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	Annual Toxics Summary Stockton-Hazelton Street FAQs Perchloroethylene parts per billion

Read About Estimated Risk

Year	Months Present	Minimum	Median	Mean	90th Percentile	Maximum	Standard Deviation	Number of Observations	Detection Limit	Estimated Risk
2025		*	*	*	*	*	*	0	*	*
2024		*	*	*	*	*	*	0	*	*
2023		*	*	*	*	*	*	0	*	*
2022		*	*	*	*	*	*	0	*	*
2021		0.005	0.005	*	0.005	0.03	0.007	18	0.01	*
2020		0.005	*	*	*	0.005	0.000	7	0.01	*
2019		0.005	0.005	0.009	0.02	0.05	0.010	29	0.01	1
2018		0.005	0.005	0.006	0.01	0.02	0.003	30	0.01	0.7
2017		0.005	0.005	0.006	0.01	0.02	0.004	28	0.01	0.7
2016		0.005	0.005	0.015	0.04	0.06	0.016	31	0.01	2
2015		0.005	0.005	0.008	0.02	0.02	0.005	30	0.01	1
2014		0.005	0.005	0.009	0.02	0.02	0.005	32	0.01	1
2013		0.005	0.005	0.011	0.02	0.04	0.008	30	0.01	1
2012		0.005	0.005	0.010	0.02	0.05	0.008	30	0.01	1
2011		0.005	0.005	0.010	0.02	0.02	0.006	30	0.01	1
2010		0.005	0.01	0.010	0.02	0.02	0.005	30	0.01	1
2009		0.005	0.01	0.014	0.02	0.07	0.014	31	0.01	2
2008		0.005	0.02	0.015	0.03	0.03	0.009	31	0.01	2
2007		0.005	0.02	0.020	0.03	0.07	0.014	30	0.01	2
2006		0.005	0.02	0.018	0.03	0.05	0.011	30	0.01	2
2005		0.005	0.02	0.024	0.04	0.09	0.019	31	0.01	3
2004		0.005	0.02	0.022	0.04	0.06	0.015	30	0.01	3
2003		0.005	0.03	0.030	0.04	0.15	0.028	30	0.01	3
2002		0.01	0.03	0.035	0.06	0.09	0.020	28	0.01	4
2001		0.01	0.04	0.053	0.12	0.26	0.053	31	0.01	6
2000		0.01	0.04	0.108	0.23	0.72	0.141	31	0.01	13
1999		0.01	0.05	*	0.12	0.26	0.065	22	0.01	*
1998		0.005	0.02	0.033	0.07	0.10	0.029	29	0.01	4
1997		0.005	0.05	0.090	0.26	0.44	0.114	28	0.01	10
1996		0.01	0.04	0.068	0.16	0.35	0.075	31	0.01	8
1995		0.02	0.05	0.061	0.11	0.22	0.044	30	0.01	7
1994		0.005	0.04	0.066	0.15	0.24	0.062	31	0.01	8
1993		0.02	0.07	*	0.17	0.86	0.175	33	0.01	*
1992		0.04	0.11	0.120	0.20	0.38	0.076	28	0.01	14
1991		0.04	0.10	0.113	0.19	0.22	0.050	29	0.01	13
1990		0.04	0.11	0.129	0.22	0.30	0.068	30	0.01	15
1989		0.04	0.12	0.135	0.19	0.29	0.058	23	0.01	16

	Notes:	Values below the Limit of Detection (LoD) assumed to be ½ LoD. Means and risks shown only for years with data in all 12 months. "*" means there was insufficient or no data available to determine the value.