The Army effectively ended a standoff between Native Americans who opposed a planned pipeline that would cross their territory and the companies that want to build it. On Dec. 4, the Jo-Ellen Darcy, the assistant Army secretary for civil works, said the service would not approve of the plan to build the Dakota Access Pipeline under Lake Oahe in North Dakota. Members of the Rock Sioux Tribe had protested the plan, which would have placed the pipeline within half a mile of its reservation. The tribe contended that any leakages from the pipe could contaminate water supply, and the placement violated treaty rights. If it is ever built, the pipeline would connect oil production areas in Bakken and Three Forks, N.D., with a crude oil terminal in Pakota, Ill.