Historic and active mines that may leach heavy metals like arsenic, lead, and cadmium.
Total Sites
65K
USGS MRDS
Search Radius
6.2 mi
Per-parcel proximity read
Agency
USGS
USGS MRDS
About This Database
- Formal Name
- Mining Sites
- Program
- USGS MRDS
- Maintaining Agency
- USGS
- Sites Tracked
- 64,741
What This Means for Growers
Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease. Metal contamination from mining follows a power-law decay with distance, meaning concentrations drop significantly but never reach zero. Acidic soil conditions (low pH) increase heavy metal bioavailability, making plants more likely to absorb them.
Smelter emission data from EPA studies shows measurable soil contamination extending 6+ mi downwind from large operations. For gardens near mining sites, a complete soil barrier (raised beds with imported soil over landscape fabric) is the most effective mitigation. Soil pH management (liming to raise pH above 6.5) reduces metal bioavailability in native soil.
Crop Risk Assessment
Root crops
Direct soil contact maximizes heavy metal uptake — carrots and potatoes are particularly efficient metal accumulators.
Leafy greens
Leafy greens accumulate cadmium and lead from contaminated soil, especially in acidic conditions.
Fruiting crops
Lower translocation to fruit, but soil contamination can still affect crop safety in highly contaminated areas.
Tree fruits
Deep roots and biological barriers reduce metal translocation to fruit; still test soil in mining districts.
Know Before You Grow — Mitigation Steps
- 1.Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
- 2.Use raised beds with imported clean soil and a complete geotextile barrier over native soil.
- 3.Lime acidic soils to raise pH above 6.5 — this reduces heavy metal bioavailability significantly.
- 4.Avoid using local stream water for irrigation in mining districts — test water sources for metals.
- 5.Historic mines (pre-1970s) often had no environmental controls — treat them with the same caution as active sites.
Top States for Mining
| State | Sites | Density |
|---|---|---|
| California | 8,329 | 0.05 |
| Arizona | 6,160 | 0.05 |
| Nevada | 6,064 | 0.06 |
| Alaska | 5,812 | 0.01 |
| Colorado | 5,049 | 0.05 |
| Missouri | 4,339 | 0.06 |
| Montana | 4,319 | 0.03 |
| Idaho | 3,980 | 0.05 |
| Washington | 3,881 | 0.06 |
| Utah | 3,654 | 0.04 |
| Oregon | 3,562 | 0.04 |
| New Mexico | 1,718 | 0.01 |
| Wisconsin | 1,087 | 0.02 |
| Virginia | 608 | 0.02 |
| Tennessee | 583 | 0.01 |
| Arkansas | 456 | 0.01 |
| Maine | 455 | 0.01 |
| North Carolina | 438 | 0.01 |
| Michigan | 435 | 0.01 |
| Texas | 369 | 0.00 |
Top Counties for Mining
| County | State | Sites | Density |
|---|---|---|---|
| Jasper | MO | 1,832 | 2.87 |
| Pima | AZ | 1,285 | 0.14 |
| San Bernardino | CA | 1,083 | 0.05 |
| Yavapai | AZ | 952 | 0.12 |
| Josephine | OR | 841 | 0.51 |
| Newton | MO | 822 | 1.32 |
| Inyo | CA | 811 | 0.08 |
| Elko | NV | 799 | 0.05 |
| Okanogan | WA | 762 | 0.14 |
| Shoshone | ID | 752 | 0.29 |
| Yukon-Koyukuk | AK | 732 | 0.01 |
| Stevens | WA | 729 | 0.29 |
| Nye | NV | 701 | 0.04 |
| Tooele | UT | 696 | 0.10 |
| Cochise | AZ | 694 | 0.11 |
| Jefferson | MT | 638 | 0.39 |
| Snohomish | WA | 594 | 0.28 |
| Pinal | AZ | 580 | 0.11 |
| Gunnison | CO | 544 | 0.17 |
| Blaine | ID | 542 | 0.21 |
Check Your Address for Mining
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