TABLE 1—
Characteristics of At-Risk and Not-At-Risk Community Water Systems Based on Drinking Water Supply Well Proximity to Oil and Gas Wells: Los Angeles County, CA, 2020
| At-Risk CWS (n = 47) | Not-at-Risk CWS (n = 125) | |
| Total population served, no. | 7 180 196 | 2 204 316 |
| CWS size, no. | ||
| Small (< 200 connections) | 0 | 47 |
| Medium (200‒9999 connections) | 24 | 61 |
| Large (≥ 10 000 connections) | 23 | 17 |
| Sociodemographics, mean % | ||
| Hispanic | 59.8 | 40.2 |
| Non-Hispanic White | 19.3 | 39.2 |
| Non-Hispanic Asian/Pacific Islander | 11.0 | 10.9 |
| Non-Hispanic Black | 7.5 | 6.5 |
| Non-Hispanic other race including multiracial | 2.0 | 2.8 |
| Non-Hispanic Native American | 0.2 | 0.3 |
| Linguistically isolated | 13.4 | 9.4 |
| Renters | 48.8 | 35.5 |
| Povertya | 37.9 | 36.0 |
| Median household income, mean $ | 66 214 | 66 810 |
| HOLC redlining grade,b mean % | ||
| A | 2.6 | 9.1 |
| B | 13.6 | 17.6 |
| C | 55.8 | 55.4 |
| D | 28.0 | 17.9 |
| Ungraded | 65.8 | 52.2 |
| Weighted redlining score (0‒100),c mean | 77.3 | 70.5 |
| ICE quartiled, mean % | ||
| 1 | 29.5 | 11.5 |
| 2 | 29.9 | 21.0 |
| 3 | 19.8 | 32.8 |
| 4 | 19.7 | 34.0 |
| Weighted ICE score (0‒100),e mean | 66.8 | 52.2 |
| Amount of supply wells within 1 km of an oil or gas well, no. (%) | ||
| Low (≤ 25%) | 10 (21) | 0 |
| Medium (26%–50%) | 16 (34) | 0 |
| High (51%–75%) | 6 (13) | 0 |
| Very high (76%–100%) | 15 (32) | 0 |
| Primary water source, no. (%) | ||
| Groundwater | 14 (29.8) | 76 (60.8) |
| Surface water | 33 (70.2) | 49 (39.2) |
Note. CWS = community water system; HOLC = Home Owners’ Loan Corporation; ICE = Index of Concentration at the Extremes. Descriptive statistics are provided for at-risk and not-at-risk CWSs based on their service area. An at-risk CWS was defined as having at least 1 water supply well within 1 km of an active, inactive, or storage or disposal well. Eleven systems had at least 1 supply well within 1 km of an active oil or gas well.
Poverty was defined as below twice the federal poverty level based on the US Census.
Only 85 out of 172 CWSs intersected with neighborhoods assigned a grade of A (“best”), B (“still desirable”), C (“definitely declining”), or D (“hazardous”; i.e., redlined) for investment by HOLC.
Weighted redlining scores closer to 100 indicate that a greater proportion of the CWS’s HOLC-graded area received lower HOLC grades (e.g., more D-graded areas).
We categorized ICE (‒1 to 1) into quartiles, with Q1 representing the highest concentration of racialized economic marginalization and Q4 the highest concentration of racialized economic privilege.
Weighted ICE scores closer to 100 indicate that a greater proportion of the CWS’s census tracts are marginalized.