The Ten Mile River flows southwest for 7 miles (11 km) to the Pacific Ocean at the northern border of MacKerricher State Park, about 9 miles (15 km) north-northeast of the Noyo River at Fort Bragg and 5.7 miles (9.2 km) south of Westport, California. The river drains a watershed of approximately 76,800 acres (31,080 ha) in the California Coast Range. The mainstem begins at the confluence of the North Fork Ten Mile River and the Middle Fork Ten Mile River, each about 15 miles (24 km) long, originating at an elevation of about 2,400 feet (732 m). The name “Ten Mile” refers to the distance north from the Noyo River. The California Coast Range is primarily underlain by the Coastal Franciscan Complex. This consists of interbedded sandstone and argillite, with some pebble and conglomerate, and scarce amounts of limestone, chert, and basalt. These sedimentary rocks are mostly turbidites and other massive deposits, interpreted as ocean trench and trench-slope deposits from an east-dipping subduction zone along western North America during the Late Cretaceous and Early Paleogene periods. Along the California coast, up to four major phases of dune formation have occurred since the middle of the Pleistocene, roughly one million years ago, and continued until about 7,000 to 4,500 years ago. These ancient dunes have been buried by more recent formations. MacKerricher State Park includes approximately 1,300 acres (530 ha) of dunes that developed episodically about 1,500 years ago, 900 years ago, and 550 to 500 years ago. Coastal dunes generally form downwind of major river mouths, such as the Ten Mile River, which supply the sediments. The river’s connectivity to the ocean depends on flow discharge, a function of precipitation. Under low-flow conditions during prolonged droughts, sandbars build at the river mouth, often blocking it entirely. When this occurs, the estuarine portion of the Ten Mile River temporarily becomes a freshwater lagoon. Estuarine conditions return when large storms breach the sand barrier, re-establishing ocean connectivity. Despite episodic connectivity, the river and estuary provide important fish habitats for anadromous and marine species, varying seasonally and annually.

Tribes of the Pomo and Yuki peoples lived in or traveled through the Ten Mile River region, utilizing resources such as deer, fish, seaweed, shellfish, and acorns. The Pomo are descendants of Hokan-speaking people widely distributed along the California coast, centered at the Russian River. The Chedilna tribe of the Pomo had a village at the mouth of the Noyo River called Kadiu. Their houses were made from slabs of bark leaned together into cones 10 to 15 feet (3-4.5 m) in diameter. In 1855, an exploration party from the Bureau of Indian Affairs visited the area to find a site for a reservation. In the spring of 1856, the Mendocino Indian Reservation was established, stretching from the Ten Mile River in the north to the Noyo River in the south. The Pomo were the first to be forcibly moved to the reservation, followed by the Yuki, Wappo, and Whilkut. In 1857, Fort Bragg was established on the reservation to maintain order and subjugate the Native Americans. In 1862, U.S. Army troops were withdrawn to fight in the American Civil War, replaced by the California Infantry. In 1862, a mill worker named Duncan MacKerricher began assisting Indian Agent E.J. Whipple on the Mendocino Indian Reservation. Later that year, the Fort Bragg garrison was evacuated aboard the steamer Panama of the Pacific Mail Steamship Company, abandoning the military post. In 1864, the Native Americans there were forcibly removed to the Round Valley Reservation, then known as the Nome Cult Farm. The Mendocino Indian Reservation was discontinued in 1866, and the land was opened for settlement three years later. Duncan MacKerricher and his wife, Jessie, purchased an area of the former reservation known as El Rancho de la Laguna. They established a successful ranch that produced butter, grew potatoes, and was renowned for its draft horses. MacKerricher reportedly employed many Native Americans, including up to half the Pomo who had lived on the reservation. In 1949, their descendants sold the property to the state of California, and it became a state park that opened in 1952.

The Ten Mile River basin has been logged continuously since the early 1870s. Initially, trees were cut with single-bladed axes and dragged by oxen to mills in Fort Bragg. In 1883, a wharf was built at Laguna Point, about five miles (8 km) south of the river mouth, to load redwood lumber onto schooners bound for San Francisco. Ox teams were replaced by rail lines in the early 1900s, which were subsequently replaced by tractor roads in the 1930s. The California Forest Practice Act of 1973 banned destructive tractor logging on steeper slopes. The Georgia Pacific Company logged both sides of the river until 1999, when the Hawthorne Timber Company acquired the area. Historically, the Ten Mile River supported a significant coho salmon population. However, the spawning population declined from an estimated 6,000 fish in the early 1960s to between 14 and 250 in the 1990s. Contributing factors to this decline include natural variability, excessive sedimentation from logging, increased water temperatures due to the removal of riparian vegetation, and reduced woody debris in salmon habitats. Improved timber harvest practices and regular road maintenance have reduced sedimentation in about 45% of the watershed. In 2012, the California Fish and Game Commission designated the Ten Mile area as a marine protected area, marking the completion of the first statewide network of underwater parks in the United States. This marine reserve network now protects California’s coastal areas, benefiting important wildlife and habitats. It also supports the state’s tourism industry, including hotels and restaurants that rely on healthy fish populations. The Ten Mile River Estuary, Ten Mile Beach, and Ten Mile State Marine Reserve form a protected area of 10,050 acres (4,070 ha) extending 5 nautical miles (9 km) from the estuary out to sea. Read more here and here. Explore more of the Ten Mile River and MacKerricher State Park here: