are in units per year and indicate significant trends. Negative numbers indicate a decreasing trend.
