Carquinez Strait Weighs In On a Dredged Future
Scientists, experts and indigenous voices speak up as the Trump administration proposes dredging environmentally sensitive habitat along the Strait.
- Deeper channels and wider berths are intended to bring bigger ships, clearing a path for CO2-intensive Canadian tar sands from Alberta to Bay Area refineries
- Considering the hazards of diluted bitumen, experts sort out when and where dredging is good or bad for San Francisco Bay — and what a major oil spill might look like
- Is California’s pledge for a carbon-neutral future under threat?
Life near San Francisco Bay Area surrounds us with this gem of nature that is the Bay itself. From almost anywhere, we can feel this inspiring connection to nature, by constantly being in its proximity.
Ohlone indigenous peoples once inhabited both sides of the Carquinez Strait — from Spanish, los Carquines refers to the Karkan-speaking tribes that thrived by fishing along the Strait’s rich banks for millennia.
I like to take my time when traveling through the Carquinez Strait, a 8-mile stretch of waterway near my home. This is where pure fresh water from the mountains of the high Sierras — the contents of all but one of a dozen major rivers flowing down from the Sierra Nevada range — meets and mixes with salt water from the San Francisco Bay and the vast Pacific Ocean.
I prefer rail. I love how close our train gets to the water’s edge, how it hugs the shoreline through tight curves around Point Pinole; how the rails zoom us underneath huge bridges and past busy, traffic-congested roadways, intimately bringing us up close to quiet, dockside communities like Crockett and Port Costa.
The train affords me an intimate experience with the landscape that would otherwise be missed by car.
The rails have become part of my own intimate connection to the nature of the Carquinez Strait — and my concern for its future.
And when I heard that the Trump administration wants to dredge this area to allow huge tar sands crude-carrying ships to refineries located along the Strait, I decided to take my own deep dive into the scale, scope and environmental impacts of this proposal — to both educate myself and help others learn more.
Scope of the Project — Dredging for deeper channels and wider berths
In April 2019, the Trump administration announced it was tasking the Army Corps of Engineers to dredge major sections of the Carquinez Strait.
Through a public comment period required by the Environmental Impact Study, the dredging plan raised concerns from a wide range of groups —from scientists and legal expert witnesses at the National Resource Defense Council, to local indigenous tribes, to kayakers and hikers who live near and enjoy the Strait’s environment.
The dredging plan’s focus is to deepen and widen what the Army Corps refers to as the Pinole Shoal. This is the shipping channel that arches eastward through San Pablo Bay and leads into the mouth of the Carquinez Strait to around Mare Island. Dredging along this stretch poses less concern, as dredging has occurred here regularly for years.
The plan also aims to deepen and widen the channel known as Bulls Head Reach, which extends about 2.9 miles from the Martinez-Benicia channel underneath the Benicia-Martinez Bridge and out to Port Chicago.
The biggest beneficiary of deep-water dredging: Refineries
Deepening and widening berths at refineries along the way, namely Phillips 66, NuStar Energy, Shell, Tesoro Amorco, Tesoro Avon and Valero — reveal the dredging plan’s main intent: to accommodate significantly larger ships, particularly tankers of the SUEZMAX and AFRAMAX class, which are among the world’s largest.
Dredging at these deep-water berths offers the lion’s share of the economic benefits of the project — estimated at more than $11 million per year. But environmental risks here pose special concerns, according to experts. Toxins located in sediments at these berths — the result of decades of waste dumping (both accidental and otherwise) — can be stirred up and could spill back into surrounding waters when dredging occurs.
A California Connection for Canadian Tar Sands
The Carquinez Strait holds particular significance in the global supply chain of crude oil today. Refineries that rim the Carquinez Strait could complete a vital link in a chain of connections to speed up processing for Canadian tar sands crude oil.
Beginning a multi-point journey from mines in Alberta province, tar sands crude undergoes a dilution process before being pumped through the Trans Mountain Pipeline and transported across British Columbia, ultimately boarding tankers at ports surrounding Vancouver.
The tar sands crude destined for the San Francisco Bay would journey by sea from ports in British Columbia, down the Pacific coast and into the Carquinez Strait. This approximately 4-day, 1,000-nautical mile sea lane journey represents one of the shortest hops available to the nearest cluster of large, high-capacity refineries anywhere on the U.S. West Coast.
Canada currently relies on refineries as far away as China and Southeast Asia to refine tar sands crude oil, a journey that adds days and additional costs for oil companies.
