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The City of Portland, Oregon

Portland Water Bureau

From forest to faucet, we deliver the best drinking water in the world.

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FAQs about Groundwater Protection

Why is Groundwater Protection Important?
Over 70% of all Oregonians rely solely or in part on groundwater for drinking water.* Contaminated groundwater is very difficult and expensive to clean up – costing tens of millions of dollars. Implementing groundwater protection measures is the most cost-effective and responsible thing to do. Portland has a long commitment to source water protection and has had a groundwater protection program in place since 1988. The Columbia South Shore Well Field Groundwater Protection Program regulates businesses that use, store, and/or transport potentially hazardous chemicals in our groundwater protection area. Our motto is "A Drop of Prevention is Worth a Gallon of Cure." 

How Can I Help Protect Groundwater?
Businesses are not the only ones responsible for protecting groundwater. We all have a role in protecting this valuable resource whether at home, in the yard, or in your community.

Is my Business Regulated Under the Groundwater Protection Program?
If your business is located within the Columbia South Shore Well Field Wellhead Protection Area Boundary AND uses chemicals over set threshold amounts, you may be regulated under this program.

What Chemicals are Regulated?
The table below summarizes the types of chemicals and quantities of chemicals that are regulated under the groundwater protection program. Additional information on regulated chemicals and threshold quantities is available in Section 1 of the Reference Manual. Concentrations of the chemical must exceed 10% to be regulated. Because halogenated solvents pose the greatest risk to groundwater (due to their density and ability to travel easily through the ground) the threshold amount is only 10 gallons.  Products that contain halogenated solvents include industrial cleaners, glues and degreasers.

Regulated Chemicals and Chemical Quantities

Regulated Chemicals

Regulated Chemical Quantity Thresholds

Halogenated Solvents

10 gallons or 100 lbs.

Carcinogenic Materials

50 gallons or 400 lbs.

EPA’s “List of Lists” Substances

50 gallons or 400 lbs.

DEQ Hazardous Wastes

30 gallons or 220 lbs.

Petroleum Products (Reporting Only)

Petroleum-Based Liquid Fuels – 50 gal (required to report quantities only)

Petroleum-Based Liquid Fuels
(e.g., gasoline and diesel)

  50 gallons or 400 lbs 

What is the Protection Area Boundary?
The protection area boundary was developed using a sophisticated computer model that estimates how groundwater moves underground. A 30-year time of travel boundary was established to maximize the protection of groundwater. Thirty-year time of travel means that it would take 30 years for a drop of water to move from the protection area boundary to a drinking water well. The Portland Water Bureau also has an extensive monitoring well network to detect any potential threats to our drinking water wells.

What are the Groundwater Protection Program Requirements?
The requirements focus on spill prevention and containment, and rely on structural and operational best management practices. Businesses are also required to annually report their chemical use. All requirements are contained in the Reference Manual and are more broadly explained in the Program Implementation Guide.

Is Technical Assistance Available to Businesses?
Yes! Technical assistance is available to businesses and residents. The Portland Water Bureau, along with Gresham and Fairview, partners with the Columbia Corridor Association and the Columbia Slough Watershed Council to provide education and outreach.

*Groundwater Quality Protection in Oregon, Department of Environmental Quality, January 2011