Figure 7. Year-by-year changes in regional percentiles for manganese (Mn) in groundwater. Total Mn concentrations (blue) used where dissolved Mn data were not available. All Y axis scales in mg/L. 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 aesthetic Guideline Value (0.04 mg/L) and the health-related Maximum Acceptable Value (0.4 mg/L) specified in the DWSNZ and the Trigger Value for ecosystem protection (1.9 mg/L) defined in the ANZECC guidelines.

Figure 7. Year-by-year changes in regional percentiles for manganese (Mn) in groundwater

Read a description of this figure

(Figure 7a) Auckland Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	0
1996	2	6.0E-02	6.0E-02	0.0600	0.06	0.06	0.1
1997	4	2.0E-03	7.6E-03	0.0300	0.12	0.27	0.3
1998	20	6.1E-04	2.0E-03	0.0315	0.09	0.22	0.3
1999	23	8.5E-04	2.8E-03	0.0180	0.06	0.20	0.3
2000	22	6.9E-04	1.8E-03	0.0208	0.08	0.19	0.2
2001	23	9.2E-04	2.0E-03	0.0225	0.06	0.16	0.2
2002	23	8.4E-04	2.0E-03	0.0225	0.06	0.14	0.2
2003	22	7.6E-04	2.3E-03	0.0114	0.06	0.17	0.2
2004	22	5.7E-04	2.6E-03	0.0221	0.06	0.15	0.2
2005	22	5.2E-04	2.8E-03	0.0257	0.07	0.18	0.2
2006	21	8.0E-04	3.6E-03	0.0200	0.06	0.18	0.2
2007	22	9.6E-04	4.5E-03	0.0233	0.07	0.17	0.2
2008	23	7.2E-04	6.0E-03	0.0250	0.06	0.16	0.2
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 7b) Bay of Plenty Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	5th	25th	50th	75th	95th	Max
Parameter	n¹	Percentile					Max
1995	0
1996	48	1.5E-04	0.001	0.055	0.25	2.05	9.2
1997	53	2.2E-04	0.001	0.030	0.31	3.24	15.4
1998	37	3.6E-05	0.001	0.030	0.44	1.71	12.7
1999	12	3.2E-03	0.010	0.030	0.16	0.53	0.5
2000	12	5.0E-04	0.002	0.028	0.21	0.50	0.5
2001	6	1.7E-03	0.007	0.027	0.18	0.45	0.5
2002	25	1.6E-04	0.001	0.017	0.22	1.59	5.2
2003	15	3.0E-03	0.004	0.029	0.49	1.48	2.9
2004	6	1.6E-03	0.005	0.054	0.18	0.41	0.5
2005	37	5.9E-04	0.003	0.011	0.28	1.03	4.3
2006	47	8.7E-04	0.003	0.017	0.38	2.34	9.6
2007	38	1.7E-04	0.001	0.008	0.27	0.98	3.4
2008	41	3.3E-04	0.001	0.011	0.28	1.11	8.8
Change in Percentile Value Over Time²		-	-	-0.002	-	-	-

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).

(Figure 7c) Canterbury Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	9	0.004	0.008	0.019	0.080	0.126	0.15
1996	4	0.030	0.030	0.030	0.030	0.030	0.03
1997	9	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01
1998	9	0.010	0.010	0.010	0.010	0.010	0.01
1999	3	0.004	0.004	0.004	0.004	0.004	0.00
2000	3	<0.005	<0.005	<0.005	<0.005	<0.005	<0.005
2001	3	0.006	0.006	0.006	0.006	0.006	0.01
2002	3	0.031	0.031	0.031	0.031	0.031	0.03
2003	256	0.000	0.000	0.008	0.035	0.314	3.40
2004	255	0.001	0.003	0.010	0.037	0.313	3.90
2005	273	0.000	0.000	0.009	0.043	0.345	3.40
2006	277	0.000	0.000	0.000	0.002	0.292	3.40
2007	276	0.000	0.000	0.000	0.002	0.180	2.80
2008	285	0.000	0.000	0.000	0.003	0.126	3.00
Change in Percentile Value Over Time²		-0.001	-0.001	-	-	-	-

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).

