The West Dock Causeway was constructed between 1974 and 1981 to support oil exploration and access a seawater treatment facility located 2.5 miles (4 km) into Prudhoe Bay, about 59 miles (95 km) northeast of Nuiqsut and 15 miles (24 km) north of Deadhorse, Alaska. The original structure was constructed in the winter of 1974-75 to serve as an alternative to East Dock.
In 1976, the original dock was extended to a total length of 1.5 miles (2.4 km) from shore and a depth of 6-7 feet (2 m). In 1981, another extension was built for the purpose of waterflooding the Prudhoe Bay oil field. This brought the total length of the causeway to 2.5 miles (4 km) reaching a depth of 12 feet (3.7 m). A bridge was built over a channel to allow for fish migration and small boat navigation.
Waterflooding or water injection is used by the oil industry to increase pressure in the oil field and thereby stimulate production. Water injection wells can be found both on and offshore to increase oil recovery from an existing reservoir. Water is injected to pressurize the reservoir and to push oil towards a well. Normally only 30% of oil in a reservoir can be extracted, but water injection increases that percentage and maintains the production rate of a reservoir over a longer period. In 1983, a mammoth barge-mounted seawater treatment plant was docked permanently at the end of West Dock. The facility is designed to treat up to 2 million barrels of seawater per day from the Beaufort Sea to boost the recovery of oil from the Prudhoe Bay field. Read more here and here. Explore more of West Dock here: