Arsenic

City of Merced

Arsenic is a potent carcinogen and common contaminant in drinking water. Arsenic causes thousands of cases of cancer each year in the U.S. Click here to read more about arsenic.

MORE ABOUT THIS CONTAMINANT

340

Samples

Samples exceeding legal limit (MCL)

294

Samples exceeding
health guidelines

Testing results - average by year

Year	Average result	Samples taken	Detections	Range of results
2014	3.84 ppb	275	233	ND - 9.30 ppb
2015	3.87 ppb	23	21	ND - 5.90 ppb
2016	3.95 ppb	20	19	ND - 8.70 ppb
2017	3.90 ppb	2	2	1.80 ppb - 8.70 ppb
2018	3.10 ppb	1	1	3.10 ppb
2019	3.97 ppb	19	18	ND - 8.10 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.004 ppb

The EWG Health Guideline of 0.004 ppb for arsenic was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.

EPA Maximum Contaminant
Level (MCL) 10 ppb

The legal limit for arsenic, established in 2001, was based on costs for arsenic removal, as calculated at the time that the standard was set. This limit does not fully protect against the risk of cancer due to arsenic exposure.

ppb = parts per billion

All test results

Date	Lab ID	Result
2014-01-02	5810-004-1025	4.40 ppb
2014-01-02	5810-005-1025	4.00 ppb
2014-01-02	5810-020-1110	4.30 ppb
2014-01-02	5810-023-1020	7.70 ppb
2014-01-02	5810-051-1020	3.60 ppb
2014-01-09	5810-004-0854	3.80 ppb
2014-01-09	5810-004-1307	5.30 ppb
2014-01-09	5810-005-0857	ND
2014-01-09	5810-005-1304	4.40 ppb
2014-01-09	5810-008-0832	3.10 ppb
2014-01-09	5810-011-1445	6.70 ppb
2014-01-09	5810-015-1430	2.10 ppb
2014-01-09	5810-016-1350	ND
2014-01-09	5810-019-1109	2.70 ppb
2014-01-09	5810-020-0937	3.20 ppb
2014-01-09	5810-020-1340	5.00 ppb
2014-01-09	5810-022-1250	2.70 ppb
2014-01-09	5810-023-0900	6.60 ppb
2014-01-09	5810-023-1320	8.30 ppb
2014-01-09	5810-041-0955	5.80 ppb
2014-01-09	5810-042-1053	4.60 ppb
2014-01-09	5810-043-1031	5.50 ppb
2014-01-09	5810-048-1409	2.70 ppb
2014-01-09	5810-049-1140	3.10 ppb
2014-01-09	5810-051-1300	4.30 ppb
2014-01-09	5810-054-1318	2.80 ppb
2014-01-10	5810-001-0944	ND
2014-01-10	5810-002-0950	ND
2014-01-10	5810-003-0941	ND
2014-01-10	5810-021-0858	2.70 ppb
2014-01-16	5810-004-0851	3.80 ppb
2014-01-16	5810-005-0851	ND
2014-01-16	5810-020-0835	4.30 ppb
2014-01-16	5810-023-0858	5.60 ppb
2014-01-16	5810-051-0849	3.40 ppb
2014-01-23	5810-004-1118	4.10 ppb
2014-01-23	5810-005-1120	2.60 ppb
2014-01-23	5810-020-1105	4.00 ppb
2014-01-23	5810-023-1126	7.30 ppb
2014-01-23	5810-051-1123	2.40 ppb
2014-01-31	5810-004-0930	3.40 ppb
2014-01-31	5810-005-0928	ND
2014-01-31	5810-020-0900	3.20 ppb
2014-01-31	5810-023-0915	5.50 ppb
2014-01-31	5810-051-0925	2.10 ppb
2014-02-06	5810-004-1049	2.90 ppb
2014-02-06	5810-005-1045	ND
2014-02-06	5810-020-1030	2.10 ppb
2014-02-06	5810-023-1043	7.00 ppb
2014-02-06	5810-051-1048	3.30 ppb
2014-02-13	5810-004-0840	2.40 ppb
2014-02-13	5810-005-0836	2.80 ppb
2014-02-13	5810-020-0855	2.30 ppb
2014-02-13	5810-023-0830	7.90 ppb
2014-02-13	5810-051-0834	2.70 ppb
2014-02-21	5810-004-1115	4.00 ppb
2014-02-21	5810-005-1113	3.20 ppb
2014-02-21	5810-020-1100	5.00 ppb
2014-02-21	5810-023-1120	7.10 ppb
2014-02-21	5810-051-1110	2.90 ppb
2014-02-27	5810-004-1024	5.60 ppb
2014-02-27	5810-005-1020	3.30 ppb
2014-02-27	5810-020-0950	3.70 ppb
2014-02-27	5810-023-1038	7.60 ppb
2014-02-27	5810-051-1015	5.00 ppb
2014-03-06	5810-004-1057	3.20 ppb
2014-03-06	5810-005-1055	3.50 ppb
2014-03-06	5810-020-1040	5.10 ppb
2014-03-06	5810-023-1052	6.20 ppb
2014-03-06	5810-051-1048	3.60 ppb
2014-03-13	5810-004-1200	2.20 ppb
2014-03-20	5810-004-0920	2.90 ppb
2014-03-27	5810-004-1140	2.70 ppb
2014-03-27	5810-005-1138	ND
2014-03-27	5810-020-1255	2.30 ppb
2014-03-27	5810-023-1145	6.00 ppb
2014-03-27	5810-051-1135	4.10 ppb
2014-04-03	5810-004-1011	3.40 ppb
2014-04-03	5810-005-1008	ND
2014-04-03	5810-020-0955	3.20 ppb
2014-04-03	5810-023-1014	5.60 ppb
2014-04-10	5810-004-0855	3.30 ppb
2014-04-10	5810-005-0850	ND
2014-04-10	5810-020-1030	3.80 ppb
2014-04-10	5810-023-0905	8.60 ppb
2014-04-10	5810-051-0845	5.50 ppb
2014-04-17	5810-004-1228	3.50 ppb
2014-04-17	5810-005-1226	ND
2014-04-17	5810-020-1305	4.30 ppb
2014-04-17	5810-023-1231	7.80 ppb
2014-04-17	5810-051-1223	4.10 ppb
2014-04-25	5810-004-1141	2.90 ppb
2014-04-25	5810-005-1138	2.50 ppb
2014-04-25	5810-020-1115	5.60 ppb
2014-04-25	5810-023-1143	4.30 ppb
2014-04-25	5810-051-1135	4.00 ppb
2014-05-01	5810-004-1156	3.90 ppb
2014-05-01	5810-005-1151	2.70 ppb
2014-05-01	5810-020-1135	3.20 ppb
2014-05-01	5810-023-1158	6.50 ppb
2014-05-01	5810-051-1148	ND
2014-05-08	5810-004-0800	3.50 ppb
2014-05-08	5810-005-0811	2.60 ppb
2014-05-08	5810-020-0850	6.80 ppb
2014-05-08	5810-023-0806	4.00 ppb
2014-05-08	5810-051-0808	3.70 ppb
2014-05-15	5810-004-0900	3.90 ppb
2014-05-15	5810-005-0856	ND
2014-05-15	5810-020-0935	4.20 ppb
2014-05-15	5810-023-0904	5.40 ppb
2014-05-15	5810-051-0854	2.40 ppb
2014-05-22	5810-004-1110	3.50 ppb
2014-05-22	5810-005-1045	3.60 ppb
2014-05-22	5810-020-0915	6.80 ppb
2014-05-22	5810-023-1117	8.30 ppb
2014-05-22	5810-051-1059	3.90 ppb
