The Army Corps of Engineers says the Los Angeles River is not "traditionally navigable." That may not surprise those who see it as a concrete flood control ditch. But to those who want to restore the river, it's an outrage. Other critics say the Corps' decision could lead to uncontrolled development as far upstream as Ventura County. North of Chatsworth, a rancher wanted to pave over some dry stream beds to build a road and control erosion. When there is water, the streams flow into the LA River, where the Army Corps of Engineers has jurisdiction under the Clean Water Act. When the rancher asked the Corps for guidance, it turned to a recent decision by the US Supreme Court.