Environmental assessment reform under the offshore wind power special act: changes and challenges

Impulsive noise generated during pile driving constitutes the most severe underwater acoustic threat in offshore wind construction. Underwater noise can propagate over tens of kilometers, and auditory injury to marine mammals has been documented within a few hundred meters of the pile-driving location, with behavioral disturbance occurring at ranges of several tens of kilometers (Madsen et al., 2006). Field measurements in Danish waters confirmed that impulsive noise poses an auditory injury risk to the protected harbor porpoise (Phocoena phocoena) population in Scotland’s Moray Firth at distances of approximately 100 m, and a behavioral disturbance risk at distances of up to 50 km (Thomsen et al., 2006). The intensity of impulsive noise varies substantially with monopile diameter and driving method; in current offshore wind projects using large monopiles exceeding 5 m in diameter, underwater sound pressure at a reference distance of 1 m can reach 240 dB re 1 μPa, a level capable of exceeding the marine mammal noise standard under South Korea’s Marine Environment Management Act (190 dB re 1 μPa) at distances of several tens of kilometers. Pile-driving noise can induce widespread behavioral and physiological effects across fish, marine mammals, and marine invertebrates, and low-frequency noise during long-term operational phases may also exert chronic effects on benthic ecosystems (Green et al., 2022). The near-total absence of systematic underwater noise assessment in South Korea’s former assessment framework is therefore a particularly serious concern in this context (Oh et al., 2021).

The effects of EMF generated by offshore wind farm submarine transmission cables on marine organisms have attracted growing attention in international research. In the vicinity of submarine cables, magnetic field intensity within 1 m typically reaches 0.1–5 mT (millitesla), a level sufficient to induce behavioral responses in marine species possessing electrosensory receptors, including fish, cephalopods, and crustaceans. It has been experimentally confirmed that EMF generated by high-voltage direct current submarine cables produces measurable behavioral effects on benthic cartilaginous fish possessing electrosensory receptors, specifically thornback rays (Leucoraja erinacea) (Hutchison et al., 2020). Research published in the ICES Journal of Marine Science has further reported that cable EMF may induce attraction behavior in the commercially important edible crab (Cancer pagurus) and potentially alter the composition and distribution patterns of benthic communities (Dannheim et al., 2020). A life cycle assessment-based synthesis analysis confirmed that EMF represents a major pathway through which offshore wind development can disrupt the foraging, orientation, and migratory behavior of fish and invertebrates (Li et al., 2023). South Korea’s West Sea coast encompasses major fishery grounds for electrically sensitive species such as common tonguefish and skates, making the potential consequences of EMF impacts on commercial fisheries a particular concern. Yet systematic assessment of EMF effects in South Korean environmental review has been virtually absent (Oh et al., 2021).

Bird collision and habitat disturbance rank among the most significant biodiversity impacts of offshore wind development. Analysis of 20 European offshore wind farms covering avoidance and collision responses across bird species found that reactions ranged from complete avoidance of the wind farm area to active attraction, with both habitat loss and collision mortality at levels that cannot be dismissed (Dierschke et al., 2016). Environmental assessment practice for offshore wind projects in UK waters established a system designating a broad list of vulnerable species—including northern gannets (Morus bassanus), duck species, and diving birds—as collision and disturbance sensitive, and mandating quantitative impact assessment for all such species (Bradbury et al., 2014). Post-commissioning monitoring at the Horns Rev offshore wind farm in Denmark documented large-scale avoidance behavior by scoters (Melanitta spp.) and other sea ducks, resulting in habitat fragmentation effects affecting hundreds of thousands of individuals (Dierschke et al., 2016). South Korea’s West and South Sea coasts lie along the globally significant East Asian–Australasian Flyway, with the primary staging and wintering areas of internationally protected species—including the Baikal teal (Anas formosa), bean goose (Anser fabalis), and oystercatcher (Haematopus ostralegus)—substantially overlapping with proposed offshore wind sites. Despite this, population-level quantitative assessment of bird collision risks was absent from domestic assessment practice under the former framework (Oh et al., 2021).

Analysis of the offshore wind siting conflict in Yeonggwang-gun, South Jeolla Province, through the lens of energy justice demonstrated that all four tenets of energy justice—distributional, procedural, recognition, and restorative—had been violated. The root causes of project failure were identified as the top-down pursuit of development without prior consultation with fishing communities and the absence of scientifically grounded compensation standards for fisheries impacts (Park et al., 2024). Analysis of the public dialogue process in a Tongyeong offshore wind case similarly found that participation in the siting decision process, adequate consideration of fisheries damages, and provision of sufficient information were the core determinants of community acceptance (Park et al., 2022). Research on public acceptance of a large-scale offshore wind project also confirmed that fishing communities’ concerns about economic losses and restrictions on access were the primary drivers of opposition (Kim et al., 2020). The structural roots of these conflicts lie in three deficiencies of the former environmental assessment system: (1) systematic analysis of the spatial overlap between fishing activity distributions and project areas was not required; (2) quantitative assessment of fisheries impacts and development of compensation standards were not mandated as assessment obligations; and (3) procedures guaranteeing meaningful participation by fishing communities in the permitting process were absent. It has been reported that such conflicts with fishing communities contributed to the withdrawal of major European offshore wind developers from the South Korean market, generating tangible adverse effects across the industry (Korea Times, 2024).

The substitution provision of Article 32(4) of the Enforcement Decree occupies the most central position among all contested environmental provisions of the Special Act. The impact of this provision’s operation on the substantive thoroughness of environmental assessment hinges on two critical conditions. First, the quality and duration of the government-conducted Preliminary Environmental Survey must genuinely approach the standard of a developer-led Detailed Assessment. Second, a supplementary survey mechanism must operate to systematically account for ecological changes between the preliminary and detailed assessment phases—particularly seasonal fluctuations and changes to the marine environment attributable to climate change.

It has been emphasized that baseline surveys of avifauna and marine mammals should be stipulated as a prerequisite for offshore wind project permitting, and that broad-scale strategic-level surveys can supplement but cannot substitute for project-level detailed assessments. In particular, because the spatial extent of potential biological effects from offshore wind projects may extend far beyond the development footprint, the spatial scope of baseline data collection should be determined independently at the project-level assessment stage (Bailey et al., 2014). This principle is operationalized in the EU SEA Directive (Directive 2001/42/EC) as the hierarchical linkage principle between strategic-level and project-level assessment, and requires that the categories and conditions for permissible substitution under Article 32(4) be rigorously specified through subordinate ministerial notice. The structural inadequacy of the 50% survey-period threshold is further demonstrated by the biological demands of migratory species assessment: Bailey et al. (2014) established that reliable population-level baseline data for migratory birds and marine mammals requires a minimum of two full annual cycles to capture seasonal variation, inter-annual fluctuation, and climate-driven distributional shifts. A preliminary survey satisfying only 50% of the standard two-year survey period—equivalent to approximately one year—may therefore systematically fail to capture entire seasonal migration windows, rendering the substituted data structurally insufficient for population-level collision risk modelling. Given that the Preliminary Zone designation may precede the Detailed Assessment stage by two to four years, the ecological conditions recorded in the preliminary survey cannot be assumed to remain representative at the time of project-level assessment, further undermining the scientific validity of unrestricted data substitution.

The restriction of avifaunal survey scope to “marine bird species” in the Annex to Article 4 of the Enforcement Ordinance, excluding migratory waterfowl such as Anatidae (ducks and geese) from mandatory detailed survey requirements, is at odds with the current trajectory of international offshore wind environmental assessment research. Anatidae species—including the mallard (Anas platyrhynchos), common pochard (Aythya ferina), common merganser (Mergus merganser), and greater scaup (Aythya marila)—are winter migratory birds whose movement corridors substantially overlap with proposed offshore wind sites along South Korea’s West and South Sea coasts, and are classified as species at elevated risk of turbine collision and habitat disturbance due to their offshore rafting behavior.

Large-scale avoidance behavior by scoters (Melanitta spp.) and other sea ducks at the Horns Rev offshore wind farm in Denmark has been documented, resulting in habitat fragmentation effects affecting hundreds of thousands of individuals (Dierschke et al., 2016). Analysis of 20 European offshore wind farms confirmed widespread avoidance responses among ducks and diving birds, with collision mortality at non-negligible levels in certain species (Dierschke et al., 2016). UK guidelines for avifaunal EIA in offshore wind projects have proposed a system classifying ducks and diving birds as explicitly identified vulnerable species and mandating quantitative impact assessment (Bradbury et al., 2014). Given these international research trends, the explicit exclusion of Anatidae from mandatory survey requirements in the Enforcement Ordinance is scientifically inadequate.

Article 34 of the Enforcement Decree exempts developers from the obligation to repeat Environmental Assessment when modifying turbine layout, foundation structure, or submarine cable routes following Development Zone designation, provided the modification is less than 30% of the originally approved design. The fundamental problem with this criterion is that the numerical threshold of 30% of design capacity fails entirely to reflect location-specific and qualitative changes in environmental impact. Offshore wind projects’ bird collision and habitat disturbance effects are more sensitive to changes in turbine position and ecological context than to absolute turbine numbers (Dierschke et al., 2016). A project of 100 MW (20 turbines of 5 MW each) could relocate up to six turbines without exceeding the 30% threshold, yet if the new turbine positions intersect a migratory flyway or encroach on a marine protected area boundary, the qualitative environmental impact would differ fundamentally. This asymmetry between volumetric and locational change is grounded in the ecological concept of sensitivity thresholds: within heterogeneous marine landscapes, small spatial displacements can produce disproportionately large ecological responses when they cross habitat boundaries or overlap with critical life-stage areas—such as migratory staging sites, foraging hotspots, or spawning grounds (Bailey et al., 2014; Dierschke et al., 2016). Marine ecological risk is therefore inherently spatial in character, and a purely quantitative capacity-ratio threshold is epistemologically ill-suited to capture this spatial dimension. This is precisely the principle that underpins the UK’s ‘Material Change’ standard, which determines reassessment obligations on the basis of substantive environmental impact change rather than modification volume—a regulatory philosophy that South Korea’s Article 34 has yet to incorporate.

Comparatively, the DEA conducted separate environmental reviews every time the designated area was adjusted—from 440 km² to 286 km²—during the Thor offshore wind farm SEA process (DEA, 2021). The UK’s “Material Change” standard is determined by whether the modification produces a substantive change in environmental impact, rather than by the volume of modification—a fundamentally different philosophical basis from South Korea’s Enforcement Decree Article 34, which relies on a simple capacity ratio. It has similarly been emphasized that in EIA frameworks for deep-water floating offshore wind facilities, reassessment obligations should be determined on the basis of whether the design modification produces a substantive change in environmental impact (Farr et al., 2021).

The Special Act and its subordinate legislation do not contain adequate specific mandatory provisions for post-commissioning environmental monitoring. The environmental impacts of offshore wind projects occur across the full project lifecycle—pre-construction, construction, operation, and decommissioning—and the magnitude of actual impacts cannot be ascertained without long-term operational-phase monitoring data (Bailey et al., 2014). The accumulation of operational-phase monitoring data is also emphasized as the evidence base for scientifically upgrading future project environmental assessment standards (Green et al., 2022). In Denmark and the United Kingdom, four-stage mandatory monitoring frameworks have been legally established, encompassing pre-construction baseline surveys, construction-phase noise monitoring, operational-phase monitoring of avifauna, marine mammals, and benthic ecosystems, and decommissioning-phase restoration monitoring (DEA, 2021). In contrast, post-commissioning monitoring under South Korea’s Special Act framework is largely implemented through Environmental Assessment consultation conditions rather than mandatory statutory obligations, with monitoring items, periodicity, and public disclosure requirements not specified in legislation—raising doubts about its effectiveness (Maeng et al., 2013).

Denmark mandates SEA at the plan level for offshore wind zone designation under the EU SEA Directive (Directive 2001/42/EC), operating a two-tier system hierarchically linking SEA to project-level EIA. During the Thor offshore wind farm (2020–2021) SEA process, the DEA reduced the initial candidate area from 440 km² to 286 km² through public consultation and stakeholder engagement, applying criteria for exclusion of areas of marine avifauna, marine mammal, and fisheries sensitivity (DEA, 2021). The Danish offshore wind potential screening and environmental mapping project launched in 2022, developed in collaboration with Aarhus University, DTU Vind, and GEUS, exemplifies an advanced approach to pre-identifying environmentally sensitive sea areas and incorporating them into long-term development roadmaps (DEA, 2024). The 2024 North Sea I zone plan notably operated a transparent SEA process that publicly disclosed minimum (5,000 MW) and maximum (17,445 MW) deployment scenarios based on environmental assessment results.

The core of Denmark’s SEA framework is that excluding environmentally sensitive sea areas at the broad plan level substantially simplifies the environmental issues requiring resolution at the project-level EIA stage—enabling shorter EIA processing periods while maintaining higher levels of environmental protection. This institutionally operationalizes the principle that strategic-level surveys complement rather than substitute for project-level detailed assessments, and represents a fundamentally different approach from the substitution provision of Article 32(4) of South Korea’s Enforcement Decree.

The United Kingdom has systematically conducted SEA for offshore energy development plans since 2001, completing 11 SEA studies by 2018. Additionally, through Habitat Regulations Assessment (HRA), quantitative assessment of bird collision and disturbance impacts is mandated for offshore wind projects that may affect Special Protection Areas (SPAs). The avifaunal impact assessment framework adopted by the UK Environment Agency provides for quantitative assessment of all vulnerable species, setting a broad list of collision-risk species including gannets, ducks, and diving birds (Bradbury et al., 2014). The UK’s “Material Change” standard, which determines reassessment obligations on the basis of substantive changes in environmental impact rather than the volume of modification, reflects a fundamentally different philosophy from South Korea’s Enforcement Decree Article 34, which determines obligations according to a simple capacity ratio (Dierschke et al., 2016).

South Korea’s integrated Environmental Assessment framework under the Offshore Wind Special Act shares the basic logic of the Danish and UK SEA concepts—namely the principle that broad-scale environmental screening at the plan level complements and streamlines environmental review at the project level. The critical distinction, however, lies in the difference between “substitution” and “complementation.” In advanced SEA frameworks, plan-level environmental assessment does not substitute for project-level detailed assessment; both tiers remain hierarchically linked while preserving their functional independence. By contrast, the special provision of Article 32(4) of the Enforcement Decree permits preliminary survey data to “substitute for” detailed assessment data, risking departure from this fundamental principle. The narrowing of avifaunal survey scope (excluding Anatidae), the exemption for modifications below 30%, and the insufficient mandatory monitoring obligations likewise represent elements lagging behind international standards.

The scope of permissible substitution under Article 32(4) of the Enforcement Decree should be strictly circumscribed, or the categories of permissible substitution should be specified through subordinate ministerial notice, to prevent the Detailed Assessment from becoming a formality. Concretely, items for which preliminary survey data may substitute should be limited to physical characteristics such as seabed topography, geology, and meteorological, hydraulic, and hydrological conditions, while biodiversity-related items—including avifauna, marine mammals, and benthic ecosystems—should be explicitly required to remain subject to developer-led detailed surveys. The broad-scale and project-level detailed surveys should be hierarchically linked while preserving their functional independence (Bailey et al., 2014).

The avifaunal survey items in the Annex to Article 4 of the Enforcement Ordinance should be expanded to encompass the full range of migratory waterfowl, including Anatidae, with standardized survey protocols developed to reflect seasonal movement corridors and offshore rafting behavior. Assessment methodology quantifying bird collision risks at the population level—including collision risk models—should be incorporated into assessment guidelines (Bradbury et al., 2014; Dierschke et al., 2016). Procedures for examining overlap with avian movement corridors at the Preliminary Zone selection stage should also be specified in Location Information Network operational guidelines.

The current 30% capacity threshold should be supplemented or replaced by qualitative environmental impact change criteria. Provisions should be added mandating Environmental Assessment regardless of modification magnitude for changes in proximity to ecologically sensitive elements such as protected species habitats, avian movement corridors, and marine protected area boundaries. A standard guideline for determining whether a modification produces a substantive change in environmental impact should be developed as a joint ministerial notice by the Ministry of Environment and Ministry of Oceans and Fisheries (Farr et al., 2021).

The composition standards for public-private consultative councils under Article 15 of the Enforcement Decree should be amended to guarantee the institutional participation of marine ecology specialists and representatives of environmental civil society. To institutionalize the recognition justice principle—that the voices of diverse stakeholders should be reflected equally in decision-making processes—the proportion of environmental expert participation and voting procedures should be explicitly specified in legislation (Park et al., 2022).

A four-stage post-commissioning monitoring framework spanning pre-construction, construction, operation, and decommissioning should be mandated in legislation, with periodic monitoring of bird collisions, marine mammal dynamics, benthic ecosystem changes, and underwater noise levels, alongside public disclosure obligations. The accumulation of operational-phase monitoring data constitutes the evidentiary basis for scientifically upgrading future project environmental assessment standards (Green et al., 2022). EMF monitoring in particular should be mandatorily incorporated from the early operational phase, given the uncertainties regarding benthic organism impacts identified in research (Dannheim et al., 2020; Hutchison et al., 2020). Monitoring results should be integrated into the Location Information Network for use as environmental screening data in subsequent Preliminary Zone designations.