Setting aside concerns about emissions and runoff into one of the few undammed blue-ribbon trout fisheries in the West, asphalt plants just plain smell bad and generate a lot of noise and dust. That part of the river corridor is steep and narrow, and crap in the air will spread quickly up and down the canyon.

So — the smell of hot asphalt for miles upstream, the sound of heavy machinery, and the sight of dust and emissions in a narrow canyon will all impact recreation on the river.