(Figure 7d) Data not available

(Figure 7e) Hawkes Bay Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	16	0.003	0.014	0.080	0.240	0.589	0.67
1996	6	0.007	0.038	0.060	0.270	0.507	0.53
1997	39	0.001	0.010	0.059	0.220	0.588	1.26
1998	43	0.002	0.008	0.059	0.238	0.595	1.30
1999	42	0.001	0.007	0.044	0.208	0.600	1.25
2000	40	0.001	0.006	0.050	0.241	0.576	1.30
2001	43	0.001	0.007	0.050	0.220	0.603	1.40
2002	38	0.002	0.009	0.056	0.189	0.831	1.23
2003	43	0.001	0.007	0.050	0.218	0.584	1.25
2004	41	0.002	0.007	0.056	0.275	0.579	1.33
2005	42	0.001	0.005	0.060	0.346	0.748	1.37
2006	43	0.001	0.004	0.053	0.373	0.662	1.45
2007	43	0.001	0.003	0.050	0.359	0.642	1.34
2008	43	0.001	0.007	0.056	0.335	0.623	1.40
Change in Percentile Value Over Time²	-	0.000	-0.001	-	-	-	0.02

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).

(Figure 7f) Manawatu-Wanganui Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	2	0.252	0.300	0.590	1.15	1.83	2.00
1996	2	0.023	0.049	0.388	0.81	1.76	2.00
1997	2	0.025	0.053	0.358	0.94	1.70	2.00
1998	4	0.011	0.050	0.340	0.93	2.67	3.15
1999	4	0.008	0.051	0.215	0.74	1.18	3.05
2000	3	0.007	0.050	0.270	0.84	1.17	3.05
2001	3	0.007	0.074	0.260	0.82	1.27	2.90
2002	5	0.038	0.158	0.695	0.93	1.40	3.05
2003	3	0.061	0.165	0.710	0.92	1.72	3.00
2004	3	0.052	0.392	0.739	1.00	1.91	2.70
2005	2	0.253	0.607	0.760	0.99	2.20	2.79
2006	16	0.021	0.048	0.167	0.32	1.04	2.16
2007	2	0.586	0.685	0.888	0.98	2.14	2.52
2008	2	0.011	0.027	0.046	0.20	0.33	0.36
Change in Percentile Value Over Time²		-	-	-	-	-	-

(Figure 7g) Marlborough Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	0
1996	0
1997	1	0.060	0.060	0.060	0.060	0.060	0.06
1998	4	0.015	0.015	0.015	0.015	0.015	0.02
1999	4	0.000	0.002	0.013	0.046	0.171	0.21
2000	3	0.016	0.024	0.043	0.099	0.200	0.23
2001	5	0.002	0.006	0.014	0.072	0.171	0.21
2002	4	0.004	0.009	0.036	0.073	0.155	0.18
2003	4	0.001	0.002	0.028	0.077	0.172	0.20
2004	6	0.002	0.004	0.030	0.067	0.162	0.21
2005	13	0.000	0.001	0.003	0.041	0.105	0.25
2006	6	0.002	0.005	0.029	0.066	0.148	0.19
2007	6	0.001	0.003	0.034	0.073	0.134	0.17
2008	6	0.009	0.015	0.043	0.072	0.164	0.21
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).

(Figure 7h) Northland Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	0
1996	0
1997	1	0.060	0.060	0.060	0.060	0.060	0.06
1998	4	0.015	0.015	0.015	0.015	0.015	0.02
1999	4	0.000	0.002	0.013	0.046	0.171	0.21
2000	3	0.016	0.024	0.043	0.099	0.200	0.23
2001	5	0.002	0.006	0.014	0.072	0.171	0.21
2002	4	0.004	0.009	0.036	0.073	0.155	0.18
2003	4	0.001	0.002	0.028	0.077	0.172	0.20
2004	6	0.002	0.004	0.030	0.067	0.162	0.21
2005	13	0.000	0.001	0.003	0.041	0.105	0.25
2006	6	0.002	0.005	0.029	0.066	0.148	0.19
2007	6	0.001	0.003	0.034	0.073	0.134	0.17
2008	6	0.009	0.015	0.043	0.072	0.164	0.21
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).

