Bioregional & Watershed Profile

The Copper River Knowledge System presents data from Alaska’s Copper River and Bering Glacier watersheds, one of the mosaffordable essayst diverse system of interrelated environments throughout the Pacific Rim.

Glaciers and ice fields, alpine uplands, wide river valleys, ancient lakebeds, glacier fed rivers and rugged tectonic and volcanic mountains, boreal forests and coastal rainforests, river delta systems, fresh water lakes, glacier carved fjords, deep open ocean, the continental shelf and sand bars, fresh and saltwater marshes and shallow coastal waterways represent but a portion of the diverse systems that converge here; all within a 150 mile radius.

The Copper River is the center of this interdependent system.

The Copper River and Bering Glacier watershed is vast and sparsely populated. At over 27,275 square miles there are about 5.4 square miles for each of the 5,037 basin residents. Close to half of the population lives in Cordova (2,372), on the westernmost edge of the Copper River Delta area. In the upper Copper River basin there are 3 communities with populations over 350, and 11 smaller communities ranging in size from 44 to 192.

The Chugach Mountains are the natural divide between affordable essaythe upper and lower watershed. In the lower watershed, the Copper River Delta is coastal plane; river deltas, and glacial ice fields and is bordered by the Gulf of Alaska. The land area within the coastal region is over 5,000 square miles, including the near shore estuarine areas. There are no roads connecting the lower watershed to the “outside” world, and access is limited to boat or airplane. The upper watershed, the Copper River Basin, is over 22,000 square miles. It is the site of a large Pleistocene era lake, a flat and gently rolling plain, crossed by hundreds of streams and rivers, completely surrounded by high mountains, volcanoes, and more glaciers. Over six hundred miles of roads provide access to areas within the upper watershed and the outside world via the Alaska-Canada Highway.

The mainstem of the Copper River is almost 300 miles long, and carries the waters from ten other rivers that are each over 40 miles long. There are six lakes over 10 square miles in the drainage. Tazlina Lake is the largest lake within the watershed at 57 square miles. There are hundreds of smaller lakes and ponds scattered throught the entire basin. The Copper River system drains the south slope of the Alaska Range, the Wrangell Mountains, most of the Chugach Mountains, the Copper River basin, and a small section of the Talkeetna range. The source of Copper River is a small trickle that begins at Cooper Glacier on the north face of Mt. Wrangell, a peak of some 14,163 feet, located in the Wrangell-St.Elias National Park. Five major glaciers drain into the river, and from source to the sea the river falls nearly 3,600 feet in elevation, about 12 feet per mile, with an average current of seven miles per hour. The discharge is estimated at about 61,000 cubic feet per second, about 38 million-acre feet of water every day, although there is significant seasonal variation. Much of the river is frozen from late-November to April.

The fresh water and sediment load of the Copper River drives the near shore ocean environments along much of the northern coastline of the Gulf of Alaska. The Alaska Coastal Current mixes with the rivers fresh water outflow, and the current streams westward at Point Bentinct, the farthest point north on the Pacific Ocean. The near shore environment and associated Gulf of Alaska waters are a wealth of marine resources fed by ocean currents carrying a rich assortment of nutrients. These plankton rich waters serve as a transportation corridor and feeding grounds for immature salmon and a multitude of other species. Water depths vary within 20 miles of shore from shallow sandbars to about 50 fathoms (300 feet), then rapidly drop off to over 2,200 fathoms (13,200 feet).

The Copper River is the child of glaciers, ice ages, and changing world environments. The headlands of the the Copper River were snowfields, glaciers and rock tops 12,000 years ago, and the ice ran 300 miles south into the waters of the North Gulf of Alaska. Gradual global warming melted glacier ice and snow, then rain replaced snow in warmer months, and a great lake was formed in the Copper River Basin. The lake, known as Lake Ahtna, periodically filled and catastrophically drained over the next few thousand years. This glacial outburst flooding shaped the landscape from the Wrangell Mountains to the Copper River Delta and the near shore of the Gulf of Alaska. In the last 8000 years the river has built up a layer of silt over 600 feet deep by depositing over 75 million tons of sediment per year into the delta and the gulf. Based on a drainage area of about 24,600 square miles, or almost 16 million acres, this is one of the largest river sediment loads known. During the summer months the daily sediment load can be 750,000 cubic feet of mud and sand. These sediments have formed the Copper River Delta, the largest contiguous wetlands on the Pacific coast of North America. A dominant northwesterly ocean current carries sediment loads along the coast, forming barrier islands, behind which are semi-protected mudflats and grass banks.

© 2011 Copper River Knowledge System