What site assessment activities will offshore wind developers perform as part of environmental review?

The Bureau of Ocean Energy Management (BOEM), the federal agency in charge of environmental review for offshore wind projects in the U.S. under the National Environmental Policy Act (NEPA), uses an unusual three-part process for environmental review. First, an Environmental Assessment (EA) is conducted for impacts related to site assessment activities — the studies done within the offshore lease area and along cable routes to identify sensitive habitats and species in federal waters, which are not well understood in our region. Then a programmatic Environmental Impact Statement (PEIS) will be completed that analyzes the cumulative environmental impacts from both the Humboldt and Morro Bay proposed offshore wind projects. Finally, each offshore wind energy area (WEA) leaseholder — RWE [1] and Vineyard Offshore [2] in Humboldt — will write individual Environmental Impact Statements (EIS) for each of their construction and operations plans.

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The Coastal Zone Management Act ​​(3) requires federal actions that may affect a State’s coast to be consistent with that State’s coastal management program; in California, that means the Coastal Commission can impose conditions on BOEM’s activities related to offshore wind. In April 2022, the Coastal Commission adopted seven conditions of approval for site assessment activities (4), as well as “reasonably foreseeable” future development, including a vessel speed limit of 10 knots (11.5 mph) and requirements for protected species observers onboard offshore wind-related vessels to decrease the likelihood of collisions with whales and other marine mammals. Other conditions address entanglement risk for marine mammals, sharks, and sea turtles; collision risk to seabirds; and impacts to corals, sponges, and other invertebrates on the seafloor. Further conditions require engagement with California Native American Tribes, environmental justice and local communities, and fishing communities.

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BOEM requires up to 5 years (5) of site assessment by offshore wind leaseholders prior to project design. First, the offshore wind companies submit (5) a site assessment plan (SAP) to BOEM for review.  BOEM will post final versions for RWE here (6) and for Vineyard Offshore here (7). To get a sense of what a final approved SAP looks like you can read the East Coast Vineyard Wind project’s SAP here (8).

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During site assessment, the leaseholders will be performing many different surveys in order to gather as much information as possible about the site area. These surveys consider everything from the ocean floor to the air above the turbines in order to understand, to the extent possible, the ecosystems in which the turbines would operate. Surveys will also consider potential transmission export cables from the turbines to shore. The developers and BOEM will use the survey data to develop an environmental baseline against which they can measure any potential impacts of the projects. Some of the characteristics surveyed include wind speeds, wave activity, geology, coastal habitats, water quality, benthic resources, fisheries and essential fish habitat, marine mammals and sea turtles, birds and bats, archaeological sites, social and economic resources, coastal and marine uses, and air quality.

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The first surveys developers will conduct are site characterization geophysical and geotechnical (i.e. imaging the seafloor and sediments) as well as metocean (i.e. measuring meteorological and oceanographic conditions) surveys to better understand the specifics of a site to inform project design decisions. Closer to (and after) construction, developers will conduct biological and environmental studies to better understand the wildlife, plants, and habitats specific to a site to be able to understand the potential positive and negative impacts of developing, constructing, and operating a project. Developers will also conduct desktop studies (i.e. socioeconomic analyses) to understand and describe the dynamics of how a project functions within a broader regional and community context.

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Off the coast of Humboldt, leaseholder-driven survey work began in federal waters in early 2024, while surveys in state waters (within 3 miles of the coast) will be done in the future. The AXYS Humboldt Project Buoy (9) is currently measuring wave and wind speed in the Humboldt Wind Energy Area (WEA) and will be doing so for the next several years. This information may help inform design of future wind energy projects in the Humboldt WEA.