Susitna River in the context of "Matanuska-Susitna Valley"

Gold was discovered in the Yentna-Cache Creek Mining District in the U.S. state of Alaska (also known separately as the Yentna District or Cache Creek District) of the upper Susitna River Valley in 1898, soon followed by claim staking. Placer mining was reported in the Cache Creek drainage of the Dutch Hills by 1906. Quaternary glaciofluvial deposits, alluvial deposits, and Cenozoic conglomeratic white quartz-breccia units have been mined in the Dutch Hills. About 200,000 oz (12,000 lb; 5,700 kg) of gold has been produced from these placer deposits.

By 1927, a road from Talkeetna was constructed into the mining area, known today as The Petersville Road. The mining camp of Petersville, Alaska served as the area Post Office for several years in the late 1920s and early 1930s. Two areas have been set aside for recreational gold mining, the North and South units of the Petersville State Recreation Mining Areas. Many smaller one-man and family placer mining operations continue today.

Cook Inlet (Tanaina: Tikahtnu; Sugpiaq: Cungaaciq) stretches 180 miles (290 km) from the Gulf of Alaska to Anchorage in south-central Alaska. Cook Inlet branches into the Knik Arm and Turnagain Arm at its northern end, almost surrounding Anchorage. On its southern end, it merges with the Shelikof Strait, Stevenson Entrance, Kennedy Entrance and Chugach Passage.

The Cook Inlet and both its arms are bodies of brackish water, containing a turbid mix of ocean salt-water and freshwater runoff from the various rivers and streams. The narrow channel of the inlet funnels the tides creating very fast-moving currents, rip tides, and occasional bore tides. Cook Inlet watershed is the most populated watershed in Alaska. The watershed covers about 100,000 km (39,000 sq mi) of southern Alaska, east of the Aleutian Range, south and east of the Alaska Range, receiving water from its tributaries, which include the Knik River, the Little Susitna River, the Susitna and Matanuska rivers, Eagle River, Ship Creek, Resurrection Creek, Portage Creek, Kenai River, and many others. The watershed includes the drainage areas of Denali and is the collection point for the runoff from many surrounding glaciers, leading to the high turbidity and large silt deposits. Within the watershed there are several national parks and the active volcano Mount Redoubt, along with three other historically active volcanoes. Cook Inlet provides navigable access to the port of Anchorage at the northern end, and to the smaller Homer port further south. Before the growth of Anchorage, Knik was the destination for most marine traffic in upper Cook Inlet. Approximately 400,000 people live within the Cook Inlet watershed.