Revised Washington Benchmarks for Industrial Stormwater Discharge

Effective January 1, 20010, the Washington Department of Ecology has issued new benchmark concentrations for industrial stormwater discharges. Dischargers subject to the revised State industrial stormwater discharge permit must collect samples of stormwater discharge at least quarterly. Different levels of Corrective Action are required if dischargers exceed any of their respective benchmarks over one or more quarters.

The revised benchmarks are:

All Facilities:
Parameter Benchmark Value
Turbidity 25 NTU
pH Between 5.0 and 9.0
Oil Visible Sheen (Yes/No)
Total Copper Western WA: 14 ug/L, Eastern WA: 32 ug/L
Total Zinc 117 ug/L

Industrial Sector Specific Benchmarks:
Chemical and Allied Products ( SIC 28), Food and Kindred Products (SIC 20)
BOD5 30 mg/L
Nitrate/Nitrite 0.68 mg/L
Phosphorus 2.0 mg/L

Primary Metals (SIC 33), Metals Mining (SIC 10), Automobile Salvage and Scrap Recycling (5015 and 5093), Metals Fabricating (SIC 34)
Total Lead 81.6 ug/L
Total Petroleum Hydrocarbons 10 mg/L

Hazardous Waste Treatment, Storage and Disposal Facilities and Dangerous Waste Recyclers
COD 120 mg/L
Ammonia 2.1 mg/L
TSS 100 mg/L
Total Arsenic 150 ug/L
Total Cadmium 2.1 ug/L
Total Cyanide 22 ug/L
Total Lead 81.6 ug/L
Total Magnesium 64 ug/L
Total Mercury 1.4 ug/L
Total Selenium 5.0 ug/L
Total Silver 3.8 ug/L
Total Petroleum Hydrocarbons 10 mg/L

Air Transportation (SIC 45)
Ammonia 2.1 mg/L
BOD5 30 mg/L
COD 120 mg/L
Nitrate/Nitrite 0.68 mg/L

Timber Product Industry (SIC 24), Paper and Allied Products (SIC 26)
COD 120 mg/L
TSS 100 mg/L

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