2014-05-30	5810-004-0910	3.50 ppb
2014-05-30	5810-005-0916	ND
2014-05-30	5810-020-1040	7.30 ppb
2014-05-30	5810-023-0921	8.20 ppb
2014-05-30	5810-051-0913	3.70 ppb
2014-06-05	5810-004-0900	3.60 ppb
2014-06-05	5810-005-0825	5.60 ppb
2014-06-05	5810-020-0935	7.60 ppb
2014-06-05	5810-023-0835	7.70 ppb
2014-06-05	5810-051-0840	3.50 ppb
2014-06-12	5810-004-1318	4.50 ppb
2014-06-12	5810-005-1313	4.50 ppb
2014-06-12	5810-020-1358	6.90 ppb
2014-06-12	5810-023-1322	8.30 ppb
2014-06-12	5810-051-1307	5.40 ppb
2014-06-19	5810-004-0823	4.40 ppb
2014-06-19	5810-005-0833	4.30 ppb
2014-06-19	5810-020-0844	7.10 ppb
2014-06-19	5810-023-0836	8.90 ppb
2014-06-19	5810-051-0834	4.80 ppb
2014-06-26	5810-004-1221	2.40 ppb
2014-06-26	5810-005-1227	3.10 ppb
2014-06-26	5810-020-1310	4.80 ppb
2014-06-26	5810-023-1240	7.20 ppb
2014-06-26	5810-051-1224	3.70 ppb
2014-07-02	5810-004-0855	2.80 ppb
2014-07-02	5810-005-0901	2.60 ppb
2014-07-02	5810-020-1129	7.40 ppb
2014-07-02	5810-023-0905	7.70 ppb
2014-07-02	5810-051-0858	3.40 ppb
2014-07-10	5810-004-0949	2.80 ppb
2014-07-10	5810-005-0958	3.30 ppb
2014-07-10	5810-020-0935	6.90 ppb
2014-07-10	5810-023-1002	7.60 ppb
2014-07-10	5810-051-0955	4.00 ppb
2014-07-16	5810-004-0853	4.20 ppb
2014-07-16	5810-005-0850	2.80 ppb
2014-07-16	5810-020-1048	7.50 ppb
2014-07-16	5810-023-0844	7.60 ppb
2014-07-16	5810-051-0847	3.40 ppb
2014-07-24	5810-004-0755	4.00 ppb
2014-07-24	5810-005-0750	3.00 ppb
2014-07-24	5810-020-0905	8.00 ppb
2014-07-24	5810-023-0805	7.90 ppb
2014-07-24	5810-051-0745	5.70 ppb
2014-07-30	5810-004-1057	6.00 ppb
2014-07-30	5810-005-1042	5.50 ppb
2014-07-30	5810-020-1235	7.90 ppb
2014-07-30	5810-023-1035	9.30 ppb
2014-07-30	5810-051-1028	5.30 ppb
2014-08-07	5810-004-0702	3.90 ppb
2014-08-07	5810-005-0658	2.50 ppb
2014-08-07	5810-020-0820	7.10 ppb
2014-08-07	5810-023-0708	7.20 ppb
2014-08-07	5810-051-0655	3.50 ppb
2014-08-14	5810-004-0803	3.90 ppb
2014-08-14	5810-005-0800	2.40 ppb
2014-08-14	5810-020-0845	5.60 ppb
2014-08-14	5810-023-0807	6.50 ppb
2014-08-14	5810-051-0755	5.60 ppb
2014-08-21	5810-004-0815	3.10 ppb
2014-08-21	5810-005-0810	ND
2014-08-21	5810-020-1100	3.40 ppb
2014-08-21	5810-023-0840	6.70 ppb
2014-08-21	5810-051-0805	4.30 ppb
2014-08-27	5810-004-0830	3.10 ppb
2014-08-27	5810-005-0825	ND
2014-08-27	5810-020-1230	7.80 ppb
2014-08-27	5810-023-0835	5.70 ppb
2014-08-27	5810-051-0820	2.10 ppb
2014-09-04	5810-004-0700	ND
2014-09-04	5810-005-0706	ND
2014-09-04	5810-020-0802	3.70 ppb
2014-09-04	5810-023-0711	6.80 ppb
