County Sampling Summaries

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Select a county on the map below to view county sampling results.

1989 - 2020 Statewide Sampling Summary

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The following table summarizes nitrate and pesticide data collected by the program.

Location	# Wells Sampled	# Wells with		# Wells That Exceeded		# Samples Collected	# Samples with		# Samples That Exceeded		Most Frequently Detected Pesticide
		Nitrate	Pesticide	Nitrate Standard	Pesticide Standard		Nitrate	Pesticide	Nitrate Standard	Pesticide Standard
All	1507	1366	415	352	10	4490	4269	1795	1936	16	Metolachlor ESA
Arkansas River Basin	160	151	25	30	1	279	264	45	45	1	Metolachlor ESA
Front Range Urban	172	147	70	30	0	417	375	103	64	0	Prometon
High Plains	185	185	25	25	1	217	216	31	29	1	Desethyl Atrazine
Lincoln County	28	28	1	4	0	28	28	1	4	0	Desethyl Atrazine
Lower South Platte	36	36	32	23	3	184	184	130	76	8	Metolachlor ESA
Mountainous Region	27	22	0	0	0	27	22	0	0	0
North Park	42	25	0	0	0	46	28	0	0	0
Northwest	33	29	0	0	0	38	32	0	0	0
Pikes Peak	49	43	0	1	0	49	43	0	1	0
San Luis Valley	219	214	53	44	1	598	574	90	171	1	Metolachlor ESA
South Platte River Basin	155	147	45	55	0	189	178	51	66	0	Metolachlor ESA
Southwest	43	33	1	0	0	43	33	1	0	0	Imazapyr
Weld County Domestic	25	25	24	18	2	247	243	96	127	2	Triazine (ELISA)
Weld County Irrigation	90	89	76	81	0	977	952	417	729	0	Triazine (ELISA)
Weld County Monitoring	42	42	42	36	2	946	944	809	619	3	Metolachlor ESA
West Slope	82	51	1	3	0	82	51	1	3	0	Malathion
West Slope - Tri Rivers	63	52	19	2	0	67	55	19	2	0	Alachlor ESA
Wet Mountain Valley	56	47	1	0	0	56	47	1	0	0	Picloram

Statewide Sampling Summary By Year

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The following table summarizes nitrate and pesticide data collected by the program.

Year	Location	# Wells Sampled	# Wells with		# Wells That Exceeded		# Samples Collected	# Samples with		# Samples That Exceeded		Most Frequently Detected Pesticide
			Nitrate	Pesticide	Nitrate Standard	Pesticide Standard		Nitrate	Pesticide	Nitrate Standard	Pesticide Standard
2020	All	20	20	14	11	0	20	20	14	11	0	Metolachlor ESA
2019	All	135	129	84	47	0	134	128	83	46	0	Metolachlor ESA
2019	Lower South Platte	8	8	7	4	0	8	8	7	4	0	Metolachlor ESA
2019	San Luis Valley	49	45	18	7	0	49	45	18	7	0	Metolachlor ESA
2019	South Platte River Basin	52	50	33	20	0	52	50	33	20	0	Metolachlor ESA
2019	Weld County Domestic	1	1	1	0	0	1	1	1	0	0	Metolachlor ESA & Metolachlor OA
2019	Weld County Monitoring	25	25	25	16	0	24	24	24	15	0	Metolachlor ESA
2018	All	134	122	71	44	1	233	221	170	98	1	Metolachlor ESA
2018	Lower South Platte	32	32	28	15	1	33	33	29	15	1	Metolachlor ESA
2018	North Park	25	17	0	0	0	25	17	0	0	0
2018	Northwest	33	29	0	0	0	33	29	0	0	0
2018	South Platte River Basin	10	10	10	4	0	10	10	10	4	0	Metolachlor ESA
2018	Weld County Monitoring	34	34	33	25	0	132	132	131	79	0	Metolachlor ESA
2017	All	84	73	25	23	1	203	192	143	79	1	Metolachlor ESA
2017	High Plains	19	19	2	6	0	19	19	2	6	0	Picloram
2017	Southwest	43	33	1	0	0	43	33	1	0	0	Imazapyr
2017	Weld County Monitoring	22	21	22	17	1	141	140	140	73	1	Metolachlor ESA
2016	All	192	186	92	56	0	192	186	93	56	0	Metolachlor ESA
2016	Arkansas River Basin	18	18	13	4	0	18	18	13	4	0	Imazapyr
2016	Front Range Urban	63	61	26	12	0	63	61	26	12	0	Imazapyr
2016	High Plains	17	17	2	5	0	17	17	2	5	0	Alachlor & Alachlor ESA & Alachlor OA & Desethyl Atrazine
2016	Lower South Platte	22	22	19	10	0	23	23	20	10	0	Metolachlor ESA
2016	San Luis Valley	39	35	10	6	0	38	34	10	6	0	Metolachlor ESA
2016	Weld County Domestic	7	7	0	3	0	7	7	0	3	0
2016	Weld County Irrigation	3	3	0	2	0	3	3	0	2	0
2016	Weld County Monitoring	23	23	22	14	0	23	23	22	14	0	Metolachlor ESA
2015	All	34	34	27	17	0	98	98	91	49	0	Metolachlor ESA
2015	High Plains	13	13	6	1	0	13	13	6	1	0	Desethyl Atrazine
2015	Weld County Monitoring	21	21	21	16	0	85	85	85	48	0	Metolachlor ESA
2014	All	65	65	40	40	0	107	107	81	68	0	Metolachlor ESA
2014	Lower South Platte	20	20	16	7	0	20	20	16	7	0	Metolachlor ESA
2014	Weld County Domestic	8	8	3	3	0	8	8	3	3	0	Metolachlor ESA & Metolachlor OA
2014	Weld County Irrigation	16	16	0	12	0	16	16	0	12	0
2014	Weld County Monitoring	21	21	21	18	0	63	63	62	46	0	Metolachlor ESA
2013	All	164	155	58	60	1	206	197	97	86	1	Metolachlor ESA
2013	Front Range Urban	63	58	22	12	0	63	58	21	12	0	Prometon
2013	San Luis Valley	40	36	7	5	0	40	36	7	5	0	Metolachlor ESA
2013	Weld County Domestic	11	11	7	4	0	11	11	7	4	0	Metolachlor ESA
2013	Weld County Irrigation	28	28	0	20	0	28	28	0	20	0
2013	Weld County Monitoring	22	22	22	19	1	64	64	62	45	1	Metolachlor ESA
2012	All	118	118	50	48	1	146	146	76	62	1	Metolachlor ESA
2012	Arkansas River Basin	16	16	5	0	0	16	16	5	0	0	Metolachlor ESA
2012	Lincoln County	28	28	1	4	0	28	28	1	4	0	Desethyl Atrazine
2012	Lower South Platte	20	20	16	5	1	20	20	16	5	1	Metolachlor ESA
2012	Weld County Domestic	12	12	6	6	0	12	12	6	6	0	Metolachlor ESA
2012	Weld County Irrigation	20	20	0	15	0	20	20	0	15	0
2012	Weld County Monitoring	22	22	22	18	0	50	50	48	32	0	Metolachlor ESA
2011	All	121	119	33	50	0	121	119	33	50	0	Metolachlor ESA
