|
Variable
|
City Demographics
|
County Demographics
|
|---|
|
Percent change (95% CI)
|
p-value
|
Percent change (95% CI)
|
p-value
|
|---|
|
Percent Black, non-Hispanica
|
−0.4 (−0.7, −0.2)
|
0.0016
|
−0.7 (−1.1, −0.3)
|
0.001
|
|
Percent Hispanica
|
0.3 (0.1, 0.5)
|
0.017
|
0.9 (0.6, 1.3)
|
< 0.0001
|
|
Percent povertya
|
−0.2 (−0.6, 0.1)
|
0.170
|
−1.9 (−2.5, −1.2)
|
< 0.0001
|
|
Percent home ownershipa
|
−0.4 (−0.6, −0.2)
|
0.0004
|
0.3 (−0.3, 0.8)
|
0.325
|
|
Percent urban householdsa
|
0.2 (0.1, 0.3)
|
< 0.0001
|
0.1 (0.0, 0.2)
|
0.222
|
|
System size: Smallb
|
11.8 (5.5, 18.5)
|
0.0002
|
11.4 (5.2, 18.0)
|
0.0002
|
|
System size: Mediumb
|
12.3 (3.8, 21.5)
|
0.004
|
14.1 (5.6, 23.3)
|
0.0009
|
|
System size: Largeb
|
22.8 (12.2, 34.4)
|
< 0.0001
|
29.7 (18.6, 41.8)
|
< 0.0001
|
|
System size: V. Largeb
|
21.2 (−2.5, 50.5)
|
0.083
|
34.7 (8.7, 67.1)
|
0.007
|
|
Source water: Groundwaterc
|
35.8 (24.9, 47.7)
|
< 0.0001
|
35.2 (24.4, 47.0)
|
< 0.0001
|
|
Percent croplanda
|
0.5 (0.3, 0.6)
|
< 0.0001
|
0.4 (0.2, 0.6)
|
< 0.0001
|
|
Livestock per 100 acresa
|
0.1 (0.0, 0.2)
|
0.123
|
0.1 (−0.1, 0.2)
|
0.313
|
|
Region: Northeastd
|
62.3 (−8.8, 189)
|
0.100
|
−13.8 (−52.2, 55.5)
|
0.622
|
|
Region: Southd
|
48.2 (−13.8, 155)
|
0.155
|
−3.2 (−44.7, 69.6)
|
0.910
|
|
Region: Westd
|
82.1 (2.4, 224)
|
0.041
|
−42.9 (−67.5, 0.2)
|
0.051
|
- Notes: Percent change in nitrate concentration from pooled regression results using city- and county-level demographic, land use, and water system characteristics. Analyses based only on CWSs with available information about both the cities and counties served (N = 19,987). Models include state-specific random intercepts and a fixed intercept term
- aContinuous predictor, table estimates reflect effect of one-unit change in the predictor
- bReferent group: very small systems. cReferent group: surface water. dReferent group: Midwest
