单项选择题

It is hard to think of a major natural resource or pollution issue in North America today that does not affect rivers. Farm chemical runoff, industrial waste, urban storm sewers, sewage treatment, mining, logging, grazing, military bases, residential and business development, hydropower, loss of wetlands. The list goes on. Legislation like the Clear Water Act and Wild and Scenic Rivers Act have provided some protection, but threats continue.
The Environmental Protection Agency (EPA) reported yesterday that an assessment of 642000 miles of rivers and streams showed 34 percent in less than good condition. In a major study of the Clean Water Act, the Natural Resources Defense Council last fall reported that poison runoff impairs more than 125000 miles of rivers.
More recently, the NRDC and Izaak Walton League warned that pollution and loss of wetlands—made worse by last year’s flooding—is degrading the Mississippi River ecosystem. On Tuesday, the conservation group American Rivers issued its annual list of 10 "endangered" and 20 "threatened" rivers in 32 states, the District of Columbia, and Canada.
At the top of the list is the Clarks Fork of the Yellowstone River, where Canadian mining firms plan to build a 74-acre reservoir as part of a gold mine less than three miles from Yellowstone National Park. The reservoir would hold the runoff from the sulfuric acid used to extract gold from crushed rock.
"In the event this tailings pond failed, the impact to the greater Yellowstone ecosystem would be cataclysmic and the damage irreversible. " Sen. Max Baucus (D) of Montana, chairman of the Environment and Public Works Committee, wrote to Noranda Minerals Inc. , an owner of the "New World Mine. "
Last fall, an EPA official expressed concern about the mine and its potential impact, especially the plastic-lined storage reservoir. "I am unaware of any studies evaluating how a tailings pond could be maintained to ensure its structural integrity forever," said Stephen Hoffman, chief of the EPA’s Mining Waste Section. "It is my opinion that underwater disposal of tailings at New World may present a potentially significant threat to human health and the environment. "
The results of an environmental-impact statement, now being drafted by the forest Service and Montana Department of State Lands, could determine the mine’s future...
In its recent proposal to reauthorize the Clean Water Act, the Clinton administration noted "dramatically improved water quality since 1972," when the act was passed. But it also reported that 30 percent of rivers continue to be degraded, mainly by silt and nutrients from farm and urban runoff, combined sewer overflows, and municipal sewage. Bottom sediments are contaminated in more than 1000 waterways, the administration reported in releasing its proposal in January. Between 60 and 80 percent of riparian corridors (riverbank lands) have been degraded.
As with endangered species and their habitats in forests and deserts, the complexity of ecosystems is seen in rivers and the effects of development—beyond the obvious threats of industrial pollution, municipal waters, and in-stream diversions to slake the thirst of new communities in dry regions like the Southwest...
While there are many political hurdles ahead, reauthorization of the Clean Water Act this year holds promise for US fives. Rep. Norm Mineta (D) of California, who chairs the House committee overseeing the bill, calls it "probably the most important environmental legislation this congress will enact. \

The passage conveys the impression that ().

A. Canadians are disinterested in natural resources
B. private and public environmental groups abound
C. river banks are eroding
D. the majority of U. S. rivers are in poor condition

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