2011	High Plains	19	19	5	3	0	19	19	5	3	0	Alachlor ESA & Desethyl Atrazine
2011	Lower South Platte	1	1	1	1	0	1	1	1	1	0	Alachlor ESA & Atrazine & Bromacil & Desethyl Atrazine & Desisopropyl Atrazine & Diuron & Hydroxy Atrazine & Metolachlor ESA & Simazine
2011	San Luis Valley	43	41	7	6	0	43	41	7	6	0	Metolachlor ESA
2011	Weld County Domestic	13	13	0	5	0	13	13	0	5	0
2011	Weld County Irrigation	24	24	0	17	0	24	24	0	17	0
2011	Weld County Monitoring	21	21	20	18	0	21	21	20	18	0	Metolachlor ESA
2010	All	168	164	73	64	1	174	170	78	70	6	Metolachlor ESA
2010	Arkansas River Basin	19	19	9	1	0	19	19	9	1	0	Metolachlor ESA
2010	Front Range Urban	63	60	23	9	0	64	61	23	10	0	Imazapyr
2010	Lower South Platte	22	22	17	7	1	27	27	22	12	6	Metolachlor ESA
2010	Weld County Domestic	14	14	0	8	0	14	14	0	8	0
2010	Weld County Irrigation	26	25	0	20	0	26	25	0	20	0
2010	Weld County Monitoring	24	24	24	19	0	24	24	24	19	0	Metolachlor ESA
2009	All	176	161	66	50	0	176	161	66	50	0	Metolachlor ESA
2009	San Luis Valley	43	40	23	3	0	43	40	23	3	0	Metolachlor ESA
2009	Weld County Domestic	14	14	0	8	0	14	14	0	8	0
2009	Weld County Irrigation	32	31	0	18	0	32	31	0	18	0
2009	Weld County Monitoring	24	24	24	19	0	24	24	24	19	0	Atrazine & Desethyl Atrazine & Metolachlor ESA & Prometon
2009	West Slope - Tri Rivers	63	52	19	2	0	63	52	19	2	0	Alachlor ESA
2008	All	194	185	22	74	0	194	185	22	74	0	Tebuthiuron
2008	Arkansas River Basin	19	17	4	4	0	19	17	4	4	0	Ethoprop
2008	Front Range Urban	67	62	4	12	0	67	62	4	12	0	Bromacil
2008	High Plains	20	19	2	5	0	20	19	2	5	0	Dicamba
2008	Lower South Platte	21	21	2	8	0	21	21	2	8	0	Atrazine & Clopyralid & Desethyl Atrazine & MCPA & Metalaxyl
2008	Weld County Domestic	13	13	0	7	0	13	13	0	7	0
2008	Weld County Irrigation	31	30	0	21	0	31	30	0	21	0
2008	Weld County Monitoring	23	23	10	17	0	23	23	10	17	0	Tebuthiuron
2007	All	133	126	12	44	0	133	126	12	44	0	Metolachlor & Metribuzin
2007	Front Range Urban	45	42	0	5	0	45	42	0	5	0
2007	San Luis Valley	33	30	6	8	0	33	30	6	8	0	Metolachlor & Metribuzin
2007	Weld County Domestic	14	14	2	5	0	14	14	2	5	0	Diazinon OA & Dimethoate
2007	Weld County Irrigation	24	23	3	15	0	24	23	3	15	0	Dichlorvos
2007	Weld County Monitoring	17	17	1	11	0	17	17	1	11	0	Metalaxyl
2006	All	109	102	13	47	0	109	102	13	47	0	Desethyl Atrazine
2006	Pikes Peak	49	43	0	1	0	49	43	0	1	0
2006	Weld County Domestic	4	4	0	2	0	4	4	0	2	0
2006	Weld County Irrigation	39	38	0	32	0	39	38	0	32	0
2006	Weld County Monitoring	17	17	13	12	0	17	17	13	12	0	Desethyl Atrazine
2005	All	158	141	18	58	0	158	141	18	58	0	Desethyl Atrazine
