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What are the development timelines for the proposed Humboldt offshore wind farm, marine terminal, and associated transmission infrastructure?

  • EPIC Staff
  • Sep 23, 2025
  • 3 min read

Updated: Apr 24


The Humboldt Bay Harbor, Recreation & Conservation District (Harbor District) began planning for its heavy lift marine terminal project in 2020 with a grant from the Headwaters Fund. It submitted its California Environmental Quality Act (CEQA) Notice of Preparatio (1) for the project on June 26, 2023. The Harbor District intends for environmental review and permitting to be completed in 2027 or 2028 (2). The Harbor District has also stated that it intends to begin work on mitigation for the project in 2027 and construction of the project itself in 2029. The timeline for the project as of March 2026 is available below.




The Humboldt Call Area was first identified in 2018 (3), BOEM executed the leases for the Humboldt Wind Energy Area (WEA) (4) in June 2023 (5). One of the developers began conducting a limited site assessment and surveys in 2024. However, because of the actions of the Trump Administration to stymie offshore wind development, neither of the offshore wind developers has conducted any new surveys or site preparation since his election.

Despite this pause, wind turbines could potentially start being constructed and installed in the mid 2030s. Once the wind turbines are installed and operational, they are expected to operate for at least 20 years. Turbines could then be replaced at the end of their lives. 



The process for permitting and constructing transmission lines is long and goes through multiples agencies. First, the California Energy Commission (CEC) determines how much electricity the State needs to meet load/demands in its Demand Forecast. In addition, they also analyze whether new energy sources, like offshore wind, are being built due to policy considerations. The CEC transmits those forecasts to the California Independent Systems Operator (CAISO) so that it can plan for where future transmission is needed. 


On May 6, 2024, the CEC published the Humboldt Wind Energy Area Transmission Corridor Evaluation: Volume 1: Report (9), prepared by Aspen Environmental Group. The report outlined several possible routes the transmission could take, as well as their risks. 


On May 23, 2024, CAISO provisionally approved (6) the transmission upgrades necessary to transmit the electricity generated by offshore wind to the greater California grid. Similar to the offshore wind lease areas, CAISO approves the right to bid for and begin studying the feasibility of transmission infrastructure, but final environmental review approval comes later and is handled by the California Public Utilities Commission (CPUC). In its provisionally approved plan (7), CAISO required that developers wishing to develop the new transmission demonstrate that it could be ready by June 1, 2034. CAISO opened the bid window for these projects on June 26, 2024 (12). CAISO also posted bid selection criteria and announced that they plan to choose a developer by spring 2025.

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On December 18, 2024, CASIO qualified three project sponsors (10) and proposals that satisfied all requirements to finance, construct, own, operate, and maintain the Humboldt Fern Road 500kV Transmission Line Project. The three qualified sponsors are listed as follows:

  • Horizon West Transmission, LCC (Horizon West) in Coordination with Pacific Gas and Electric Company (PG&E)

  • Cal Grid, LCC, and LS Power company (LSS Power (CAL GRID))

  • California Grid Holdings LCC (CalGrid/Viridion)

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In May 2025, (CAISO) selected Viridon to construct, operate, and maintain the Humboldt Fern Road 500kV transmission line (11). In that decision, Viridon agreed to build the transmission by June 1, 2034. ​​​​​​​​​See the transmission page for more information about their proposed project.


References​​

  1. Humboldt Bay Harbor, Recreation, and Conservation District. (2023, July 26). Notice of Preparation of Draft Environmental Impact Report. https://humboldtbay.org/sites/humboldtbay.org/files/WindTerminal_NOP_2023%200628_0.pdf 

  2. Humboldt Bay Harbor, Recreation, and Conservation District. (2024, April 2.) Request for Qualifications: Redwood Marine Offshore Wind and Heavy Lift Multipurpose Terminal: Final Permitting and 30% Design Project. https://humboldtbay.org/sites/humboldtbay.org/files/HBHRCD_MultipurposeTerminal-RFQ-PIDP23_v4.pdf 

  3. U.S. Bureau of Ocean Energy Management. (2018, November 1). Northern California Call Area. www.boem.gov/sites/default/files/renewable-energy-program/State-Activities/CA/Humboldt-Call-Area-Map.pdf 

  4. U.S. Bureau of Ocean Energy Management. (n.d.). Humboldt Wind Energy Area. www.boem.gov/renewable-energy/state-activities/humboldt-wind-energy-area

  5. California State Lands Commission. (2024). Offshore Wind Energy Development. www.slc.ca.gov/renewable-energy/offshore-wind-energy-development/ 

  6. Bureau of Safety and Environmental Enforcement. (n.d.). Renewable Energy. U.S. Department of the Interior. www.bsee.gov/about-bsee/renewable-energy 

  7. California Independent System Operator. (2023, January 16). 2023-2024 Transmission Planning Process. https://stakeholdercenter.caiso.com/RecurringStakeholderProcesses/2023-2024-Transmission-planning-process

  8. Natural Resources Defense Council. (2024, July 15). California Transmission Planning Ecosystem [slide deck]. 

  9. California Energy Commission. (2024, July 17). Transmission Corridor Evaluation Humboldt Wind Area Volume 1: Report (Revised) Prepared by Aspen. https://www.google.com/url?q=https://efiling.energy.ca.govGetDocument.aspxtn%3D257784%26DocumentContentId%3D93688&sa=D&source=docs&ust=1776978611819915&usg=AOvVaw1B37ItWlwrgE6VkFFP5dwl

  10. List of Qualified Applicants - New Humboldt Collinsville 500 KV Substation and Transmission Line Project. California ISO - 2023-2024 Transmission planning process. (2025, January 16). https://stakeholdercenter.caiso.com/RecurringStakeholderProcesses/2023-2024-Transmission-planning-process

  11. Caiso selects Viridon for major new transmission projects. Viridon. (2025, May 16). https://viridon.com/caiso/

  12. Baca-Chavez, A., et all. (2024, June 26). 2023-2024 Transmission Planning Process Phase 3 - Competitive Solicitation. California ISO. https://stakeholdercenter.caiso.com/InitiativeDocuments/2023%E2%80%932024-Transmission-Planning-Process-Phase-3-Competitive-Solicitation-jun-26-2024.pdf

© 2024 Environmental Protection Information Center / Humboldt Waterkeeper / Redwood CORE Hub / Blue Lake Rancheria.

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