States › South Dakota › Clark County

Clark County, SD Water Quality

Water quality data for 5 public water systems serving Clark County, South Dakota — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 5 water systems · 12 cities
✅
Excellent — All Systems Performing Well

Water quality across the county is outstanding with minimal violations and very low lead levels.

A

Clark County Earns a A

Clark County: 12 communities across 5 water systems. 100.0% have no open violations.

  • Median lead where detected: 2.00 ppb
  • 5 communities with a lead detection, 7 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 0 with significant inspection deficiencies
  • 100.0% of communities have no open violations
2 ppb
Median Lead Level
County-wide, 90th percentile
5
Water Systems
Active CWS & NTNCWS
100%
Violation-Free
No active violations on record
How we grade counties: MyWaterIQ uses EPA SDWIS enforcement data — actual MCL violations and lead test results — not the aspirational MCLG targets used by some sites. A grade reflects real compliance history, not theoretical risk. Learn more →

Cities by Water Quality

⭐ Best Performing
  • Clark
    Not detected
    No federal limits exceeded on record
    B
  • Mayfield Colony
    Not detected
    No federal limits exceeded on record
    B
  • Hillcrest Colony
    Not detected
    No federal limits exceeded on record
    B
  • Collins Colony
    2.00 ppb
    No federal limits exceeded on record
    B
  • Bradley
    Not detected
    No federal limits exceeded on record
    B
⚠ Needs Attention
  • Garden City
    1.00 ppb
    Copper above the 1,300 ppb action level
    C
  • Willow Lake
    1.00 ppb
    2 health-based violations since 2015
    B
  • Vienna
    4.00 ppb
    1 health-based violation since 2015
    A
  • Naples
    4.00 ppb
    1 health-based violation since 2015
    A
  • Clark
    Not detected
    No federal limits exceeded on record
    B
County Lead Level — Median 2 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 2 ppb — 13.3% of the federal action level
Systems by Lead Level
Under 5 ppb
5
No Data
7

All Cities in Clark County

Clark Not detected B
Willow Lake 1.00 ppb B
Mayfield Colony Not detected B
Hillcrest Colony Not detected B
Collins Colony 2.00 ppb B
Bradley Not detected B
Vienna 4.00 ppb A
Naples 4.00 ppb A
Garden City 1.00 ppb C
Crocker Not detected B
Silver Lake Colony Not detected B
Raymond Not detected B
Showing 12 cities
No active violations Active violations

About Clark County Drinking Water

Clark County is served by 5 water systems covering 12 communities. No community here has an open violation on record.

Of the communities reporting lead results, 5 recorded a detection, with a median of 2.00 ppb — 13% of the federal action level. 7 reported none detected, which means below the laboratory limit rather than an absence of lead.

No community here has PFAS above the federal limit on record. State inspectors recorded no significant deficiencies.

Frequently Asked Questions

Is Clark County tap water safe to drink?▼
No community in Clark County has an open violation on record. No community has PFAS above the federal limit on record.
What is the lead level in Clark County?▼
Among communities with a detection the median is 2.00 ppb, 13% of the 15 ppb action level. 7 reported none detected and 0 reported no result.
How many water systems serve Clark County?▼
5 community water systems serve 12 communities here.
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