2005	Arkansas River Basin	20	17	2	1	0	20	17	2	1	0	Desethyl Atrazine & Metolachlor
2005	Front Range Urban	40	32	3	5	0	40	32	3	5	0	MCPP
2005	Mountainous Region	27	22	0	0	0	27	22	0	0	0
2005	Weld County Domestic	4	4	0	3	0	4	4	0	3	0
2005	Weld County Irrigation	49	48	0	35	0	49	48	0	35	0
2005	Weld County Monitoring	18	18	13	14	0	18	18	13	14	0	Desethyl Atrazine
2004	All	101	98	69	53	0	101	98	69	53	0	Triazine (ELISA)
2004	Arkansas River Basin	19	18	4	1	0	19	18	4	1	0	Desethyl Atrazine
2004	Weld County Domestic	14	14	12	7	0	14	14	12	7	0	Triazine (ELISA)
2004	Weld County Irrigation	49	47	45	34	0	49	47	45	34	0	Triazine (ELISA)
2004	Weld County Monitoring	19	19	8	11	0	19	19	8	11	0	Desethyl Atrazine
2003	All	68	67	42	44	0	69	67	42	44	0	Triazine (ELISA)
2003	Weld County Domestic	4	4	4	3	0	4	4	4	3	0	Triazine (ELISA)
2003	Weld County Irrigation	45	44	33	29	0	46	44	33	29	0	Triazine (ELISA)
2003	Weld County Monitoring	19	19	5	12	0	19	19	5	12	0	Atrazine & Desethyl Atrazine & Metolachlor
2002	All	118	107	43	45	0	118	107	43	45	0	Triazine (ELISA)
2002	Weld County Domestic	4	4	3	2	0	4	4	3	2	0	Triazine (ELISA)
2002	Weld County Irrigation	39	37	24	30	0	39	37	24	30	0	Triazine (ELISA)
2002	Weld County Monitoring	19	19	15	13	0	19	19	15	13	0	Desethyl Atrazine
2002	Wet Mountain Valley	56	47	1	0	0	56	47	1	0	0	Picloram
2001	All	108	107	66	62	1	108	107	66	62	1	Triazine (ELISA)
2001	Lower South Platte	19	19	9	7	0	19	19	9	7	0	Desethyl Atrazine
2001	San Luis Valley	7	7	0	1	0	7	7	0	1	0
2001	Weld County Domestic	18	18	10	9	0	18	18	10	9	0	Desethyl Atrazine
2001	Weld County Irrigation	46	45	33	33	0	46	45	33	33	0	Triazine (ELISA)
2001	Weld County Monitoring	18	18	14	12	1	18	18	14	12	1	Metolachlor
2000	All	137	118	61	64	0	137	118	61	64	0	Triazine (ELISA)
2000	North Park	21	11	0	0	0	21	11	0	0	0
2000	San Luis Valley	33	31	8	10	0	33	31	8	10	0	Metolachlor
2000	Weld County Domestic	4	4	3	2	0	4	4	3	2	0	Triazine (ELISA)
2000	Weld County Irrigation	50	49	39	35	0	50	49	39	35	0	Triazine (ELISA)
2000	Weld County Monitoring	19	19	11	15	0	19	19	11	15	0	Desethyl Atrazine
2000	West Slope	10	4	0	2	0	10	4	0	2	0
1999	All	77	76	67	54	0	77	76	67	54	0	Triazine (ELISA)
1999	Lower South Platte	4	4	1	3	0	4	4	1	3	0	Atrazine & Desisopropyl Atrazine
1999	Weld County Domestic	4	4	3	3	0	4	4	3	3	0	Triazine (ELISA)
1999	Weld County Irrigation	49	48	46	33	0	49	48	46	33	0	Triazine (ELISA)
1999	Weld County Monitoring	20	20	17	15	0	20	20	17	15	0	Desethyl Atrazine
1998	All	190	160	77	62	0	191	160	77	62	0	Triazine (ELISA)
1998	High Plains	18	18	3	1	0	18	18	3	1	0	Atrazine & Desethyl Atrazine
1998	Northwest	5	3	0	0	0	5	3	0	0	0
