Humboldt Baykeeper: Humboldt Bay King Tides Photo Initiative in its Fourth Year

February, 2016


Humboldt Bay King Tides Photo Initiative in its Fourth Year
South I Street at the Arcata Marsh, 10-28-15. Photo: Saroj Gilbert.

Mad River Slough Bridge, Highway 255 in Manila, 12-24-15. Photo: Bernie Levy.

Graph of predicted and actual tide height, from 2012, Humboldt Baykeeper has led the Humboldt Bay King Tide Photo Initiative, which documents the highest tides of the year and allows us to envision how flooding from rising sea level will increasingly impact our beaches, shoreline, neighborhoods, and low-lying infrastructure such as roads, water and sewer pipelines, electric and gas transmission lines, and sewage treatment plants. Nearly 100 volunteers have taken thousands of photographs documenting the highest of high tides at dozens of locations around the bay. Thanks to funding from the Trees Foundation’s Cereus Fund and individual contributions, we have continued to lead this effort, compiling and mapping photos while building a long-term dataset.

King Tide photos from dozens of locations are posted on the Humboldt Bay King Tides Initiative’s Flickr page at

Map of King Tide photos on to El Niño and the unusually warm ocean conditions off of California, sea levels have been elevated, causing the King Tides (highest predicted tides caused by alignment of earth, moon and sun) to be extra high this winter, resulting in the highest sea levels ever recorded in the history of tide stations at the San Diego, La Jolla and Santa Barbara tide stations. The San Diego tide station has been recording sea levels since 1906, La Jolla since 1924 and Santa Barbara since 1974.

In the Humboldt Bay area, this year’s King Tides were nearly a foot higher than predicted in October, November, and December. On December 21, the actual high tide was more than one foot higher than predicted, as shown in the graph above  left.


New Zealand Mud Snail Discovered in Local Stream

The Humboldt Bay watershed’s first known occurrence of the invasive New Zealand mud snail was discovered by a student at Humboldt State University in a daylit section of creek on campus. They have previously been reported in Big Lagoon, Stone Lagoon, and Redwood Creek in Orick. The snails reproduce by the hundreds and pose threats to native species, including aquatic insects that are the primary food source for coho salmon, steelhead, and other threatened fish species.

There is no known method to eradicate the snail once it is introduced, so preventing its further spread is critical. Fishermen, researchers, and anyone else who frequently travels between riparian or aquatic locations should be sure not to spread the snails, which are small enough to go unnoticed on waders, bootlaces, and other gear. Thorough cleaning of gear followed by freezing or complete drying is the best way to ensure that you are not contributing to the New Zealand mud snail’s expansion into Humboldt territory.

You can help prevent the spread of this invasive aquatic snail by reporting suspected sightings to L. Breck McAlexander at the California Department of Fish & Wildlife’s Invasive Mussel Project in Redding via email:

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