As modern rivers go, the Yellowstone is relatively
unadulterated. It's the longest dam-free river in the U.S.,
rushing 692 miles from its headwaters in Wyoming's Absaroka
Mountains through Yellowstone National Park and Montana's
Paradise Valley and eastern plains, to its confluence with the
Missouri. Cutthroat trout, vanished from much of their native
range, still hold on there. Before July 1, few people realized
that oil coursed through pipes a few feet below the riverbed.
Then, ExxonMobil's Silvertip pipeline failed, spewing an
estimated 42,000 gallons of crude just upstream of Billings.
It's too early to tell the extent of the damage, but birds and
other wildlife might be impacted by oil accumulations in
logjams, debris piles, riparian areas and quiet backwater
channels. Tom Livers, deputy director for the Montana Department
of Environmental Quality, says there's little precedent for
evaluating oil's impact on riverside hay crops, many of which
were soiled with crude spread by floodwaters. Fortunately, rob