LAUSR

Abstract The environmental impacts of energy generation plants, especially those with large dams, have been widely discussed in the Amazon region, but little attention has been paid to the impacts of the associated transmission lines. These impacts are likely to be substantial given the wide geographic extent of the lines and the relatively high forest cover in the traversed areas. Publicly available information about the location and extent of the transmission line network in the Amazon is neither accurate nor current, and its environmental impacts on terrestrial ecosystems have not been assessed on a large scale. This study estimates the scale of the impact of the current and planned transmission and distribution line network using a hand-digitized dataset and the predicted impact area determined from Environmental Impact Assessments. The Legal Amazon region contains 39,625 km of verified transmission and distribution lines, estimated to directly impact 23,467 km2 of land. We find that the transmission line network directly impacts double the area flooded by hydroelectric reservoirs in the Legal Amazon. Of the direct impact area, 5.1% is within protected areas and 10.3% overlaps with intact forest. By 2026, the transmission line network is estimated to grow by 37% in the Legal Amazon, increasing the direct impact to forests by 70% and to protected lands by 29%. Transmission lines are impacting enough land to be considered a serious conservation threat and should be treated as such in research and environmental planning in the Amazon region.