Lake County, South Dakota
4 ZIP codes · Avg score 47/100 · Grade D · Updated 2026-06-04
Across Lake County, EPA compliance records for 4 ZIP codes fall well below average — documented health-based violations affect multiple areas, and the county's sustained low grade points to structural rather than temporary shortfalls in the underlying water systems.
How Lake County Compares
How Lake County Compares
Lake County scores 13 points below the South Dakota state average (60/100) and 21 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-04
Key Risk Factors
Health risk index: 13 (asthma 9.7%, diabetes 12%)
Estimated additional annual cost per homeowner: $1,143, driven primarily by flood
Infrastructure: 0.407% avg pipe failure probability, 75% of ZIPs at high risk
69.3% 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: $1,143
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
4,178 housing units in Lake 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 Lake County
Remediation costs are relatively manageable for most homeowners in Lake 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 Lake County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 4 systems in Lake County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Madison | 6,191 | 0 |
| 2 | Kingbrook I Rural Water System | 6,455 | 0 |
| 3 | Big Sioux Community Water System | 5,800 | 0 |
| 4 | Kingbrook Iii Rural Water System | 2,888 | 0 |
All ZIP Codes in Lake County
4 ZIP codes tracked in Lake County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 57042 | Madison | 55 | C | 0 | $218K |
| 2 | 57050 | Nunda | 53 | D | 0 | $225K |
| 3 | 57054 | Ramona | 40 | D | 0 | $109K |
| 4 | 57057 | Rutland | 40 | D | 0 | $367K |
Recommended Buyer Guides for Lake County
Independent picks. EPA-grounded. Matched here.
- Best Lead Paint Test Kits — 69.3% of homes built before 1978
- Best Radon Test Kits — EPA Radon Zone 1 (highest risk) dominant in county
- Best Sump Pumps — Flood is the top compound risk factor
- Best Mold Test Kits — Flood-driven moisture and mold risk
Overview
Lake County in South Dakota covers 4 ZIP codes with an average Home Safety Score of D (47/100).
No EPA violations recorded across any tracked ZIP codes in Lake County.
← 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.
What You Can Do
Lake County has a grade of D. Here are steps to protect your household.
Test your tap water
Order a certified lab test kit ($20-$50) to check for lead, bacteria, and other contaminants specific to your ZIP code.
Consider a certified water filter
NSF-certified filters can remove most common contaminants. Match the filter to your test results for best protection. Try our filter matcher
Contact your water utility
Request the latest Consumer Confidence Report (CCR) from your water provider. It details exactly what was found in your water supply.
Check for lead in your home
69.3% of homes in this county were built before 1978. Older plumbing and solder can leach lead into drinking water, especially in the morning.