1998	Weld County Domestic	22	22	13	12	0	22	22	13	12	0	Atrazine & Desethyl Atrazine
1998	Weld County Irrigation	50	49	46	35	0	51	49	46	35	0	Triazine (ELISA)
1998	Weld County Monitoring	19	18	14	13	0	19	18	14	13	0	Desethyl Atrazine
1998	West Slope	72	47	1	1	0	72	47	1	1	0	Malathion
1998	West Slope - Tri Rivers	4	3	0	0	0	4	3	0	0	0
1997	All	187	185	79	63	1	188	185	79	63	1	Triazine (ELISA)
1997	High Plains	111	111	11	8	1	111	111	11	8	1	Atrazine
1997	Weld County Domestic	4	4	3	4	0	4	4	3	4	0	Triazine (ELISA)
1997	Weld County Irrigation	53	51	50	37	0	54	51	50	37	0	Triazine (ELISA)
1997	Weld County Monitoring	19	19	15	14	0	19	19	15	14	0	Desethyl Atrazine & Prometon
1996	All	173	156	101	86	0	220	198	102	108	0	Desethyl Atrazine
1996	Front Range Urban	71	55	25	7	0	71	55	25	7	0	Prometon
1996	San Luis Valley	16	16	0	12	0	58	58	0	34	0
1996	Weld County Domestic	4	4	2	3	0	5	4	3	3	0	Atrazine & Desethyl Atrazine & Prometon & Triazine (ELISA)
1996	Weld County Irrigation	63	62	57	50	0	67	62	57	50	0	Triazine (ELISA)
1996	Weld County Monitoring	19	19	17	14	0	19	19	17	14	0	Desethyl Atrazine
1995	All	133	133	78	88	2	183	181	79	113	2	Atrazine
1995	Arkansas River Basin	29	29	7	15	1	29	29	7	15	1	Atrazine
1995	San Luis Valley	16	16	0	10	0	64	64	0	35	0
1995	Weld County Domestic	23	23	20	11	1	25	23	21	11	1	Atrazine
1995	Weld County Irrigation	49	49	40	41	0	49	49	40	41	0	Atrazine
1995	Weld County Monitoring	16	16	11	11	0	16	16	11	11	0	Atrazine
1994	All	197	188	1	64	0	245	236	1	87	0	2,4-D
1994	Arkansas River Basin	139	130	1	19	0	139	130	1	19	0	2,4-D
1994	San Luis Valley	16	16	0	10	0	64	64	0	33	0
1994	Weld County Domestic	2	2	0	1	0	2	2	0	1	0
1994	Weld County Irrigation	40	40	0	34	0	40	40	0	34	0
1993	All	188	184	11	53	1	188	184	11	53	1	Metribuzin
1993	San Luis Valley	126	124	11	23	1	126	124	11	23	1	Metribuzin
1993	South Platte River Basin	47	45	0	18	0	47	45	0	18	0
1993	Weld County Monitoring	15	15	0	12	0	15	15	0	12	0
1992	All	111	103	8	45	1	111	103	8	45	1	Atrazine
1992	South Platte River Basin	76	69	6	22	0	76	69	6	22	0	Atrazine
1992	Weld County Domestic	20	19	2	11	1	20	19	2	11	1	Alachlor & Atrazine
1992	Weld County Monitoring	15	15	0	12	0	15	15	0	12	0
1991	All	49	49	0	44	0	49	49	0	44	0
1991	Weld County Domestic	2	2	0	2	0	2	2	0	2	0
1991	Weld County Irrigation	47	47	0	42	0	47	47	0	42	0
1990	All	50	50	0	48	0	51	51	0	48	0
1990	Weld County Domestic	2	2	0	2	0	2	2	0	2	0
1990	Weld County Irrigation	48	48	0	46	0	49	49	0	46	0
1989	All	50	50	0	43	0	50	50	0	43	0
1989	Weld County Domestic	2	2	0	1	0	2	2	0	1	0
1989	Weld County Irrigation	48	48	0	42	0	48	48	0	42	0