Humboldt Bay Complex

The Humboldt Bay WHSRN complex contains the largest bay between San Francisco and Coos Bay, Oregon and the delta wetlands of three rivers, the Eel, Elk, and Mad. There is a rich diversity of habitat types including invertebrate-rich tidal mudflats, eelgrass beds, salt marsh, estuarine, riverine, and palustrine wetlands, dunes, and seasonally flooded agricultural fields, which covers an area over 75 square miles (195 square kilometers). Eighteen square miles (47 square kilometers) has refuge status under the US Fish and Wildlife Service, California Department of Fish and Wildlife, or the cities of Arcata or Eureka. Other key landowners include the Bureau of Land Management, the Humboldt Bay Harbor, Recreation and Conservation District, and the cities of Arcata and Eureka. The eelgrass beds in the bay are the largest between Willapa Bay, WA, and Baja California, Mexico, and provide cover for many species of marine and estuarine vertebrates and invertebrates and food for hundreds of thousands of migrating shorebirds and waterfowl, especially Pacific Brant.

Most of South Humboldt Bay is under USFWS jurisdiction while areas around North Humboldt Bay are owned by California Department of Fish and Wildlife, City of Arcata, and USFWS. The Nature Conservancy has given their land to Humboldt Bay NWR. The central channel between the bays lies within the jurisdiction of the City of Eureka and is predominately industrial and urban. In 2004 the area was designated as an Important Bird Area by National Audubon Society.

Eureka continues to be a hub of commerce for the local area. The Old Town area has many beautiful Victorian homes and businesses including the world famous Carson Mansion. Timber industry is still very important to the area as well as fishing. The Port of Humboldt Bay is closer to Asia than Portland, Oregon, or San Francisco so there is pressure to entice trans-oceanic shippers to the area. While this would be a boon to the local economy, risks would come with more pressure for development and from exotic organisms that could be introduced into Humboldt Bay. The bay ecosystem was damaged by oil spills in 1997 and 1999, both related to port activities. Arcata Bay hosts one of the largest commercial oyster culture activities on the Pacific coast, which degrades habitat; there are currently proposals for expansion of this mariculture. Soil disturbance caused by logging, road building, and development on local watersheds continue to be a source of sedimentation and turbidity on Humboldt Bay. Climate change contributing to sea level rise will affect land usage and cause infrastructure changes.

Over 325 species of birds have been found within the Humboldt Bay Complex including over 31 species of waterfowl numbering approximately 70,000 throughout the winter. Approximately 50 species of shorebirds have been recorded locally, with 30-43 species in any month of the year. The highest shorebird diversity occurs during autumn migration (August – October). This site is the northernmost wintering area for significant numbers of American Avocets, Long-billed Curlews, Marbled Godwits, and Willets. Surveys in 2018 estimated that around 500,000 shorebirds migrate through the Humboldt Bay area during April and early May.

The proximity of Humboldt State University has produced an abundance of published research on diverse natural resource management topics. See the bibliography list below. Humboldt Bay is being considered for a National Estuarine Research Reserve. Humboldt Bay Harbor Recreation and Conservation District is completing a management plan for Humboldt Bay.

SACER (The scientific advisory committee for estuarine research) is a group of local scientists guiding restoration efforts within Humboldt Bay. Over 90% of bay wetlands (6000 acres) were diked and drained from the late 1800’s until the 1960’s. Restoring much of this acreage to productive wetlands will improve the health of the bay and is a goal of many local communities and area residents.