The Keystone XL pipeline — the subject of a fierce political showdown over its environmental impact — got something less than a ringing endorsement from a State Department draft report on Friday. Construction of the controversial pipeline would substantially impact the environment, but it's also better than any of the alternatives, the report said, effectively giving the project the go-ahead. Environmental groups were quick to slam the report, which the Sierra Club called "deeply flawed," while Republicans in Washington welcomed it as proof the pipeline should get the green light. Still, the State Department's environmental statement is only a draft, not a final decision, and still faces a 45-day public comment period. A decision on the $5.3 billion, 875-mile pipeline has been held up for four years over concerns that it could threaten water and farmland and would be vulnerable to disastrous leaks — concerns the 2,000-page report conceded were possibilities. But the report found proposed alternatives were "not reasonable" and would have similar environmental impacts.