Over-Water Oil Transfer Operations in Washington State

A major oil spill in our region would be devastating. So much is at risk—environmental, economic, and cultural resources, the endangered Southern Resident killer whales, and more. 

Transferring oil to and/or from vessels over the water is one of the ways that oil spills can occur. Friends is monitoring oil transfer operations in the Salish Sea. With data in hand, we are advocating for stronger oil spill prevention and mitigation requirements. 

According to the Department of Ecology, each year in Washington State there are “more than 10 billion gallons of oil moved through over 12,000 oil transfers. These activities create a risk for oil spills that are toxic and pose a significant risk to Washington’s environment, economy, public health, and historical and cultural resources.”1

Washington State requires advance notice of over-water oil transfer operations to help prepare for and prevent oil spills. The advance notice of transfer data is maintained in a spreadsheet and available to the public via a public records request. Friends has created an interactive tool to make some of this data easier for the public to learn about oil transfer operations that occur in Washington State. It is our hope that this tool will increase community engagement and advocacy for stronger environmental protections in rulemakings and other regulatory updates. 

Learn more about the visualized data and how to use this interactive tool via the Tool Guide below.

Tool Guide

The advance notice of transfer data in this tool is georeferenced to show where over-water oil transfer operations have occurred throughout Washington State. You can zoom in to any region or location on the map. Note that each time you select different data to be shown on the map (the year, transfer type, transfer rate, and/or product) the screen will revert to show the full Washington State map and you will need to zoom in to the region or location of interest again.

All the over-water oil transfer data shown on the map is color-coded to show whether the oil transfer operation was pre-boomed or not pre-boomed – see the Oil Spill Mitigation key to the right of the map. According to Ecology, “pre-booming oil transfers is the state’s first line of defense if a spill should happen.” Learn more about Washington State’s pre-booming requirements at Ecology’s pre-booming, alternative measures, and equivalent compliance webpage here.

More data is available by hovering your cursor over the “pre-boomed” and the “not pre-boomed” color-coded sections of each transfer location, including the location’s latitude and longitude, the total transfer amount in gallons, and the name of the oil transfer location.

Notes on Data Terminology (left hand column of the tool)

  • Date: Advance notice of over-water oil transfer operations were first reported in November, 2006. The Power BI includes the advance notice of transfer data through the second quarter of 2023, and will be updated annually.
  • Transfer Type:
    • Cargo is the oil products conveyed on ships
    • Fueling is the transfer of propulsion fuel to vessels; also called bunkering.
    • Lightering is “used to transfer cargo between vessels of different sizes like a barge and a bulker or oil tanker to reduce the vessel’s draft in order to enter port facilities.”2
    • Other transfers include lube oil/motor oil and hydraulic oil.
    • Vacuum is transfers conducted by a vacuum truck.
  • Transfer Rate: 
    • Rate A oil transfer operations have a transfer rate greater than 500 gallons per minute (GPM). Rate A transfers require pre-booming IF it’s “safe and effective” – a determination that’s based on the current and weather conditions. Highly volatile products such as gasoline are exempt from pre-booming requirements.
    • Rate B oil transfer operations have a transfer rate of 500 gallons per minute (GPM) or less. Pre-booming is not required for Rate B over-water oil transfer operations, though sometimes pre-booming of Rate B transfers does occur.
  • Product: Be sure to scroll down to see all 35 product types.
Suggestions for improvements and/or corrections to this tool are welcome! Please contact: 

Lovel Pratt
Marine Protection and Policy Director
Friends of the San Juans

12023-25 Budget Request — Operating, page 12, request #32. (2022). Washington State Department of Ecology.

2What is lightering? NOAA’s National Ocean Service, “Ocean Facts”.

Header Image:

 A barge delivers fuel to a bulk carrier vessel at anchor in Port Angeles, Washington. Source: Ecology Publication 06-08-035

I feel like I have found the home that I could not find anywhere else I have traveled and lived. Thank you, Friends of the San Juans, for protecting all of the islands and the Salish Sea.

Janet Burke

member, Henry Island