Table 1. Presumptive Contamination Model Validation by Selected States^a,f.

State	Known contamination sites, n	Consolidated county known contaminationb	Known contamination sites, n	Observed matchesc, n (%)	Expected matches (not observed)d, n (%)	Total matchese, n (%)
New Hampshire	469	2 Highest	189	30 (16%)	69 (37%)	99 (52%)
		2 Median	76	14 (18%)	32 (42%)	46 (61%)
California	253	2 Highest	52	39 (75%)	11 (21%)	50 (96%)
		2 Median	8	6 (75%)	2 (25%)	8 (100%)
Michigan	188	2 Highest	57	30 (53%)	22 (39%)	52 (91%)
		2 Median	2	0 (0%)	2 (100%)	2 (100%)
Minnesota	101	2 Highest	17	9 (53%)	6 (35%)	15 (88%)
		2 Median	2	2 (100%)	0 (0%)	2 (100%)
Maine	99	2 Highest	28	9 (32%)	11 (39%)	20 (71%)
		2 Median	11	2 (18%)	7 (64%)	9 (82%)
Vermont	62	2 Highest	30	15 (50%)	15 (50%)	30 (100%)
		2 Median	7	2 (29%)	5 (71%)	7 (100%)
Mississippi	9	2 Highest	5	5 (100%)	0 (0%)	5 (100%)
		2 Median	2	2 (100%)	0 (0%)	2 (100%)
Rhode Island	8	2 Highest	5	1 (20%)	3 (60%)	4 (80%)
		2 Median	3	2 (67%)	1 (33%)	3 (100%)
Washington	8	2 Highest	2	2 (100%)	0 (0%)	2 (100%)
		2 Median	2	1 (50%)	1 (50%)	2 (100%)
Tennessee	6	2 Highest	3	3 (100%)	0 (0%)	3 (100%)
		2 Median	2	2 (100%)	0 (0%)	2 (100%)
Total			503	176 (35%)	187 (37%)	363 (72%)

^aNotes: All county results included in Table S2.

^bConsolidated data from two counties with the highest and two counties with the median levels of known contamination sites within the state.

^cNumber of presumptive contamination sites with matched known contamination sites within the counties.

^dNumber of known contamination sites without presumptive contamination matches but are included in model parameters.

^eTotal known contamination sites incorporated by model parameters (observed matches + expected matches). Percentages may not add to 100 due to rounding.

^fSources: Author’s analysis.^60,61