Water stopped cascading down Oroville Dam’s fractured main spillway Monday, revealing a gaping wound from a beating that lasted nearly three weeks. Dam operators gradually scaled back water releases to zero over a six-hour period, providing breathing room for construction crews trying to clear debris from a badly choked Feather River channel and restart the dam’s critically needed hydroelectric plant. The shutdown is expected to last about a week, which the state Department of Water Resources hopes will be enough time to bring the plant back into operation.