Clark, SD: High Radon Risk — 70/100 (2026)
1 ZIP code · 4 water systems · Updated 2026-06-03
Water systems serving Clark hold a strong EPA compliance record — the city places among the better-performing areas in SD with few health-based violations on file.
How Clark Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Clark Water
- Average lead level: 0.001 mg/L.
- Homes built before 1986: 81% — older plumbing may contain lead solder.
- Estimated remediation: $2,400 per household.
- CDC health risk index: 14.15 — above typical levels.
Who Supplies Your Water in Clark
Federal drinking water records identify 4 systems in Clark, SD. The leading 3 providers serve the largest share of residential connections, each operating as a separate entity with its own rate authority, infrastructure management, and EPA compliance obligations — so service conditions are not uniform city-wide.
Overview
We track water quality and home safety data for 1 ZIP code in Clark, South Dakota (population ~1,760), covering 4 community water systems serving approximately 6,790 people region-wide.
No EPA violations recorded across any ZIP codes in Clark — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Clark: B (70/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Clark water systems draw from: Groundwater.
Lead & Copper
- Average lead level (90th percentile): 0.0010 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 1 (High Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 57225 | B | Clark Rural Water System | 2,325 |
All ZIP Codes in Clark
- 57225 [B]
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
Health Outcomes in Clark
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
Housing & Infrastructure in Clark
With 81% of homes built before 1986, lead solder in plumbing is a potential concern. The EPA banned lead solder in 1986, but many older homes retain original plumbing.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
Viewed through the lens of construction era, Clark is predominantly an older city — a median build year of 1955 puts most of the residential inventory in the range where pre-1986 plumbing materials were the standard.
Over half of homes in Clark were built before 1986, when lead solder was banned. Older plumbing may leach lead into drinking water, especially with corrosive water chemistry.
Source: U.S. Census Bureau ACS B25034.
Cost Context: What Remediation Means for Clark Homeowners
Although the Clark remediation share is moderate, it remains reachable for most homeowners who plan for the expense in advance.
Remediation costs are moderate relative to home values in Clark. The estimated $1,600–$3,300 range is manageable for most homeowners but still worth budgeting for. Home values are 17% below the South Dakota average.
Lead Exposure Risk for Children in Clark
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
Practically, the structural drivers in Clark — 81% pre-rule stock and citywide monitoring at or beyond the regulatory benchmark — make an in-home draw the practical way to translate aggregate averages into the specific conditions at one address.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Flood & Climate Risk in Clark
NFIP records stretching across multiple decades show Clark accumulating 4 claims and carrying 100% of its ZIP codes inside FEMA flood zones — evidence of meaningful exposure that extends beyond isolated incidents. The mechanisms linking flooding to water quality haven't changed: treatment facilities can be overwhelmed, wells can be infiltrated, and distribution systems can experience backflow. For a community at this exposure level, those mechanisms shift from hypothetical to periodically relevant.
Clark has a moderate flood history with 4 FEMA claims averaging $6,767 per payout. 100% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$2,400</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
Deep Dive Reports
Detailed analysis for Clark, SD