2008 Tanana Valley flood

A National Weather Service graph recorded the height of the Salcha River during the flood

By the evening of July 28, the record-breaking rainfall that had fallen to that point caused the National Weather Service to issue a flood warning for the tributaries of the Tanana River east of Fairbanks.[4] On the 29th, the continued rain forced the expansion of the flood warning to cover the entire Tanana and Salcha River basins between Salcha and Nenana, a stretch of land 320 miles (510 km) long.[11] The rising Salcha River forced home evacuations on the 29th and caused the Old Richardson Highway to be closed in several locations as the Salcha overflowed its banks and covered the road near the town of Salcha. An emergency shelter was set up to handle refugees from the Salcha River's flooding, and forecasters predicted the river would continue to rise.[11]

On the 30th, the Salcha River crested at 16.8 feet—almost three feet above flood stage—where it crosses the Richardson Highway.[12] This was the sixth-highest crest since measurements began in the first half of the 20th century. The last time the river reached that height was October 15, 2000, when the river crested at 16.91 feet (5.15 m).[13] More than 100 homes were at least partially underwater, and nearly two dozen Salcha town residents took advantage of the emergency shelter that had been set up at Salcha Elementary School the day before.[14]

High water remained in Salcha through the 31st, though the crest of the flooding had passed.[15] Water continued to cover roads in and around Salcha, and water-borne debris accumulated under several local bridges, causing impromptu dams.[15] By August 1, the Salcha River had begun to recede to a noticeable extent. Though some roads remained underwater and falling trees knocked out power to areas of the town, residents began to pump out basements and begin recovery efforts.[5] By early afternoon on the first, the Old Richardson Highway had been cleared of water and the National Weather Service canceled its flood warning for the Salcha area.[16]

The first effects of the flood began to be felt in Fairbanks late on the 29th, as the Tanana River overflowed its banks and covered low-lying areas of South Fairbanks. Thought was given on that date to closing the floodgates of the Moose Creek Dam, located on the Chena River as part of the Chena River Lakes Flood Control Project, but the Chena's rise was not as rapid as that of the Tanana, which lies to the south of the town, and no action was taken on the 29th.[11] Engineers also considered lowering the gates on the 30th, but the flow of the Chena River had not reached a level where computer models mandated the closing of the gates to protect Fairbanks.[14]

A Fairbanks shooting range is closed due to flooding.

The Tanana River, which is not controlled by the flood project, meanwhile reached a crest of 26.60 feet at Fairbanks on the 30th.[17] This amount was more than two feet above flood stage and was the highest level seen since August 1967, when the river crested at 27.80 feet (8.47 m) during the great 1967 Fairbanks flood.[18] The height of the water caused flooding in the Rosie Creek and Chena Pump neighborhoods west of Fairbanks, and caused some residents to evacuate. Residents who remained were placed under a boil-water order for fear that floodwater had contaminated the public drinking water system.[14] In response to the continuing spread of the flood, Fairbanks and Fairbanks North Star Borough authorities opened an emergency operations center to handle the response to the flood and answer residents' questions.[14] Residents of the Rosie Creek neighborhood were awakened in the early morning hours of the 31st by borough warnings and volunteer firefighters, who instructed them to evacuate. High water had surrounded the residents' homes, causing many to flee to a shelter set up at a nearby elementary school.[15] No residents were injured in the evacuation, something many of them credited to prompt and efficient warnings.[19] The continued high water of the Tanana River caused overflow to flood into the nearby Chena, normally a tributary of the Tanana. Despite that unusual flow, engineers at the Chena River Lakes Flood Control Project decided not to close the project's floodgates, forecasting that the Chena would not rise above flood stage, even with the increased flow.[5]

By the morning of August 1, the Tanana River had begun to fall in Fairbanks, just as the Salcha River had begun to recede in Salcha. Though isolated roads continued to wash out from heavy water flow and residents were not allowed to return to their homes, the water level of the river continued to fall.[5] Due to this fact, the opening of Fairbanks' Tanana Valley Fair—scheduled for August 1—was not delayed.[20] Despite the falling water level in the Tanana, the Chena River continued to rise due to the differing water levels in the two rivers. This fact caused the U.S. Army Corps of Engineers to close the floodgates of the Chena River Lakes Flood Control Project at 3:30 a.m. on August 1.[8] They remained closed throughout the day before being reopened at 5:30 a.m. on August 2.[21]

Though Nenana also received heavy rain from the storm system that began the flood, its position further downstream on the Tanana River meant that it did not receive the first effects of the flood until the 30th, when Alaska Railroad officials suspended operations south of Nenana due to track damage caused by rising water.[14]

The Tanana River overflows its banks during the flood.

On July 31, the Tanana River began to overflow its banks in Nenana. Water flooded the rails of the Alaska Railroad in town, caused an evacuation of the town's clinic, and flooded low-lying areas throughout the town.[5] By August 1, the entire town was at least partially flooded, with most basements and other low-lying areas being completely filled by floodwater. The flooding of the Alaska Railroad track in town forced a halt to all passenger and freight operations between Anchorage and Fairbanks, effectively cutting off Fairbanks from rail traffic.[8]

On August 2, the Tanana River at Nenana crested at 14.64 feet. This total was more than four feet above flood stage and was the third-highest water level ever recorded, falling short of a 15.9-foot mark in 1948 and the record 18.9-foot mark recorded during the flood of 1967.[22] The town shipyard was submerged under three feet of water, and the town's clinic was moved from its interim location in the fire station to the town airport after floodwater threatened the station. Town leaders encouraged residents to evacuate to higher ground until the flood receded.[21] Nenana High School was saved from flooding by just eight inches of elevation. Water lapped around the school's base, but did not enter the school itself due to that small margin.[23] High water lingered in the town until August 3, when a National Weather Service forecaster felt confident enough to say, "The worst is over."[24]