topped per second. Eventually, Hoover Dam was also forced to open its gates; its discharge peaked at per second and still caused downstream flooding. As inflow lessened at the end of the season, dam engineers were able to draw Lake Powell down below critical levels. Tunnel spillways seriously damaged Inspections of both spillways found severe damage. In the more badly damaged left spillway, inspection crews discovered a deep, wide, and long hole. Repairs and solutions After the flood, it was suggested that the flashboards atop the spillway gates should be replaced with stronger boards and kept permanently; this would allow an "insurance" against a 1983-reminiscent flood. Air slots added to tunnels Research by the Bureau of Reclamation found that an air slot at a specific point in each spillway tunnel would introduce air bubbles that would prevent cavitation and resultant shockwaves. Spillway upgrades and repairs commenced immediately after the 1983 floods receded and continued through the winter of 1983–84. Through the winter, heavy snowpack was reported in the upper Colorado basin. It was feared that this would produce a flood greater than the 1983 one, and as the spillway repairs continued, water was constantly released through the dam power plant and outlet works, a rate of roughly per second. 1984 floods possible The engineers allowed Lake Powell's level to fall to allow for the next winter's snowmelt. When the snowpack began to melt in spring of 1984, water levels reached several inches below the top of the flashboards in late June. As summer continued, inflows decreased and the reservoir level began to decrease. On August 12, 1984, construction teams completed repairs to the left spillway. It was tested at per second for several days. No noticeable damage was found in the spillways. Aftermath The 1983 flood, although it nearly caused a catastrophic disaster, was a "relatively small flood". It was, in fact, only a 25-year flood, or a flood that has a four percent chance of occurring in any given year. Impact of dam failure In 1990, the Bureau of Reclamation prepared a study of a Glen Canyon Dam failure. They predicted that if Lake Powell were at high pool, about of water would surge out of Lake Powell at an initial depth of over . Downstream communities and possibly every dam along the river, including Hoover Dam forming Lake Mead, Davis Dam forming Lake Mohave, Parker Dam forming Lake