Streamflow Duration Assessment Method For Section 404 Compliance

Section 404 of the federal Clean Water Act and Oregon’s Removal-Fill Law require permits to protect water resources when someone plans to place soil, dredged or other material in regulated waters. The task of determining if a particular stream is protected under federal and state fill and disposal regulations has become a little easier. The new Streamflow Duration Assessment Method for Oregon will help natural resource professionals, consultants and regulators identify whether a fill or removal project with potential stream impacts must obtain permits.

This new method provides a consistent, repeatable and quick way to identify whether an Oregon stream is intermittent, perennial or ephemeral. Intermittent streams, which flow seasonally, and perennial streams, which flow continuously, are typically subject to both state and federal regulations. Ephemeral streams only flow after rainfall or during snowmelt, and under current agency practice are protected under the Clean Water Act if they have a significant effect on the integrity of larger downstream waters.

The tool was released in November after a two-year trial run. The method was tested and refined at over 170 sites in western and eastern Oregon during both the wet and dry seasons. The method proved accurate in many environments including natural, modified and braided channels. It is a scientific tool that is useful anytime the duration of streamflow must be determined, and may help identify other stream-related issues. Because of the demonstrated benefit in Oregon, the method is already being adapted for use in Idaho and Washington.

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address water quality standards, wastewater permitting and assessing potential impacts of chemicals in the aquatic environment.

Caltha LLP Aquatic Toxicology / WQ Standards Services Website

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

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address water quality standards, wastewater permitting and assessing potential impacts of chemicals in the aquatic environment.

Caltha LLP Aquatic Toxicology / WQ Standards Services Website