How Diluted Bitumen Differs from Conventional Crude Oil
Before Canadian tar sands can become useful as a petroleum product, it must undergo a refining process that converts the relatively solid, oily, gravel-like substance known as bitumen — which has the consistency of peanut butter — into a more liquid form. This refined liquid is called diluted bitumen, also known as dilbit.
Compared to conventional forms of crude oil, scientists know relatively little about the dangers of handling large amounts of diluted bitumen. We are only now learning about its potential impacts on human health and the environment.
Tar sands form the heaviest of crude oils —it is used to make asphalt — and was long believed to be too difficult to refine to make fuels. But advances in processing methods and hydraulic fracturing technology have resulted in an economic boom in tar sands extraction, especially for regions like Alberta, in recent years.
Dilbit is largely unregulated. And oil companies aren’t required to distinguish between dilbit and any other kind of petroleum product whenever they inform the public about what’s being pumped through pipelines or shipped on tankers.
What a diluted bitumen oil spill might look like in Carquinez Strait
On the foggy morning of November 7, 2007, the unthinkable happened on San Francisco Bay. A large container ship, the M/V Cosco Busan, struck one of the main footings of the San Francisco Bay Bridge, resulting in a 58,000-gallon oil spill involving thick bunker fuel.
The response by U.S. Coast Guard and local officials was quick but the tide soon shifted. And within 24 hours, the spill had spread throughout much of the Bay.
Scientists have learned some facts about what a major spill involving diluted bitumen looks like — based on extensive data from the Kalamazoo River oil spill in 2010, which involved a clean-up that took the Environmental Protection Agency over 7 years to complete. Still, experts cite the dire need for further study if we expect to understand all of the environmental hazards and what happens in a major dilbt spill, especially at sea.
A similar spill in Carquinez Strait involving diluted bitumen would be significantly worse than previous conventional oil spills, complicated by the much larger size of tankers, the unique tides, terrain and currents in the Strait, and especially the known hazards of dilbit on the environment and human health.
Once spilled, dilbit dynamically interacts with the environment, in ways scientists are only beginning to understand. The visual below represents how dilbit undergoes changes when exposed to the environment in a large spill.
Based on the latest models, scientists now have a better understanding of how dilbit sinks in water —after being spilled in a lake, stream or ocean. Exposure to sunlight evaporates lighter chemicals used to dilute bitumen. Wind and waves further cause the heavier bitumen to separate from these lighter chemicals, causing it to re-condense, coagulate and sink.
A Legacy of Sustainable Dredging in San Francisco Bay
Dredging has both benefits and environmental implications. Over a century of dredging in the Bay has taught us much about how to do it sustainably.
Along with ensuring good navigation and aiding commerce, dredging has helped the Bay’s natural processes that flush out slit and sand. For example, much of the coarse gravel from Bay dredging in deeper waters is used to make cement.
Clean mud and sand, the byproducts of sustainable dredging, can be re-used — to help maintain beaches and protect tide pools, marches and wetlands, which experts cite as vital to sustaining a healthy ecosystem for the Bay.
California’s Carbon-Neutral Pledge — Staying the Course
In 2018, California set the highest bar for the nation when then-Governor Jerry Brown committed to make the state a world leader to address climate change and become carbon-neutral by 2045.
The proposal to dredge Carquinez Strait for huge oils tankers threatens to take California backwards from this commitment, by increasing both CO2 greenhouse emissions and air pollution from local refineries.
Further Reading
The following are resources I have found particularly noteworthy on this topic and helpful in my research to write this article:
General Background Material — I found a number of background articles from reliable sources that served me well in my general research for this article:
“San Francisco Bay dredging fuels an unexpected concern: climate change,” San Francisco Chronicle, by Kurt Alexander, November 30, 2019
“The Army Corps Refinery Bailout Is Just What We Don’t Need,” National Resources Defense Council, by Ann Alexander, Senior Attorney, April 17, 2020
“U.S. Wants to Dredge San Francisco Bay to Aid Oil Shipping,” KQED Science Bureau, by Kevin Stark, June 27, 2019
“Environmental Groups Oppose Army Corps Plan to Dredge The Bay For Bigger Oil Tankers,” Bay Nature Magazine, by David Loeb, April 16, 2020
“SF Bay dredging project would increase oil shipments,” Sierra Club, by Jacob Klein, April 17, 2020
Source about Diluted Bitumen or “dilbit” — I learned a lot about dilbit and used the following reliable sources for my research. It is especially concerning how little we know about the environmental impacts of dilbit and the extent of damage that might occur in the event of a large-scale tar sands-based crude oil spill in San Francisco Bay:
Video: “The Kalamazoo River Oil Spill Disaster,” National Wildlife Federation Great Lakes, May 23, 2017
Video: “Seven Years and Counting: The Kalamazoo River Oil Spill Disaster,” National Wildlife Federation Great Lakes, June 9, 2017
“What is Diluted Bitumen And is it More Dangerous Than Conventional Oil?” — Tsleil-Waututh Nation Sacred Trust Initiative, June 7, 2019
“A Dilbit Primer: How It’s Different From Conventional Oil,” InsideClimate News, by Lisa Song, June 26, 2012
Notes: The diluted bitumen oil spill along the Kalamazoo River occurred in 2010. To date, it is one of the largest land-based oil spills to have ever occurred in the United States. It is also the only large oil spill involving diluted bitumen known to have occurred, providing scientists with a rare and invaluable opportunity to study and understand the dangers and environmental impacts of diluted bitumen.
In 2013, Science journalists at InsideClimate News were awarded the Pulitzer Prize for national reporting for their coverage of the Kalamazoo River oil spill. Their coverage is consolidated on their website, “The Dilbit Disaster Series,” and is included in their book, The Dilbit Disaster: Inside the Biggest Oil Spill You’ve Never Heard Of, 2016.
“Federal Regulations Should be Strengthened to Prepare for Potential Spills of Diluted Bitumen, Which Pose Unique Environmental Concerns,” The National Academies of Sciences, Engineering and Medicine, 2016
Considering what would happen in the event of a major oil spill involving diluted bitumen on San Francisco Bay and the Carquinez Strait — not much is known, and scientists have only begun to understand how diluted bitumen behaves in the environment. I did find a Canadian study that considered what a major dilbit spill would be like off the coast of British Columbia:
“Fate of diluted bitumen spilled in the coastal waters of British Columbia, Canada,” Marine Pollution Bulletin, Volume 150, January 2020
One way to picture what a major oil spill looks like on San Francisco Bay is to consider the M/V Cosco Busan bunker fuel spill of 2007.
A brief video featuring a visual simulation of the oil spill of the M/V Cosco Busan on San Francisco Bay, November 7, 2007 — Source: Tim Sinnott and Ocean Conservancy
Sources on Dredging in San Francisco Bay —some dredging is beneficial to wildlife habitats and people. Dredging unpolluted silt and sand helps clear clogged waterways and helps ensure habitat for some species of fish. Mud that’s dredged can be safely removed, relocated, and re-used to help restore marshes and wetlands around the Bay.
Other kinds of dredging can be harmful to Bay ecosystems and endangered species, especially where sediments contain toxins and when dredging churns up harmful pollutants.
“A Better Way to Dredge The Bay,” Baykeeper, by Sejal Choksi-Chugh, August 2015
“Advocating for Dredging Changes to Protect the Bay and Ocean Beach,” Baykeeper, June 3, 2015
I learned more — much more — about dredging in the San Francisco Bay when I read this simple yet highly informative and well-written blog post:
“Dredging for Sand in the San Francisco Bay,” San Francisco Natural History Series, by Adrian Cotter, August 29, 2015
California’s Carbon Neutral Pledge — since the signing of an executive order by then Governor Jerry Brown in 2018, California has set the highest bar and most ambitious goal yet of any state in the nation to address climate change.
“Can California Achieve a “Carbon Neutral” Economy?”, Scientific American, by Anne C. Mulkern of ClimateWire, September 12, 2018.
Getting Out and Getting Involved
Take a Hike: The Bay Trail offers plenty of hiking and pedestrian access along Carquinez Strait, featuring stunning vistas across two bridges — the Cariquinez and the Benicia-Martinez bridges.
Go By Train: Take any Capitol Corridor train from stops in the East Bay, such as Emeryville, Berkeley or Richmond. Hugging the water’s edge, trains travel the Carquinez shoreline and cross the Strait via the Benicia Martinez Rail Bridge.
Paddle Out By Kayak: Launching out of Benicia, Martinez, or Mare Island. Contact Bay Area Sea Kayakers.
By Direct Action: Stand.Earth and Protect The Bay Coalition represent indigenous tribal voices throughout the Carquinez Strait, serving as an advocacy group, direct action and community organizer, and resource for public comments on the dredging proposal.