(Figure 7i) Otago Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	0
1996	9	0.001	0.003	0.010	0.010	0.046	0.10
1997	9	0.006	0.007	0.010	0.010	0.014	0.02
1998	9	0.010	0.010	0.010	0.010	0.010	0.01
1999	9	0.005	0.005	0.005	0.005	0.008	0.01
2000	5	<0.005	<0.005	<0.005	<0.005	<0.005	<0.005
2001	5	<0.005	<0.005	<0.005	<0.005	<0.005	<0.005
2002	10	0.000	0.000	0.001	0.175	7.208	23.00
2003	10	0.000	0.000	0.002	0.128	0.375	0.45
2004	9	0.000	0.001	0.013	0.216	0.432	0.51
2005	10	0.000	0.000	0.000	0.019	0.375	0.48
2006	20	0.000	0.000	0.000	0.005	0.153	1.53
2007	24	0.000	0.000	0.001	0.026	0.607	2.15
2008	47	0.000	0.000	0.007	0.058	0.646	2.23
Change in Percentile Value Over Time²		-0.001	-0.001	-	0.005	0.169	0.77

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).

(Figure 7j) Southland Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	0
1996	0
1997	0
1998	6	6.6E-12	1.5E-09	0.000	0.00	0.69	1.2
1999	5	2.7E-05	1.3E-04	0.003	0.06	0.75	1.1
2000	4	2.5E-05	1.5E-04	0.006	0.05	0.69	1.0
2001	3	9.3E-07	1.3E-05	0.003	0.18	0.75	0.9
2002	4	3.9E-06	3.6E-05	0.005	0.14	0.85	1.1
2003	5	2.5E-07	3.2E-06	0.002	0.11	0.76	0.9
2004	4	4.9E-06	4.0E-05	0.005	0.07	0.71	1.0
2005	29	3.9E-05	2.9E-04	0.003	0.02	0.37	1.0
2006	25	7.3E-05	8.1E-04	0.002	0.01	0.23	1.5
2007	29	1.7E-04	1.0E-03	0.005	0.01	1.27	1.9
2008	27	5.0E-05	4.8E-04	0.001	0.02	0.21	1.5
Change in Percentile Value Over Time²		5.5E-06	6.4E-05	-	-	-	-

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).

(Figure 7k) Taranaki Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	2	0.003	0.030	0.050	1.660	3.64	4.80
1996	3	0.002	0.010	0.038	0.691	1.04	4.11
1997	2	0.000	0.001	0.010	0.745	1.38	2.20
1998	2	0.001	0.011	0.020	0.405	0.98	0.98
1999	2	0.000	0.006	0.009	0.559	0.94	0.94
2000	2	0.000	0.002	0.010	0.537	0.85	0.89
2001	2	0.000	0.000	0.006	0.740	0.88	0.88
2002	2	0.005	0.006	0.012	0.109	0.44	0.69
2003	2	0.005	0.005	0.007	0.020	0.48	0.72
2004	2	0.003	0.006	0.006	0.008	0.45	0.70
2005	2	0.005	0.005	0.006	0.010	0.45	0.69
2006	2	0.001	0.005	0.007	0.007	0.47	0.72
2007	2	0.005	0.007	0.008	0.019	0.03	0.03
2008	2	0.008	0.019	0.041	0.069	0.34	0.48
Change in Percentile Value Over Time²		-	-	-0.001	-0.074	-0.09	-0.11

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).

(Figure 7l) Tasman Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	0
1996	10	4.5E-05	1.5E-04	0.0064	0.14	1.47	2.5
1997	10	2.2E-06	2.9E-05	0.0051	0.09	1.57	2.6
1998	9	8.4E-10	3.1E-08	0.0000	0.02	1.66	2.6
1999	10	6.3E-07	1.7E-05	0.0011	0.12	1.55	2.6
2000	10	1.9E-07	4.9E-06	0.0003	0.17	1.51	2.5
2001	10	7.9E-05	5.3E-04	0.0090	0.23	1.43	2.3
2002	13	9.3E-06	4.1E-05	0.0020	0.02	1.18	2.5
2003	16	6.7E-05	1.6E-04	0.0048	0.02	0.93	2.7
2004	16	7.7E-05	5.8E-04	0.0070	0.02	0.87	2.6
2005	16	2.0E-04	1.4E-03	0.0058	0.02	0.88	2.6
2006	16	7.0E-07	4.8E-05	0.0020	0.02	0.89	2.6
2007	16	1.8E-05	1.1E-04	0.0055	0.02	0.93	2.6
2008	16	8.0E-06	2.9E-05	0.0015	0.03	1.02	2.6
Change in Percentile Value Over Time²		-	-	-	-	-0.070	-