2014-09-04	5810-051-0717	ND
2014-09-11	5810-004-1005	ND
2014-09-11	5810-005-1005	ND
2014-09-11	5810-020-1020	4.20 ppb
2014-09-11	5810-023-1000	6.60 ppb
2014-09-11	5810-051-1008	3.40 ppb
2014-09-19	5810-004-1320	3.80 ppb
2014-09-19	5810-005-1310	2.50 ppb
2014-09-19	5810-020-1145	3.40 ppb
2014-09-19	5810-023-1324	6.10 ppb
2014-09-19	5810-051-1317	2.90 ppb
2014-09-25	5810-004-1050	3.80 ppb
2014-09-25	5810-005-1040	ND
2014-09-25	5810-020-0950	4.20 ppb
2014-09-25	5810-023-1100	4.60 ppb
2014-09-25	5810-051-1030	3.30 ppb
2014-10-01	5810-004-1035	2.10 ppb
2014-10-01	5810-005-1030	ND
2014-10-01	5810-020-1000	5.80 ppb
2014-10-01	5810-023-1040	5.60 ppb
2014-10-01	5810-051-1020	3.70 ppb
2014-10-08	5810-004-0915	ND
2014-10-08	5810-005-0925	ND
2014-10-08	5810-020-1045	5.30 ppb
2014-10-08	5810-023-0932	4.50 ppb
2014-10-08	5810-051-0945	ND
2014-10-15	5810-004-1315	3.00 ppb
2014-10-15	5810-005-1325	2.70 ppb
2014-10-15	5810-020-1300	5.70 ppb
2014-10-15	5810-023-1345	4.40 ppb
2014-10-15	5810-051-1332	4.60 ppb
2014-10-23	5810-004-1145	4.10 ppb
2014-10-23	5810-005-1145	2.20 ppb
2014-10-23	5810-020-1240	6.70 ppb
2014-10-23	5810-023-1129	5.20 ppb
2014-10-23	5810-051-1140	4.70 ppb
2014-10-29	5810-004-1105	5.00 ppb
2014-10-29	5810-005-1111	2.60 ppb
2014-10-29	5810-020-1030	5.40 ppb
2014-10-29	5810-023-1100	8.20 ppb
2014-10-29	5810-051-1107	6.60 ppb
2014-11-05	5810-004-0830	2.70 ppb
2014-11-05	5810-005-0844	ND
2014-11-05	5810-020-1345	4.90 ppb
2014-11-05	5810-023-0855	7.00 ppb
2014-11-05	5810-051-0850	ND
2014-11-13	5810-004-1427	ND
2014-11-13	5810-005-1425	ND
2014-11-13	5810-020-1455	ND
2014-11-13	5810-023-1432	6.10 ppb
2014-11-13	5810-051-1423	ND
2014-11-19	5810-004-1027	2.30 ppb
2014-11-19	5810-005-1023	ND
2014-11-19	5810-020-1007	4.90 ppb
2014-11-19	5810-023-1035	6.10 ppb
2014-11-19	5810-051-1017	ND
2014-11-24	5810-004-1153	ND
2014-11-24	5810-005-1150	ND
2014-11-24	5810-020-1130	2.60 ppb
2014-11-24	5810-023-1159	2.90 ppb
2014-11-25	5810-051-1145	ND
2014-12-03	5810-004-1025	ND
2014-12-03	5810-005-1032	3.30 ppb
2014-12-03	5810-020-1115	3.40 ppb
2014-12-03	5810-023-1020	5.00 ppb
2014-12-03	5810-051-1040	2.90 ppb
2014-12-10	5810-004-1000	3.80 ppb
2014-12-10	5810-005-1007	ND
2014-12-10	5810-020-1052	4.90 ppb
2014-12-10	5810-023-1015	3.90 ppb
2014-12-10	5810-051-1026	3.10 ppb
2014-12-18	5810-004-0828	2.10 ppb
2014-12-18	5810-005-0825	2.50 ppb
2014-12-18	5810-020-0857	4.70 ppb
2014-12-18	5810-023-0832	ND
2014-12-18	5810-051-0821	2.40 ppb
2014-12-22	5810-004-1255	3.40 ppb
