Only because they tried to break through the police lines . Because they wanted to get emergency vehicles through . Now , IF there was a SIGNIFICANT chance of something bad happening , then I ' d be worried . I hear tornado sirens , I worry about a tornado . But I don ' t worry about tornadoes when it ' s bright and sunny out . If as many as 1 % of pipelines failed in the first decade , then I ' d be very concerned . But the chance is so small , I just don ' t see it worth worrying about . There are much more likely things to worry about . Like getting struck by lightning . That is assuming the one statistic you got from a propipeline website is correct . Like I said , a google search will turn up evidence to the contrary . Here is one result . oilpipelineleaks 20150522 story . htmlIf the first pipeline didn ' t leak using 30 year old technology , why the sudden HUGE concern that this one will ? ? Again , that ' s assuming there wasn ' t a protest over the first one . I haven ' t seen anything that says there was or wasn ' t , so it is almost irrelevant . Maybe the tribe didn ' t have the resources to battle it , maybe they didn ' t know its impact , maybe they did battle it and we never heard of it . There are lots of reasons . But that doesn ' t mean they should ignore this one if they have concerns . I mean , when Hitler had killed 1 million Jews , the rest of the world didn ' t go welp , the first million are down , guess we can ' t stop the rest from being killed . A bit of an extreme analogy , but I think it gets the point across .