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).

(Figure 7m) Waikato Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	0
1996	3	0.060	0.060	0.060	0.060	0.060	0.06
1997	6	0.000	0.000	0.000	0.003	0.043	0.06
1998	6	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01
1999	7	0.000	0.000	0.001	0.005	0.015	0.02
2000	7	0.020	0.020	0.020	0.020	0.020	0.02
2001	7	0.010	0.010	0.010	0.010	0.010	0.01
2002	18	0.000	0.000	0.001	0.007	0.234	1.04
2003	7	0.001	0.001	0.002	0.005	0.008	0.01
2004	0
2005	4	0.056	0.080	0.366	0.420	0.467	0.48
2006	98	0.000	0.000	0.001	0.009	0.238	4.40
2007	14	0.000	0.001	0.003	0.013	0.358	0.69
2008	84	0.000	0.000	0.001	0.009	0.458	3.00
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).

(Figure 7n) Wellington Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	9	2.7E-04	1.3E-03	0.0350	0.06	1.33	1.8
1996	22	1.4E-05	1.0E-04	0.0013	0.04	0.76	1.8
1997	31	6.7E-05	3.9E-04	0.0034	0.05	0.85	1.7
1998	49	1.1E-03	4.6E-03	0.0300	0.39	0.95	1.6
1999	49	7.3E-04	4.1E-03	0.0435	0.43	1.01	1.6
2000	50	1.7E-03	5.3E-03	0.0300	0.46	0.99	1.6
2001	47	8.7E-04	3.6E-03	0.0400	0.43	1.07	1.5
2002	47	1.4E-03	4.7E-03	0.0325	0.44	1.14	1.5
2003	48	1.1E-04	1.0E-03	0.0141	0.40	0.85	1.4
2004	60	2.6E-07	3.1E-06	0.0001	0.00	0.56	1.5
2005	64	7.2E-08	1.3E-06	0.0001	0.00	0.42	1.6
2006	65	1.4E-09	7.8E-08	0.0000	0.00	0.49	1.7
2007	65	4.0E-09	2.0E-07	0.0000	0.01	0.45	1.7
2008	63	1.7E-10	1.5E-08	0.0000	0.00	0.51	1.4
Change in Percentile Value Over Time²		-2.1E-05	-1.1E-04	-0.0026	-	-0.044	-0.018

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).

(Figure 7o) West Coast Region calculated percentiles and maximum values for manganese in groundwater (in mg/L), based on site-specific median values.

Parameter	n¹	Percentile					Max
Parameter	n¹	5th	25th	50th	75th	95th	Max
1995	0
1996	0
1997	0
1998	6	0.000	0.001	0.006	0.018	0.05	0.06
1999	7	0.001	0.003	0.005	0.012	0.04	0.05
2000	7	0.003	0.007	0.008	0.015	0.04	0.05
2001	7	0.002	0.004	0.008	0.024	0.05	0.05
2002	6	0.001	0.002	0.006	0.018	0.03	0.03
2003	7	0.004	0.006	0.019	0.027	0.06	0.07
2004	8	0.000	0.001	0.004	0.027	0.06	0.07
2005	8	0.001	0.002	0.010	0.029	0.07	0.10
2006	8	0.000	0.000	0.003	0.022	0.10	0.15
2007	8	0.000	0.000	0.002	0.011	0.42	0.63
2008	8	0.000	0.000	0.005	0.013	0.22	0.33
Change in Percentile Value Over Time²		-0.0001	-0.0003	-	-	0.01	0.02

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).

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