Eagle River Flats is a tidal flat and salt marsh of 2,471 acres (1,000 ha) at the mouth of Eagle River on Eagle Bay, which is on the eastern shore of Knik Arm in Joint Base Elmendorf–Richardson, about 10 miles (16 km) northeast of Anchorage and 7 miles (11 km) west of Eagle River, Alaska. The Denaʼina name for the river is ‘Yukla-hitna’ or Yukla Creek which translates to Eagle Creek according to the U.S. Geological Survey in 1898. In 1916, the Alaska Engineering Commission used the name Eagle River during the construction of the Alaska Railroad. The river starts at the terminus of Eagle Glacier and flows generally northwest for 22 miles (35 km) to the community of Eagle River, then about 10 miles (16 km) generally west to Eagle Bay. Eagle Bay is a shallow bight of Knik Arm about 4 miles (6 km) wide at the mouth. Knik Arm is a fjord extending north for about 34 miles (55 km) as the northern extension of Cook Inlet. Massive mountain ranges border Knik Arm, with the Chugach Mountains reaching elevations over 13,000 feet (3,962 m) to the east and south, and the Talkeetna Mountains to the north reaching elevations over 8,800 feet (2,680 m). The Knik and Matanuska Rivers are the two major tributaries discharging into Knik Arm. Both of these rivers are heavily laden with glacial silt which has contributed to the formation of the extensive tidal flats of the head of the fjord where the tidal range regularly exceeds 30 feet (9 m). The heavy silt content of the glacial rivers creates an unfavorable environment for marine invertebrates such as clams and mussels, but highly mobile or migratory marine mammals and fish are seasonally abundant. Five species of salmon spawn in the watersheds of Knik Arm, including Chinook salmon in the Matanuska River predominately in May and June, then followed by sockeye, chum, and pink salmon during the summer, with coho arriving in July in a run that usually lasts into September. Eulachons also spawn in the rivers of Knik Arm and harbor seals often follow the salmon and eulachon runs. Beluga whales have historically been observed in Eagle Bay between June and October chasing fish upstream from the river mouth. Eulachons were historically important to the Dena’ina for food, oil, and particularly for trade to tribes of the interior.

Knik Arm is the traditional territory of a Dena’ina subgroup called the K’enaht’ana who today reside at the villages of Eklutna and Knik. The K’enaht’ana traditionally lived in permanent winter vill­ages located along productive salmon streams, or by the mouths of lakes, and on the high bluffs above Knik Arm. Each village con­tained one or more multi-family dwellings which were organized on the basis of kinship. In addition to the villages, seasonal hunting and fishing camps such as at the mouth of Eagle River comprised a complex of satellite settlements. The annual round of subsistence activities began in spring after a period of relative food scarcity. Some people traveled to the mouth of Eagle River or farther to obtain eulachon, seal, and beluga. Geese and other migratory waterfowl were snared in the wetland marshes. After the river and lake ice melted, beavers were harpooned and the meat was smoked for preservation. Chinook salmon were especially significant because of their early arrival and large size. The primary method used to catch these fish were platforms called ‘tanik’edi’ made of wooden poles which extended over the water at the mouths of salmon streams. Individuals stood on these platforms and dip netted fish. Fish traps and weirs were constructed to catch smaller salmon. Village leaders supervised salmon harvests and regulated the distribution of the catch. Salmon were preserved by drying and smoking and stored in caches for use during the winter months. Other methods were also used such as fish might be buried in the ground to ferment in birch bark baskets. Hunting larger animals such as moose and sheep began in earnest in late summer and fall and just before freeze-up, hunters floated downstream in skin boats with their dry meat, dry fish, and skins to the winter villages. During the winter, people mostly stayed at their winter dwellings, subsisting on the stores of dry fish and meat. Visiting, trading, potlatching, and storytelling took place during these months. Small game, such as porcupine, hare, and ptarmigan were hunted with arrows, as well as snares, clubs, deadfalls, and pitfalls. Entire families obtained fresh fish by ice fishing in local lakes. Oral histories indicate that local food scarcity and starvation occurred during extended winters or when stored food supplies dwindled. This relatively difficult season ended with the return of waterfowl, eulachon, and salmon in spring when the annual cycle began again and continued for thousands of years.

The first documented European contact with the K’enaht’ana Dena’ina occurred in 1778 when Captain James Cook entered the inlet in search of the northwest passage, and he traded with the Dena’ina at Tyonek and Point Possession. A small boat party under the command of William Bligh explored Knik Arm but did not encounter any K’enaht’ana. By the 1780s, there were some Russians and creoles on the Kenai Peninsula but there is little evi­dence of any permanent occupation or formal exploration by Europeans in Knik Arm during the entire period of Russian colonization. It seems that the Russians had no direct control over the K’enaht’ana Dena’ina or their lands, although they did influence them by introducing western trade goods. The K’enaht’ana utilized their existing trading relation­ships to become middlemen between the Russians and interior Athabaskan tribes. The K’enaht’ana brought beaver, otter, fox, marten, and other land furs to the Russian post at Kenai and in return, received trade beads, copper, and iron utensils, clothing, tea, and sugar. However, contact with Europeans introduced diseases such as smallpox, influenza, measles, and tuberculosis which took a heavy toll on the Dena’ina, and many villages were depopulated. However, by the mid-1800s, one of the most enduring legacies of Russian colonization was the introduction of the Russian Orthodox Church to the Dena’ ina. Following the Alaska Purchase of 1867, demographic, economic, and social changes in Knik Arm occurred rapidly and brought an end to the rela­tive isolation of the K’enaht’ana. In 1894, a minor gold rush to Turnagain Arm brought thousands of people into the region. In 1910, plans for the Alaska Railroad developed, and the city of Anchorage was established. The K’enaht’ana engaged in seasonal wage labor in Anchorage and in the other settlements which sprang up along the railroad. They also found markets for their salmon catch at local canneries. In 1940, Fort Richardson was built northeast of Anchorage and extending to the coast of Knik Arm at Eagle River Flats. The post became the headquarters of the U.S. Army in Alaska, and initially had barracks for 500 soldiers, a rifle range, a few warehouses, a hospital, and bachelor officer quarters. Eagle River Flats was closed to subsistence hunting and fishing and has been continuously used since 1940 for heavy artillery training. In 1981, an unusually high number of duck carcasses was found in the wetlands and subsequent studies showed that the high mortality was caused by the ingestion of elemental white phosphorus, an extremely toxic substance. The primary source was smoke-producing shells detonated during training. White phosphorus particles were detected in near-surface sediments at multiple locations including the marsh and surrounding ponds where migratory waterfowl ingest them while feeding. As a result, the Army temporarily suspended bombing in the Eagle River Flats, and as the extent of the contamination became clear, the area was listed as a Superfund site. Following years of litigation, the Army was required to cleanup the chemicals, continue monitoring for additional pollutants, and initiate protective firing restrictions. Read more here and here. Explore more of Eagle River Flats here: