Total Sites
33,912
9 federal databases
Severity Density
0.78
Severity-weighted sites per sq mi
High-Severity Sites
2,461
Superfund NPL, PFAS detections + similar top-tier records
Data Sources
EPA, USGS
9 databases checked
Source Breakdown
Top Counties in Washington
Kitsap County carries Washington's densest documented record — 4.40 severity-weighted sites per square mile across 1,100 records, most commonly Nitrate, including 20 high-severity sites. Density describes the county's record, not any single parcel.
| County | Sites | Density | Dominant Source |
|---|---|---|---|
| Kitsap | 1,100 | 4.40 | Nitrate |
| King | 6,301 | 3.77 | Underground Storage Tanks |
| Snohomish | 3,027 | 2.39 | Underground Storage Tanks |
| Clark | 1,068 | 2.26 | Underground Storage Tanks |
| Pierce | 2,734 | 2.23 | Underground Storage Tanks |
| Thurston | 1,042 | 2.16 | Underground Storage Tanks |
| Spokane | 2,118 | 1.69 | Underground Storage Tanks |
| Whatcom | 1,750 | 1.37 | Nitrate |
| Island | 197 | 1.35 | Underground Storage Tanks |
| Stevens | 1,287 | 1.17 | Mining |
Kitsap
Sites
1K
Density
4.4
Source
NitrateKing
Sites
6K
Density
3.8
Source
Underground Storage TanksSnohomish
Sites
3K
Density
2.4
Source
Underground Storage TanksClark
Sites
1K
Density
2.3
Source
Underground Storage TanksPierce
Sites
3K
Density
2.2
Source
Underground Storage TanksThurston
Sites
1K
Density
2.2
Source
Underground Storage TanksSpokane
Sites
2K
Density
1.7
Source
Underground Storage TanksWhatcom
Sites
2K
Density
1.4
Source
NitrateIsland
Sites
197
Density
1.3
Source
Underground Storage TanksStevens
Sites
1K
Density
1.2
Source
MiningAgricultural Pesticide Use in Washington
In the 2019 federal survey estimates, Washington's most-applied agricultural pesticides statewide were Glyphosate, 2,4-D and Chlorpyrifos. These estimates describe agricultural land use across the state — context for what's in use around the region, not a reading on any garden's soil.
Pesticide data: USGS NAWQA Pesticide National Synthesis Project (EPest county-level use estimates). Latest available county estimates: 2019.
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