Douglas River flows north for 28 miles (45 km) on the Alaska Peninsula to extensive tidal flats in Kamishak Bay, about 108 miles (174 km) northeast of King Salmon and 89 miles (144 km) southwest of Homer, Alaska. The river starts at the terminus of an unnamed glacier at an elevation of about 1,000 feet (305 m) on the northwest flank of Fourpeaked Mountain in the Aleutian Range. The local name was reported in 1904 by George C. Martin of the US Geological Survey. It was also locally called Andrews River, and this is probably the same stream shown on Russian charts in 1852 as the “Chuyu River.”

The south coast of Kamishak Bay is characterized by extensive reefs exposed at low tide. These wave-cut platforms, along with elevated marine beach deposits onshore, indicate that this coast is rising. Material dated from Kamishak Bay suggests that the rate of uplift is about 1.5 feet (0.5 m) per century, partly in response to tectonic activity and possibly in part to isostatic adjustments following deglaciation. The wave-cut platforms on the south shore are completely exposed at low tide and are composed of sandstone strata of the Naknek Formation. A composite section from a nearby sea cliff suggests a thickness of about 2,000 feet (600 m).

Kamishak Bay also contains extensive deposits of estuarine silts from coastal rivers, exposed at low tide. The heads of most embayments are completely dry on minus tides, and the silt can be exposed for 3 to 6 miles (5–10 km) offshore. These estuarine silts are mostly an accumulation of rock flour carried into the bays by rivers and streams from melting glaciers, forming a veneer on the sandstone platforms. Read more here and here. Explore more of Douglas River and Kamishak Bay here: