Tutka Bay is a deglaciated fjord extending 8.5 miles (14 km) from Eldred Passage to the estuary of an unnamed river in Kachemak Bay State Park, about 18 miles (29 km) south-east of Homer and 15 miles (24 km) east of Seldovia, Alaska. The river starts from small remnants of the once great Southern Glacier and flows west-northwest for 7 miles (11 km) to Tutka Bay. Another tributary at the head of the bay on the northern shore cascades over a waterfall about 150 feet (46 m) high. This stream is fed mostly by a small watershed draining several perennial snowfields in the Kenai Mountains. The bay was named by William H. Dall, a cartographer, geologist and general scientist, during his visits to Kachemak Bay in 1880 (for the US Coast and Geodetic Survey), 1895 (for the US Geological Survey) and 1899 (on the Harriman Expedition). The name reportedly derives from the Dena’ina Athabascan word meaning “big enclosed water”. In 1891 about 4 miles of Tutka Bay was filled with ice from the Southern Glacier, which extended from 3,400 feet (1,036 m) in the Kenai Mountains to sea level in Kachemak Bay and to Port Dick in the Gulf of Alaska. The glacier has since nearly disappeared.

The southern Kenai Mountains are underlain by rocks of the McHugh Complex, consisting of graywacke and volcanic greenstones that developed during the Late Jurassic to Early Cretaceous (about 150 million to 140 million years ago) as ocean-trench turbidites and mélange sequences, subsequently thrust up as an accretionary wedge. Tectonic activity since the Wisconsin period (about 75,000 to 11,000 years ago) has caused as much as 330 feet (100 m) of subsidence. Present-day topography was shaped mostly during the Last Glacial Maximum, when the entire area was covered by an ice sheet that began retreating about 9,000 years ago, leaving remnant icefields at elevations from 3,000 feet (900 m) to 5,900 feet (1,800 m). The remaining ice persists mainly because of precipitation estimated at 10-33 feet (3-10 m) per year, intercepted from moisture-laden Pacific air masses moving eastward from the Gulf of Alaska. The archaeological record suggests humans have lived along the outer Kenai Peninsula coast for at least 7,500 years and occupied Kachemak Bay as early as 8,000 years ago. About 1,000 years ago Dena’ina Athabascan people migrated into Cook Inlet and Kachemak Bay from mountains to the west and north of the Kenai Peninsula. In the late 1800s Chugach Sugpiaq people moved from the outer coast and Prince William Sound to Kachemak Bay; their descendants still live in Seldovia, Nanwalek, and Port Graham.

In 1970 the Alaska legislature approved 105,387 acres (42,649 ha) of state lands to be designated as Kachemak Bay State Park. Two years later the legislature added nearly 200,000 acres (80,937 ha) of remote and rugged land and waters adjacent to the state park as Kachemak Bay State Wilderness Park. In 1974 the legislature established the Kachemak Bay Critical Habitat Area, which partially overlaps with the state park, to protect and preserve habitat crucial to the perpetuation of fish and wildlife. Within the boundaries of the state park and wilderness area are 201 privately owned parcels totaling approximately 845 acres (342 ha). Another seven parcels totaling 189 acres (77 ha) are owned by the University of Alaska, Bureau of Indian Affairs, Seldovia Native Association, and Bureau of Land Management. The park is mostly wild land; although a few cabins and semi-developed campgrounds exist, there is no road access and visitors normally fly in or travel by boat from Homer. Read more here and here. Explore more of Tutka Bay and Kachemak Bay State Park here: