The National Environmental Policy Act of 1969 is the basic law governing federal reviews of construction projects’ environmental impacts. Unfortunately, it has evolved into an environmentally destructive monstrosity.
Why? Because the left-wing environmentalists have used it in endless litigation to oppose even projects that clearly would yield important environmental improvements over existing infrastructure.
New infrastructure is almost always significantly cleaner and safer than what it replaces. Even apart from the unavoidable physical depreciation of capital investments over time, technological improvements and other such advances enhance the environmental performance of new infrastructure projects relative to existing ones.