The Copper River and its tributaries make up an impressive watershed of wilderness. The Watershed encompasses 26,500 square miles and the the far corners of five distinct mountain ranges. These include the Alaska Range, the Wrangell Mountains, St. Elias Range, most of the Chugach Mountains and a small section of the Talkeetna Range. They contain sources of both volcanic and sedimentary rock from some of North America’s tallest peaks, as well the largest subpolar icefield in the world, the Bagley Icefield, making the Copper River Watershed one of the most prolific and diverse glacial deposits in the world. As the glaciers slide down the mountains into the valleys, they grind on the bedrock below, creating what scientists refer to as “glacial flour.” That sediment is a good source of iron and nutrients for phytoplankton and marine plants. These nutrients in turn support abundant wild salmon runs on the Copper River.

The Copper River drains glacial silt from along its entire path. During summer months, the daily sediment load can be 750,000 cubic feet of mud and sand. Much of the river is frozen in winter from late November to April. The Copper River carries one of the largest river sediment loads known and over thousands of years, the river has built up a layer of silt over 600 feet deep as it leaves the Chugach Mountains and enters the coastal plain. These depositions have formed the Copper River Delta.

The Copper River Delta

Mountainous glaciers blanketing the basin have been melting since the last ice age ended 12,000 years ago depositing massive amounts of glacial silt downstream, upwards of 60-100 million tons per year! The Copper River Delta coastal plain spans over 700,000 acres and stretches almost seventy-five miles along the coast.

The Copper River Delta is the northernmost portion of the Pacific temperate rainforest that spans from California to Alaska. It is the largest contiguous wetland on the Pacific coast of North America and is considered one of the most important fisheries and wildlife habitats in the world. The Copper River Delta is home to all five species of Pacific wild salmon, bears, wolves, nesting eagles and geese, trumpeter swans, moose, black-tail deer, mountain goats, lynx, countless other mammals and millions of migratory shorebirds. The Delta is almost completely contained in the Chugach National Forest. While the Copper River Delta is successfully managed by the Chugach National Forest for conservation of fish and wildlife habitat- for commercial, recreational and subsistence purposes- it is not permanently protected. The Copper River Watershed lacks a comprehensive management plan that would protect it from unsustainable development that has jeopardized many rivers in the Pacific Northwest. The importance of protecting this highly productive ecosystem is apparent.