resident Donald Trump's proposed 250-foot triumphal arch will have "adverse" effects on dozens of historical landmarks, the National Park Service found. Nonetheless, the agency concluded in a report released Friday that the arch must stay at the proposed site on the banks of the Potomac River as the project is "inherently location dependent" and "not interchangeable" with any other placement. "A relocated arch elsewhere in Washington, D.C. or Virginia would constitute a materially different commemorative project," the report said. "For this reason, alternative locations outside Memorial Circle are not reasonable avoidance alternatives."