MacDonald Spit, Kasitsna Bay

MacDonald Spit, Kasitsna Bay

by | Sep 2, 2019

MacDonald Spit is about 1 mile (1.6 km) long and forms the northwestern edge of Kasitsna Bay on the Kenai Peninsula about 5 miles (8 km) northeast of Seldovia, Alaska. The local name was first published by the U.S. Geological Survey in 1951.

A spit or sandspit is a coastal depositional feature that projects into the sea and forms where longshore drift reaches a headland where the turn is greater than 30 degrees. Sediments that makeup spits come from a variety of sources including rivers and eroding bluffs. Longshore drift is the alongshore transport of these sediments by waves and ocean currents. For example, when waves break on a beach at an oblique angle, sediment is moved down the beach in a zigzag pattern. Finer sediments are transported higher and farther along the beach than coarser particles. Longshore drift is augmented by the strong tidal currents in Kachemak Bay which also transport sediment. Wave refraction can occur at the end of a spit, carrying sediment around the end to form a hook called a “recurved spit”, such as in Kasitsna Bay. A mudflat or salt marsh may form in the sheltered low energy zone behind the spit. MacDonald Spit it technically a tombolo that formed when the spit lengthened until it reached an island called Nubble Point, now linked to the mainland.

Since prehistory humans have inhabited spits for proximity to marine resources for exploitation. MacDonald Spit was probably first used as a summer camp by Alutiiq people and later by the Dena’ina to access fish and shellfish. A nearby village site on Yukon Island was investigated in depth by Frederica de Laguna in the 1930s, and a 1500-year chronology of use was assembled based on midden artifacts. In 1950s, Kasitsna Bay was homesteaded by the Ekren family who used a fish trap to catch salmon. In 1955, they started a cannery called the Ekren Packing Company to process clams, salmon, and Dungeness crabs. When fish traps were banned in 1959, they used gill nets and purse seines until the operation closed in 1975. Today, MacDonald Spit is subdivided into 36 lots mostly providing homes for a seasonal community and some residents still use set nets to catch salmon. Read more here and here. Explore more of MacDonald Spit here:

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About the background graphic

This ‘warming stripe’ graphic is a visual representation of the change in global temperature from 1850 (top) to 2021 (bottom). Each stripe represents the average global temperature for one year. The average temperature from 1971-2000 is set as the boundary between blue and red. The color scale goes from -0.7°C to +0.7°C. The data are from the UK Met Office HadCRUT4.6 dataset. 

Credit: Professor Ed Hawkins (University of Reading). Click here for more information about the #warmingstripes.

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