Johnston Atoll

Johnston Atoll is an unincorporated territory of the United States located in the North Pacific Ocean.

It sits between the Marshall Islands and the Hawaiian Islands, southwest of the island of Hawaiʻi.

The atoll is under the jurisdiction of the United States Air Force (USAF). Because it is a restricted area, the public is not allowed to enter. Access for management requires a letter of authorization from the USAF. People also need a special use permit from the United States Fish and Wildlife Service (USFWS) to enter the surrounding waters. These waters are part of the Pacific Islands Heritage Marine National Monument and a National Wildlife Refuge.

The geography of the atoll is shaped by a coral reef platform. Originally, the atoll consisted of only two islands named Johnston and Sand Island. Over the 20th century, humans changed the shape of the land through coral dredging. This process of moving coral created two new artificial islands named Akau (North) and Hikina (East).

By 1964, these operations had significantly increased the size of the original islands. Johnston Island grew from 19 hectares to 241 hectares. Sand Island grew from 4 hectares to 9 hectares. The two new islands added 10 and 7 hectares respectively. This brought the total land area to 267 hectares.

The climate at Johnston Atoll is tropical but generally dry. It is classified as a hot semi-arid climate. The atoll receives just over 800 millimeters of annual rainfall. Consistent northeast trade winds blow across the area. There is very little seasonal variation in temperature. The terrain is mostly flat with an elevation ranging from sea level to Summit Peak. There are no natural freshwater resources on the islands. The vegetation is limited to some low-growing plants and palm trees.

The history of the atoll involves many different maritime and political shifts. The first Western record occurred in 1796 when the American brig Sally ran aground on a nearby shoal. In 1807, the islands were sighted by a Royal Navy ship commanded by Captain Charles James Johnston. The islands were later claimed by the United States under the Guano Islands Act of 1856. This act allowed citizens to claim uninhabited islands containing guano, which is used for fertilizer. In 1858, the Kingdom of Hawaii also attempted to claim the atoll, naming it "Kalama." However, the United States maintained sovereignty over the area.

Since 1934, the United States military has controlled the atoll. During this time, the site served many different purposes. It was used as a naval refueling depot and an airbase. The military also used the atoll as a testing site for biological and nuclear weapons.

It served as a secret missile base and a location for storing chemical weapons, including Agent Orange. These activities caused environmental contamination across the area. The USAF worked to remediate this contamination and completed the process in 2004. Today, the military performs only periodic monitoring of the site.

Despite its history of military use, the atoll supports significant marine and avian biodiversity. The surrounding waters host about 300 species of fish.

Green turtles and Hawaiian monk seals also visit the reefs. The area is recognized as an Important Bird Area by BirdLife International. The atoll holds the world's largest colony of red-tailed tropicbirds, with 10,800 nests recorded in 2020.

Many other species, such as the great frigatebird, also use the atoll for breeding.

Modern management focuses on protecting this delicate ecosystem from invasive species. In the 21st century, yellow crazy ants became a major ecological problem. These ants were killing the native seabirds. However, teams worked to manage the threat, and the ants were eradicated by the 2020s.

Today, USAF and USFWS teams continue to conduct environmental monitoring. They work to maintain the habitat and protect the native wildlife from further harm.