Is Clark, SD Tap Water Safe? Quality & Contaminants

What was found in Clark's water

The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.

Contaminant	Level vs EPA limit	Suppliers	Source
Nitrate	500 µg/L 5% of the EPA limit 10000 µg/L Main supplier: CLARK RURAL WATER SYSTEM · 2,325 people · 2019 Highest in the city: 8800 µg/L — CLARK RURAL WATER-KAMPESKA · 602 people · 2019	2/3	SYR4
Copper	293 µg/L 23% of the EPA limit 1300 µg/L Main supplier: CLARK RURAL WATER SYSTEM · 2,325 people · 2019 Highest in the city: 1107.5 µg/L — CLARK RURAL WATER-KAMPESKA · 602 people · 2019	3/3	SYR4
Barium	8.6 µg/L 0.4% of the EPA limit 2000 µg/L Main supplier: CLARK RURAL WATER SYSTEM · 2,325 people · 2013 Highest in the city: 85.7 µg/L — CLARK RURAL WATER-KAMPESKA · 602 people · 2013	2/3	SYR4
TTHM	41.925 µg/L 52% of the EPA limit 80 µg/L Main supplier: CLARK RURAL WATER SYSTEM · 2,325 people · 2019 Highest in the city: 68 µg/L — CLARK RURAL WATER-KAMPESKA · 602 people · 2019	3/3	SYR4
Total Haloacetic Acids (HAA5)	14.35 µg/L 24% of the EPA limit 60 µg/L Main supplier: CLARK RURAL WATER SYSTEM · 2,325 people · 2019 Highest in the city: 22.62 µg/L — CLARK RURAL WATER-KAMPESKA · 602 people · 2019	3/3	SYR4
Lead	2.365 µg/L 16% of the EPA limit 15 µg/L Main supplier: CLARK RURAL WATER SYSTEM · 2,325 people · 2019 Highest in the city: 8.285 µg/L — CLARK RURAL WATER-KAMPESKA · 602 people · 2019	3/3	SYR4
Arsenic	2 µg/L 20% of the EPA limit 10 µg/L Main supplier: CLARK RURAL WATER SYSTEM · 2,325 people · 2013	2/3	SYR4
Selenium	0.7000 µg/L 1.4% of the EPA limit 50 µg/L Main supplier: CLARK RURAL WATER SYSTEM · 2,325 people · 2013 Highest in the city: 1.8 µg/L — CLARK RURAL WATER-KAMPESKA · 602 people · 2013	2/3	SYR4
Chromium	0.7000 µg/L 0.7% of the EPA limit 100 µg/L Main supplier: CLARK RURAL WATER SYSTEM · 2,325 people · 2013	2/3	SYR4
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: CLARK RURAL WATER SYSTEM · 2,325 people · 2025 Highest in the city: 0.0040 mg/L — CLARK · 1,148 people · 2023	3/3	LCR

Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of the system's samples — over 100% is worth reading, but is not by itself a violation. Formal violations are listed separately. These are the utilities' own EPA-reported results, not a city-wide average. A detection means the lab measured the substance — it isn't the same as exceeding a legal limit. Hover a source tag to see the EPA program and years behind each figure.

Water suppliers serving Clark

Supplier	Population served
CLARK RURAL WATER SYSTEM	2,325
CLARK	1,148
CLARK RURAL WATER-KAMPESKA	602

Frequently asked questions about Clark tap water

Is Clark tap water safe to drink?

EPA testing detected 10 contaminants in the water serving Clark. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.

How many water suppliers serve Clark?

3 public water suppliers report drinking-water monitoring for Clark, South Dakota to the EPA. Each is listed above with its population served.

What contaminants are in Clark's water?

The contaminants EPA monitoring detected in Clark include Nitrate, Copper, Barium, TTHM, Total Haloacetic Acids (HAA5). The full list, with the level at the main supplier and the data source, is in the table above.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.