2014-12-22	5810-005-1250	3.20 ppb
2014-12-22	5810-020-1325	4.70 ppb
2014-12-22	5810-023-1300	8.00 ppb
2014-12-22	5810-051-1245	2.90 ppb
2014-12-29	5810-004-1140	2.20 ppb
2014-12-29	5810-005-1141	ND
2014-12-29	5810-020-1230	3.10 ppb
2014-12-29	5810-051-1135	2.70 ppb
2015-01-08	5810-004-0830	5.30 ppb
2015-01-08	5810-005-0830	ND
2015-01-08	5810-020-0901	4.50 ppb
2015-01-08	5810-051-0825	3.50 ppb
2015-01-16	5810-004-0952	4.30 ppb
2015-01-16	5810-005-0959	4.20 ppb
2015-01-16	5810-020-0947	4.60 ppb
2015-01-16	5810-051-1045	5.60 ppb
2015-01-22	5810-004-1327	4.30 ppb
2015-01-22	5810-005-1320	4.00 ppb
2015-01-22	5810-020-1115	4.60 ppb
2015-01-28	5810-004-1210	3.20 ppb
2015-01-28	5810-005-1200	ND
2015-01-28	5810-020-1143	3.60 ppb
2015-01-28	5810-051-1155	5.20 ppb
2015-02-04	5810-004-0947	3.80 ppb
2015-02-04	5810-005-0943	4.10 ppb
2015-02-04	5810-020-1102	5.30 ppb
2015-02-04	5810-051-0935	5.00 ppb
2015-02-23	5810-004-0935	3.00 ppb
2015-02-23	5810-005-0950	2.20 ppb
2015-02-23	5810-023-0910	5.90 ppb
2015-02-23	5810-051-0915	2.70 ppb
2016-05-10	1233-057-1600	6.20 ppb
2016-09-01	9590-001-1205	2.20 ppb
2016-09-01	9590-002-1400	2.30 ppb
2016-09-01	9590-003-1255	2.20 ppb
2016-09-01	9590-004-1240	4.20 ppb
2016-09-01	9590-005-1340	3.90 ppb
2016-09-01	9590-011-0901	6.30 ppb
2016-09-01	9590-015-0810	ND
2016-09-01	9590-016-1030	3.00 ppb
2016-09-01	9590-019-1055	3.50 ppb
2016-09-01	9590-020-1120	7.40 ppb
2016-09-01	9590-021-1450	3.40 ppb
2016-09-01	9590-022-1335	3.10 ppb
2016-09-01	9590-023-1430	8.70 ppb
2016-09-01	9590-041-1020	2.60 ppb
2016-09-01	9590-043-1235	5.50 ppb
2016-09-01	9590-048-0910	2.40 ppb
2016-09-01	9590-049-0945	3.80 ppb
2016-09-01	9590-054-0846	3.90 ppb
2016-12-01	9590-042-0854	4.40 ppb
2017-03-09	9590-008-0840	3.20 ppb
2017-06-01		3.90 ppb*
2018-05-24	5810-008-1325	3.10 ppb
2019-08-06	5810-016-0820	3.30 ppb
2019-08-06	5810-042-0845	3.60 ppb
2019-08-06	5810-043-1000	5.30 ppb
2019-08-06	5810-048-0755	2.40 ppb
2019-08-06	5810-049-1030	3.60 ppb
2019-08-06	5810-054-1100	3.60 ppb
2019-08-08	5810-019-0820	3.80 ppb
2019-08-08	5810-020-0915	7.70 ppb
2019-08-08	5810-021-0725	3.40 ppb
2019-08-08	5810-041-0855	5.50 ppb
2019-08-13	5810-003-0747	2.90 ppb
2019-08-13	5810-004-0830	4.10 ppb
2019-08-13	5810-005-0850	4.30 ppb
2019-08-13	5810-015-0955	2.10 ppb
2019-08-13	5810-022-0725	3.10 ppb
2019-08-13	5810-023-0855	8.10 ppb
2019-09-19	5810-001-1230	ND
2019-10-03	5810-011-1220	5.10 ppb
2019-11-26	5810-008-0825	3.50 ppb

* Sample result is taken from the system's CCR report.