Halibut Cove Lagoon is a semi‐enclosed embayment 0.7 miles (1 km) wide at the head of Halibut Cove on Kachemak Bay’s southeast shore, on the Kenai Peninsula, about 20 miles (32 km) northeast of Seldovia and 13 miles (21 km) southeast of Homer, Alaska. Named for Halibut Cove and first recorded by the US Geological Survey in 1961, the lagoon reaches depths of 230 feet (70 m). At low tide a gravel bar along an alluvial fan isolates the lagoon, narrowing its entrance to a swift, shallow stream; at high tide the channel is poorly defined, so local mariners exercise caution. A public dock at the lagoon’s south end serves boaters and water taxis ferrying visitors to roadless Kachemak Bay State Park. The south side of Kachemak Bay is of great interest to geologists because the bedrock is exposed, unlike the north side of the bay where most of the bedrock is buried under glacial till. Alaska’s gulf coast is underlain by two parallel accretionary terranes. The Wrangellia composite terrane—comprising the Peninsular, Wrangellia, and Alexander—and the Chugach-Prince William terrane have, for much of the Mesozoic, formed a magmatic arc and an accretionary wedge, respectively, above a circum-Pacific subduction zone. These terranes have shaped the region’s rugged landscape over millions of years. The bay’s south side, part of the Chugach-Prince William terrane, contains the McHugh Complex—a tectonic mélange of argillite, graywacke, chert (including radiolarian chert) and basalt. The lagoon’s western and eastern shorelines—except for the alluvial fan at Halibut Creek’s mouth—comprise basalt and chert, while its head is chiefly weakly metamorphosed siltstone, graywacke, arkose, and sandstone. Halibut Creek begins at the terminus of two unnamed cirque glaciers that once joined the Grewingk Glacier but are now isolated. The tributaries merge and flow about 8.5 miles (14 km) west-northwest to Halibut Cove. Their sediment, deposited during the recent glacial retreat, has formed a delta that restricts ocean circulation and influences local marine conditions.

Archaeological evidence shows that Kachemak Bay has been inhabited for about 3,000 years. The earliest settlers—known as the Kachemak Tradition—likely migrated from Kodiak, carrying tools and cultural traits similar to those of the Iñupiat. They lived in coastal settlements, hunting caribou, moose, bears and sea mammals while also catching fish, birds and mollusks. Discoveries include round or oval stone lamps, realistic carved stone figures and rock paintings of stylized men and animals. Although little is known about their earliest dwellings, later occupants built semi‐subterranean homes of stone and whale vertebrae. By about 1000 AD the Kachemak Tradition had abandoned the bay, its people replaced by ancestral Dena’ina Athabaskans. The Dena’ina—the only Northern Athabascan group to live on saltwater—adopted a sedentary lifestyle thanks to an abundant food supply. Archaeological work at the ancient village of Soonoondra near Halibut Cove suggests the Dena’ina have occupied Kachemak Bay for the past 1,000 years. In the bay, seals were the primary prey, while hunters also targeted sea lions, sea otters, porpoises, and beluga whales. The Dena’ina fished for salmon using weirs and dip nets, although most salmon were caught in streams and lakes. Deep‐sea fish—especially halibut and cod—were pursued, and long journeys were undertaken to harvest clams. In 1786 Grigory Shelikhov of the Shelikhov-Golikov Company dispatched a party under Vasilli Malakhov to attack the Kenai Peninsula Dena’ina in retaliation for their role in a battle on Shuyak Island in the Kodiak Archipelago. Malakhov established Alexander Redoubt in Kachemak Bay at present‐day Nanwalek. In 1789 Gerasim Izmailov entered Cook Inlet and explored Kachemak Bay; an island in Halibut Cove bears his name. In 1794 Russians attacked Soonoondra, abducting many young women and girls as wives. European diseases eventually decimated the Dena’ina, and cultural changes further reduced their population. The archaeological record and historical accounts reveal a long history of cultural resilience and change in Kachemak Bay, reflecting the region’s enduring strategic and ecological significance.

During the late 1800s and early 1900s, Dena’ina and Euro-Americans in Kachemak Bay fished Pacific herring for subsistence. Herring spawned in extensive eelgrass beds along the shores of Halibut Cove and Halibut Cove Lagoon, while Chinook salmon, beluga whales and harbor seals fed on them. In 1914, abundant herring spurred the first commercial fishery. The industry grew slowly until 1917, when the US government introduced Scotch curing—a new processing method. By 1918 the fishery boomed, with 36 herring salteries and reduction plants operating in Alaska, 15 in Kachemak Bay. Between 1919 and 1926 the number of plants in Lower Cook Inlet rose to 32, many based in Halibut Cove. The fishery collapsed in 1928 as herring numbers fell and salteries ceased operating. Overfishing and pollution of spawning areas—purse seines and gillnets catching fish before reproduction, combined with fish waste dumped on beaches—likely triggered a crash that proved both commercially and ecologically catastrophic. By 1930 the last herring plant had closed, and the fishery never recovered. Halibut Cove Lagoon and other shallow embayments once hosted extensive eelgrass beds that supported diverse marine life. Eelgrass produces oxygen, recycles nutrients, controls erosion and filters contaminants. In Alaska it is the preferred spawning substrate for Pacific herring and a rearing habitat for many commercial and forage fish during spring and summer. Steller sea lions, seals, porpoises, belugas and numerous bird species consumed large quantities of fish and eggs deposited on eelgrass. Discarded fish waste from salteries likely caused eutrophication in these poorly flushed embayments, ultimately destroying the eelgrass habitat. Read more here and here. Explore more of Halibut Cove Lagoon and Kachemak Bay here: