Commission (FERC) urging federal officials to require that the dam's emergency spillway be armored with concrete, rather than remain as an earthen spillway, as it did not meet modern safety standards. "In the event of extreme rain and flooding, fast-rising water would overwhelm the main concrete spillway, then flow down the emergency spillway, and that could cause heavy erosion that would create flooding for communities downstream, but also could cause a failure, known as 'loss of crest control.'" FERC water agencies responsible for the cost of the upgrades said this was unnecessary and that concerns were overblown. In 2006, a senior civil engineer sent a memorandum to his managers stating, "The emergency spillway meets FERC’s engineering guidelines for an emergency spillway," and "The guidelines specify that during a rare flood event, it is acceptable for the emergency spillway to sustain significant damage." 2009 river valve accident At around 7:30am on July 22, 2009, several workers were deep below the reservoir operating flow controls to test a river valve chamber in the Oroville Dam. When the flow reached 85%, suction pulled a breakaway wall downstream into a diversion tunnel, cutting lights and nearly sending three workers to their deaths in the roaring current. One of the workers who was badly injured survived by clinging to a bent rail, where he was struck by tools and equipment being sucked into the tunnel. He was hospitalized for four days with head trauma, a broken leg and arm, cuts, and bruises. Cal OSHA concluded opening the valves without an energy-dispersion ring, which reportedly was absent, "created water flow with such great turbulence that it blocked an air vent and created a vacuum." The U. S. Occupational Safety and Health Administration sanctioned the DWR with six citations, including five classified as serious, and the department was initially fined $141,375. Two of the "serious" citations were overturned on appeal. This river valve system was one of the first parts of the dam to be built when the dam project started in 1961, because its initial purpose was to divert the river while the dam was under construction. After that, it served various purposes, including as a possible emergency release valve. Since the accident, DWR had implemented a standing order that prohibited the operation of the river outlet system and significantly limited access to the river valve chamber. Following the accident, DWR entered into a 2012 agreement