Dewey County, South Dakota
13 ZIP codes · Avg score 60/100 · Grade C · Updated 2026-06-04
Dewey County: 13 ZIP codes, mid-range safety grade.
How Dewey County Compares
How Dewey County Compares
Dewey County scores 0 points above the South Dakota state average (60/100) and 8 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-04
ZIP Code Risk Map
Water Quality Map: Dewey County, South Dakota
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 17.1 (asthma 13.3%, diabetes 18.2%)
Estimated additional annual cost per homeowner: $476, driven primarily by water_lead
Infrastructure: 0.372% avg pipe failure probability, 23% of ZIPs at high risk
67.2% of homes built before 1978 (lead paint era)
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $476
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
2,899 housing units in Dewey County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Dewey County
Remediation costs are relatively manageable for most homeowners in Dewey County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for Dewey County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 5 systems in Dewey County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Eagle Butte | 4,000 | 5 |
| 2 | Tri-county Rural Water System | 2,190 | 5 |
| 3 | TIMBER LAKE | 499 | 0 |
| 4 | Web Water Development Association | 20,750 | 0 |
| 5 | MOBRIDGE | 3,261 | 0 |
6 total water systems serve Dewey County.
All ZIP Codes in Dewey County
13 ZIP codes tracked in Dewey County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 57633 | Isabel | 83 | B | 0 | $63K |
| 2 | 57656 | Timber Lake | 83 | B | 0 | $87K |
| 3 | 57625 | Eagle Butte | 82 | B | 5 (1 health) | $72K |
| 4 | 57621 | Bullhead | 53 | D | 0 | — |
| 5 | 57630 | Glencross | 53 | D | 0 | — |
| 6 | 57631 | Glenham | 53 | D | 0 | $107K |
| 7 | 57636 | Lantry | 53 | D | 0 | $207K |
| 8 | 57639 | Little Eagle | 53 | D | 0 | — |
| 9 | 57641 | Mc Intosh | 53 | D | 0 | $63K |
| 10 | 57652 | Ridgeview | 53 | D | 0 | — |
| 11 | 57657 | Trail City | 53 | D | 0 | $75K |
| 12 | 57658 | Wakpala | 53 | D | 0 | $81K |
| 13 | 57661 | Whitehorse | 53 | D | 0 | — |
Recommended Buyer Guides for Dewey County
Filtered against federal data, fitted to local risks.
- Best Lead Paint Test Kits — 67.2% of homes built before 1978
Deep Dive Reports
Detailed analysis for Dewey County, South Dakota
Overview
Dewey County in South Dakota covers 13 ZIP codes with an average Home Safety Score of C (60/100).
1 of 13 ZIP codes have recorded EPA violations. 1 health-based violation have been documented.
← Back to South Dakota water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.