Monona County, Iowa
9 ZIP codes · Avg score 65/100 · Grade C · Updated 2026-06-03
Tracking 9 ZIP codes in Monona County reveals a mixed picture — tap water quality varies meaningfully by location.
How Monona County Compares
How Monona County Compares
Monona County scores 6 points above the Iowa state average (59/100) and 3 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Monona County, Iowa
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 15 (asthma 10.1%, diabetes 13.1%)
Estimated additional annual cost per homeowner: $940, driven primarily by energy_code_gap
Infrastructure: 0.518% avg pipe failure probability, 100% of ZIPs at high risk
83% 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: $940
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
4,900 housing units in Monona 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 Monona County
Remediation costs are relatively manageable for most homeowners in Monona 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 Monona 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 Monona County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Soldier Water Supply | 180 | 5 |
| 2 | Ute Water Supply | 338 | 2 |
| 3 | Castana Municipal Water Supply | 103 | 1 |
| 4 | Mapleton Municipal Water Plant | 1,124 | 1 |
| 5 | Moorhead Water Supply | 189 | 1 |
9 total water systems serve Monona County.
All ZIP Codes in Monona County
9 ZIP codes tracked in Monona County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 51040 | Onawa | 70 | B | 0 | $140K |
| 2 | 51063 | Whiting | 70 | B | 0 | $116K |
| 3 | 51523 | Blencoe | 70 | B | 0 | $118K |
| 4 | 51010 | Castana | 66 | C | 1 | $108K |
| 5 | 51034 | Mapleton | 66 | C | 1 | $119K |
| 6 | 51060 | Ute | 65 | C | 2 | $104K |
| 7 | 51572 | Soldier | 62 | C | 5 | $125K |
| 8 | 51055 | Sloan | 61 | C | 0 | $209K |
| 9 | 51558 | Moorhead | 58 | C | 1 | $70K |
Recommended Buyer Guides for Monona County
Editorial-only picks, screened against the EPA detections on file.
- Best Lead Paint Test Kits — 83% of homes built before 1978
- Best Radon Test Kits — EPA Radon Zone 1 (highest risk) dominant in county
Deep Dive Reports
Detailed analysis for Monona County, Iowa
Overview
Monona County in Iowa covers 9 ZIP codes with an average Home Safety Score of C (65/100).
5 of 9 ZIP codes have recorded EPA violations. All violations are monitoring/reporting type.
← Back to Iowa 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.