Hardness
Very Hard
496 PPM · 29 GPG
Local water dashboard
Official source aggregationWater quality in Spearfish, SD 57783
A source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for Lawrence County.
1 active health-based violation
- Primary matched system
- Spearfish
- Source water
- Groundwater
- County
- Lawrence County
- Profile updated
At a glance
What the current records say
EPA quarter 2026Q2
Compliance screen
Review needed
1 active health-based record
Lead 90th percentile
0.001 mg/L
7% of action level
Utility match
10 systems
Serves 13,803 people system-wide
Hardness meter
How hard is the water?
Estimated local hardness
USGS hardness classification scale
496 PPM
Soft
0–59Moderate
60–120Hard
121–180Very hard
181+
0–59Moderate
60–120Hard
121–180Very hard
181+
Parts per million
496
mg/L as CaCO₃ equivalent
Grains per gallon
29
1 GPG ≈ 17.1 PPM
What this means at home
At 496 PPM, mineral scale can build up on fixtures and heating elements, reduce soap lather, and leave visible spotting. Hardness is primarily an aesthetic and appliance concern—not itself a tap-water safety rating.
USGS sites used
27
Nearest site
44.6 mi
Observation range
May 9, 2016–Nov 20, 2024
Estimate confidence
Low
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: 002N008E32AB Valve box on city water main (Well).USGS source documentation ↗
Regional context
Is 57783 typical?
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
Spearfish median
511 PPM
15 PPM lower2 indexed ZIP readings · Range 496–525.5 PPM
South Dakota median
516 PPM
20 PPM lower234 indexed ZIP readings · Range 20.5–1330 PPM
EPA benchmark screen
Contaminant snapshot
Available numerical results from associated SDWIS community water systems, compared with the applicable action level or federal MCL. Federal measured-value coverage is incomplete.
1 pass
Lead (PB90)
0.001 mg/L
Reported Dec 31, 2025
Copper (CU90)
Not available
No numerical 90th-percentile result
Numerical coverage
1 comparable result
Missing values remain blank; absence is not treated as a pass.
Lead (90th percentile)
Measured in mg/L
Local 0.001
EPA limit 0.015
Share of EPA benchmark
100% line = listed limit
2026Q2
- All records
- 19
- Health-based
- 4
- Active health-based
- 1
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| Public Notice | SD4602169 | Unaddressed | Dec 13, 2025 |
| Groundwater RuleHealth-based | SD4602169 | Unaddressed | Oct 31, 2025 |
| Consumer Confidence Rule | SD4602169 | Unaddressed | Jul 1, 2025 |
| Revised Total Coliform Rule | SD4602331 | Resolved | Mar 1, 2025through Mar 31, 2025 |
| Revised Total Coliform Rule | SD4602331 | Resolved | Feb 1, 2025through Feb 28, 2025 |
| LEAD AND COPPER RULE REVISIONS | SD4600316 | Resolved | Oct 17, 2024through Feb 11, 2025 |
| LEAD AND COPPER RULE REVISIONSHealth-based | SD4600316 | Resolved | Oct 17, 2024through Feb 11, 2025 |
| LEAD AND COPPER RULE REVISIONS | SD4600160 | Resolved | Oct 17, 2024through Feb 11, 2025 |
| LEAD AND COPPER RULE REVISIONSHealth-based | SD4600160 | Resolved | Oct 17, 2024through Feb 11, 2025 |
| Revised Total Coliform Rule | SD4600426 | Resolved | Oct 1, 2024through Oct 31, 2024 |
| Consumer Confidence Rule | SD4602169 | Unaddressed | Jul 1, 2024 |
| Chlorine | SD4600508 | Resolved | Jul 1, 2024through Sep 30, 2024 |
| Revised Total Coliform Rule | SD4600508 | Resolved | May 1, 2024through May 31, 2024 |
| Revised Total Coliform Rule | SD4600625 | Resolved | Feb 1, 2024through Feb 29, 2024 |
| Revised Total Coliform Rule | SD4600508 | Resolved | Feb 1, 2024through Feb 29, 2024 |
| Consumer Confidence Rule | SD4602169 | Unaddressed | Jul 1, 2023 |
| Revised Total Coliform Rule | SD4600314 | Resolved | Nov 1, 2021through Nov 30, 2021 |
| Stage 1 Disinfectants and Disinfection Byproducts RuleHealth-based | SD4600625 | Resolved | Oct 1, 2021through Feb 17, 2022 |
| Revised Total Coliform Rule | SD4600314 | Resolved | Oct 1, 2021through Oct 31, 2021 |
No reported violation does not prove that every contaminant was tested or absent; SDWIS measured values are incomplete and lag state records.
Solutions matcher
Your personalized water action plan
Matched to Spearfish ZIP 57783 using 496 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
High-Capacity Whole House Water Softener
496 PPM is 4× the high-hardness trigger used by this matcher.
Designed to reduce scale on fixtures, water heaters, glassware, and plumbing throughout the home.
Compare whole-house systemsDrinking water protection
Under-Sink Reverse Osmosis System
Groundwater Rule has a measured benchmark flag or active health-based SDWIS record in this profile.
A certified multi-stage RO system targets a broader range of dissolved contaminants at the kitchen tap.
Explore under-sink filtrationAffiliate disclosure: we may earn a commission from qualifying purchases, at no added cost to you. Product matching is educational and does not replace certified water testing.
Nearby indexed reports
Compare ZIPs in Spearfish
Estimates can differ across a city because monitoring locations and associated systems differ.
Frequently asked
Water questions for Spearfish
Is tap water safe in Spearfish?+
EPA ECHO reports 1 active health-based violation among the associated community water systems. Review the affected utility's current notice and Consumer Confidence Report.
How hard is the water?+
Nearby USGS observations produce an estimate of 496 PPM, or 29 grains per gallon, classified as very hard. This is not a household tap measurement.
Do I need a water softener?+
At 496 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.