Cottonwood Creek is on the Kenai Peninsula in Kachemak Bay State Park and flows generally south for about 2 miles (3.2 km) to the northern shore of Kachemak Bay, about 13 miles (21 km) northeast of Homer and 6 miles (10 km) southwest of Voznesenka, Alaska. The creek was named after the common western black poplar or cottonwood tree in 1898 by William H. Dall of the U.S. Coast and Geodetic Survey. Quaternary gravels cover all of the Kenai Lowlands except an area in the Caribou Hills north of Kachemak Bay and the only known exposures of other rock formations are at sea cliffs and stream beds. The overlying gravels consist partly of glacial deposits such as till and other moraine material and partly of alluvial sands and gravels which are largely if not wholly of glacial derivation but which were deposited in their present position by waters that were not necessarily of glacial origin. Cottonwood Creek has incised these sediments to expose rocks from the Sterling Formation that dates from the Miocene to the Pliocene period. These rocks are weakly lithified interbedded sandstone, siltstone, mudstone, carbonaceous shale, lignite coal, and minor amounts of volcanic ash. The Sterling Formation is up to 10,000 feet (3,050 m) thick. The seacliffs at the mouth of Cottonwood Creek and canyon expose rocks from the Beluga Formation that dates to the Miocene. These rocks are similar to the Sterling Formation but the Beluga Formation is only about 5,000 feet (1,525 m) thick. The sea cliff at the mouth of Cottonwood Creek shows horizontal beds of shale and the remains of a bed of lignite about 30 feet (9 m) above high tide level that is 31 feet (9.5 m) thick and burned for 500 feet (152 m) along the bluff. The burning of the lignite probably occurred many centuries ago. Since thunderstorms are rare in this region, it is possible that climatic conditions have changed and that there were thunderstorms when the lignite bed was burned, or that the fire was caused by humans who lived on Kachemak Bay following the retreat of the glacier in Cook Inlet after the close of the Pleistocene.

Kachemak Bay has attracted human settlement for millennia due to its coastal location, diverse vegetation, relatively mild climate, and abundant marine and terrestrial wildlife. Archaeological evidence shows that ancestral peoples occupied Kachemak Bay as early as 8,000 years ago. These earliest inhabitants are unidentified culturally; however, archaeologists have identified in Kachemak Bay three other cultures called Ocean Bay, Arctic Small Tool tradition, and Kachemak tradition. Most ancestral peoples probably arrived by kayaks or larger umiaks from the Kodiak Archipelago, the Alaska Peninsula, Bristol Bay, and later from Prince William Sound, as evidenced by the types of materials they used and the styles of tools they created. About 1,000 years ago, Dena’ina Athabascan people migrated into Cook Inlet from the mountains to the west and north of the Kenai Peninsula. Kachemak Bay was the southernmost extension of Dena’ina territory where they gathered invertebrates, fished, and hunted marine mammals such as beluga whales, porpoises, and seals. Dena’ina people settled on a few islands along the southern shore of Kachemak Bay, and also at Bear Cove, Chugachik, and at the mouth of Cottonwood Creek, leaving middens and other indications of habitation. Kachemak Bay has long been of interest to archaeologists for providing an easily accessible and relatively dry window into the rich prehistoric past of the Gulf of Alaska. In 1883, Johan Jacobsen tested a village site in Kachemak Bay and described a clear separation between two distinct historical cultures. In 1930, Frederica de Laguna began archaeological research in Kachemak Bay which culminated with the publication of a monograph on Alaskan prehistory exploring the relationships over time between Alutiiq people and Dena’ina Athabaskan cultures. In 1974, William and Karen Workman began a long-term project in Kachemak Bay that resulted in major excavations at Cottonwood Creek and on Chugachik and Yukon Islands. The Workmans discovered archaeological evidence including hundreds of artifacts and several burials suggesting that the mouth of Cottonwood Creek was a village site used in the late winter and early spring when food resources were scarce and people were starving. Studies of human biology confirmed the identification of these as Alutiiq people, a culture that occupied the area for a span of at least 1500 years based on the midden remains of shellfish, harbor seals, and porpoises.

In 1970, the Alaska State Legislature approved 105,387 acres (42,650 ha) for designation as Kachemak Bay State Park, and two years later, added nearly 200,000 acres (80,940 ha) of remote and rugged land and waters for the creation of the Kachemak Bay State Wilderness Park. With subsequent additional land acquisitions, the two units presently encompass about 371,000 acres (150,138 ha). There is no road access to most areas of the park and visitors normally fly in with an air taxi or travel by boat from Homer. However, there are about 3,000 acres (1,214 ha) of parkland on the north side of Kachemak Bay that is accessible by road. These parcels are located at Diamond Creek, Overlook Park, Eveline, and lands surrounding Cottonwood and Eastland creeks. In 1989, land parcels in the Cottonwood-Eastland area that are accessible from East End Road on the north shore of Kachemak Bay were added to Kachemak Bay State Park. A small purchase of 153 acres (62 ha) in 1995 brought the total unit size to about 2,643 acres (1070 ha) with an estimated 4.9 miles (8 km) of shoreline. In 1993, the Kachemak Bay Critical Habitat Area was established to protect and preserve habitats especially crucial to the perpetuation of fish and wildlife. In 1999, the Kachemak Bay National Estuarine Research Reserve was established with no land acquisition but included 372,000 acres (150,543 ha) of terrestrial and marine habitats already designated as either State Park or Critical Habitat Area. The Reserve extends from the Fox River Flats at the head of the Bay, to Point Pogibshi on the southern entrance of the bay, to Anchor Point at the northern entrance of the bay. Read more here and here. Explore more of Cottonwood Creek and Kachemak Bay here: