Full Breakdown
Humpback Whale Travels Deep into Sacramento-San Joaquin Delta
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Core Event
In mid-September 2026 an adult humpback whale, identified as CRC-11620, moved from San Francisco Bay into the Sacramento-San Joaquin Delta, reaching the Rio Vista Bridge area on the Sacramento River. The sighting was captured on video as the whale breached near the bridge. The Marine Mammal Center confirmed the animal’s presence and continues to monitor its movements.
Background & Context
Humpback whales occasionally appear far inland in the Delta. In 1985 a whale named Humphrey spent several weeks near Rio Vista before returning to the ocean, and in 2007 a mother-calf pair known as Delta and Dawn lingered in the Delta for about 20 days. These prior events illustrate that while rare, deep-Delta incursions are not unprecedented.
Data & Statistics
- Identification: CRC-11620, a well-known individual documented 15 times over the past 24 years in California and Mexico.
- Historical record: First recorded off California in 2002; most recent prior sighting was in Baja California in February 2026.
- Size: Humpback whales can reach up to 15 m (?49 ft) in length.
- Timeline (generalized):
- Early September – whale entered San Francisco Bay.
- Following days – traveled north past the Richmond-San Rafael Bridge and through the Carquinez Strait.
- Mid-September – U.S. Coast Guard reported the whale further up the Delta near Collinsville and Sherman Island.
- September 17, 2026 – latest confirmed location near Rio Vista.
On-the-Ground Reports
Local anglers reported the unexpected sighting. Another observer, Margaret Harlow, said the whale was heading southwest, away from the bridge. Witnesses expressed astonishment at seeing a whale “this far upstream.”
Official Statements & Responses
The Marine Mammal Center’s cetacean-conservation team is actively tracking the whale and coordinating with partners, including the U.S. Coast Guard. Kathi George, director of cetacean conservation biology, emphasized that the whale is in an “out-of-normal habitat area” and urged the public to maintain distance and avoid influencing its course. The Center advises anyone encountering the whale to give it space and let it decide its own movements.
Verbatim Quotes
- “While it's unknown whether this whale is just passing through or if there is an underlying, unknown ailment, the best thing people can do is experience this adult whale's presence from a respectful distance.” — The Marine Mammal Center
- “We were just flabbergasted that there was a whale this far upstream,” — Glover. After
- “Our team is actively monitoring the situation, and we kindly ask the public to please avoid changing the whale's course and let the animal decide where it wants to go,” — Kathi George, director of cetacean conservation biology at The Marine Mammal Center
- “This is a remarkable journey for a humpback whale,” — Kathi George, director of cetacean conservation biology at The Marine Mammal Center
What’s Next
The Marine Mammal Center will continue monitoring CRC-11620’s location and health status. The organization encourages the public to report any new sightings while keeping a respectful distance, and it remains prepared to coordinate with local authorities should the whale require assistance.