Nushagak-Bristol Bay lowland, 23,600 mi2 (61,100 km2)
Land-surface form.--This province is a moraine- and outwash-mantled lowland that rises from sea level to an altitude of 300-500 ft (90-150 m), with a local relief of 50-250 ft (15-80 m). Drained by the Nushagak and other large rivers that flow into Bristol Bay, the lowland is dotted with morainal and thaw lakes.
Bering Tundra landscape of the Bristol Bay lowlands. (Photo: National Park Service.)
Climate.--This province has a marine phase of the tundra climate, with cold winters and cool, short summers. In the Koppen-Trewartha system, the marine tundra climate is not designated separately, but rather classified under tundra (Ft). But annual temperature ranges are much smaller in the marine phase than elsewhere in the tundra climate, winters are much milder, and annual precipitation is far greater (see Shear (1964) for further discussion). Daily winter lows average 5F (-15C) in the Nushaguk lowlands and 14F (-10C) along the Alaska Peninsula, and winter highs average around freezing throughout the region. Daily summer lows average just above freezing, with summer highs averaging around 64F (18C). Average annual precipitation is 13 to 34 in (330 to 870 mm).
Vegetation.--Moist and wet tundra communities provide the dominant vegetation. Standing water, mosses, sedges, and low-growing shrubs cover most of the area. Alder, willows, and scattered stands of stunted spruce and birch grow along the major rivers and streams.
Soil.--Dominant soils are Inceptisols. Most soils are formed in ash deposits of various thickness, underlain by gravelly glacial till, outwash deposits, or silty alluvium. Coastal plain soils are formed in gravelly alluvium, cinders, or weathered rock blanketed by thick sedge peat. Permafrost is sporadic or absent.
Fauna.--Brown bears are common mammals, partly because of large salmon runs in this area.
Bristol Bay provides staging and migration habitat for large numbers of waterfowl. Ospreys occur more frequently in this province than in any other part of Alaska. Blackpoll warblers are common breeders in conifer stands in the north.
Bristol Bay supports the largest run of sockeye salmon in the world.