: HOME : ECOREGIONS : NORTHWEST COAST

Northwest Coast Ecoregion: Biodiversity

Map: WA Department of Natural Resources

Washington’s westernmost and wettest ecoregion extends from ocean depths to the Olympic Mountains’ glaciated peaks. Steller sea lions swim among the greatest number of kelp species in the world, and the endemic Olympic marmot burrows in alpine meadows.

Location

The Northwest Coast ecoregion fronts roughly 150 miles of ocean shoreline and encompasses roughly 11% of Washington State.

To the north, Cape Flattery is the continental United States’ most northwestern point. To the south, the mouth of the Columbia River marks the ecoregion’s southern border in Washington.

Inland lies a narrow band of coastal plain, the picturesque peaks of the Olympic Mountains, and the gentler Willapa Hills.

Like the state’s other ecoregions, the Northwest Coast extends into surrounding regions—north into British Columbia’s Vancouver Island and south along the Oregon coast.

Highway 101 winds north through communities like Ilwaco, Raymond, and Aberdeen-Hoquiam, the region’s most rapidly urbanizing area. It continues north through the timber town of Forks. At Forks, the highway turns east toward the town of Port Angeles and the Puget Trough.

Outstanding Biodiversity Features

• Geographic separation and unique species. Isolated by the Pacific Ocean, the Strait of Juan de Fuca, and the Puget Sound, a host of flora and fauna have evolved in this ecoregion. The Olympic Mountains offer the only home in the world to endemic rodents and trout and to rare plants, such as Olympic Mountain synthyris, Piper's bellflower, and Flett's violet.

• Tracts of verdant temperate rainforests. Some of the wettest places in the lower 48 are found here. Its rainforest of immense conifers drips with epiphytic ferns, mosses, and lichens. Scientists estimate that the world’s largest remaining stands of temperate rainforest, found within Olympic National Park, hold more living biomass than any tropical forest.

• Three vital estuaries for waterfowl, shorebirds, and anadromous fish. The Columbia River Estuary, largest in the Northwest, is critical for waterfowl, sea-run fish, and the endangered Columbia white-tailed deer. Willapa Bay is home to 47,000 acres of marsh, sandflats, and mudflats. Grays Harbor is both a vital nursery for young salmon and a stopover for tens of thousands of migrating shorebirds.

• Iconic marine species facing threats. Some of the most remarkable animals of the Northwest Coast—orcas, Steller sea lions, sea otters, loons, snowy plovers, and marbled murrelets—are species at risk.

Landforms

Dominating the Olympic Peninsula is the Olympic Range itself, a jumble of jagged peaks that reach nearly 8,000 feet. Distinct from the gentler coast ranges to the south and north, Olympics geology resulted from a subducting oceanic plate. This resulted in the uplift of sedimentary, volcanic, and metamorphic rock.

During the ice ages, a continental ice sheet flowed around the flanks of the Olympic Range. It created an outwash that isolated the mountainous peninsula from the Cascades. The advance and retreat of glaciers later sculpted the craggy peaks.

Photo: Washington Dept. of Natural Resources

Many rivers flow to the coast, including the Soleduck, Bogachiel, Hoh, Queets, Quinault, Humptulips, and Wynoochee. Between the peaks and shoreline, a coastal plain extends through much of the peninsula.

In contrast, the Willapa Hills to the south are a softer, more eroded landform. Their highest point barely tops 3,100 feet. The Chehalis River, the second largest river basin in the state, flows through the Willapa Hills and empties into Grays Harbor. During the Pleistocene, the Chehalis was a vast glacial river that drained the Puget Trough.

In addition to miles of ocean shoreline, the coast counts three important estuaries, the Columbia River, Willapa Bay, and Grays Harbor.

Climate

Rainy is the word along the Northwest Coast. The maritime climate means mild temperatures, frequently overcast days, and lots of precipitation. The Olympic Mountains catch much of the ecoregion’s rainfall.

Mt. Olympus itself receives 220 inches annually, much of that as snow. The rain shadow region on the eastside of the Olympic Peninsula captures only a fraction, roughly 20 inches.

Overall, precipitation ranges from 60 to 240 inches, much of it falling in the late fall to early spring. In the higher peaks of the Olympics, heavy snowfall—up to ten feet—is frequent.

In the coastal valleys, summer fog and cool temperatures are common. The annual climate statistics for Aberdeen are illustrative: an average high temperature of 58 degrees, a low of 42, and about 84 inches of precipitation, most of it rain.

Marine Environment and Species

Photo: NOAA

The Northwest Coast includes a wide range of marine environments. The coast’s kelp beds help protect beaches from wave erosion and offer habitat for fish like the striped sea perch and mammals like the reintroduced sea otter.

The rocky coastline provides tidepool habitat for a rich fauna of invertebrate sea creatures, among them urchins, stars, and cucumbers. The region’s tidewaters provide a vital migratory stop for shorebirds. Most the rivers in the ecoregion still support salmon runs.

The National Marine Sanctuary website describes other marine habitats along our coast. Much of the coastal area is included in the Olympic Coast National Marine Sanctuary.

Among those mammals most commonly associated with the ecoregion are Steller sea lions, Pacific harbor porpoises, and orcas. Birds include marbled murrelets, black oystercatchers, and tufted puffins.

Vegetation

Photo: Olympic National Park

The western edge of the Northwest Coast is the nation’s greatest example of temperate rainforest. High rainfall—more than a dozen feet on average—and mild temperatures have made these coniferous forests some of the planet’s most productive.

Trees grow big here. In the protected area of Olympic National Park, Sitka spruce and western hemlocks can top 300 feet in height and more than 20 feet in girth. Western red cedar and Douglas-fir also join the closed canopy. The rainforest offers ideal habitat for a variety of epiphytic ferns, mosses, and lichens.

In the alpine heights of the Olympic Mountains, wildflowers grow abundantly through their short season. Meadows of Sitka valerian and lupine contrast with scree slopes dotted with cushion plants. These mountains are the only place in the world where Olympic Mountain synthyris, Piper's bellflower, and Flett's violet grow wild.

Marshes, fens, ponds, and seasonal wet meadows, along with riparian and herbaceous wetlands, each host their own suite of plants and animals. Trees like black cottonwood, big leaf maple, red alder, and Oregon ash grow in moist ground, accompanied by thickets of willow and Pacific ninebark.

Terrestrial Wildlife

In the Northwest Coast ecoregion’s protected heights, the endemic Olympic marmot lives in alpine meadows. On lower slopes the Roosevelt Elk, considerably darker and larger than its Rocky Mountain cousin, lives in the old-growth rainforest. It is joined there by black bear, black-tailed deer, and the Northern spotted owl.

The ecoregion’s wetlands offer habitats for a wealth of species including the trumpeter swan, Van Dyke’s salamander, the Olympic mudminnow, and the Makah copper butterfly.

On the ecoregion’s southern edge, the Columbia white-tailed deer is on the endangered list. Other mammals considered of greatest conservation concern include the bat, Keen’s myotis, the Mazama pocket gopher, and the marten.

People in the Ecoregion

Indigenous peoples have long made their home in the Northwest Coast ecoregion. The Makah, Quileute, Quinault, Queets, Humptulips, Satsop, Wynoochee, Copalis, Chinook, and Lower Chehalis are among those whose ancestors lived on the rainy coast.

Dwelling in longhouses along the waterways, these peoples thrived on the region’s natural bounty. They ate well: on salmon and shellfish, on game, on whales and seals, and on berries and other plant foods.

Many were exceptionally skilled at making canoes from western red cedar. They traveled in canoes on the rivers, estuaries, and the open ocean. Today, the ecoregion counts half a dozen Indian reservations, the largest being the Quinault and the Makah.

Captain James Cook, exploring the region in 1778, was likely the first European to see the coast. Many other Europeans, primarily British and Spanish, soon followed. The diseases they brought devastated the populations of the indigenous peoples.

The fur-trade period (1790s–1850s) was followed by Euro-American settlers in the mid-nineteenth century. Settlement gained momentum following the treaties of 1854-5.

Photo: Olympic National Park

The rich timber resource of Douglas-fir, western red cedar, western hemlock, and Sitka spruce provided livelihoods for generations of Euro-Americans in the Northwest Coast ecoregion.

While timber remains an economic powerhouse, the harvest of non-timber forest products is increasingly important. Mushrooms, ferns, mosses, and salal all find their way to market.

The marine environment sustains commercial and sport fishing, crabbing, clamming, and oyster growing. On land, agriculture includes cranberry bogs and dairy farms. Tourism and recreation activities increase yearly.

Today the ecoregion is dotted with small communities and one growing metropolitan area, Aberdeen-Hoquiam in Grays Harbor County. Within the ecoregion, more than 50% of the land is privately held—much of it by timber companies. Another 30% is federally owned. The remainder is held by the state, local, and tribal governments.

The U.S. Forest Service, through the Olympic National Forest, controls about 15% of the region. Much of its lands have seen considerable impacts from logging activities.

The ecoregion’s largest wildland area is Olympic National Park. It has been recognized as a World Heritage Site by the United Nations Educational, Scientific and Cultural Organization (UNESCO).

Human Impact

The Northwest Coast’s marine and terrestrial ecosystems face myriad human-caused challenges to biodiversity conservation.

In nearshore and marine habitats these challenges include:

• Shoreline modification. Construction of jetties, bulkheads, and other armoring features has disrupted natural wave functions and led to shoreline erosion. In just one century, the jetty at Grays Harbor has reconfigured the estuary, changing it from a shallow bay with sandy beaches to a steep-faced shoreline with a deeper nearshore.

• Estuary conversion. More than 80% of the state’s estuarine ecosystems have been converted to other uses. Nearly all of what remains has been degraded. Roughly 40% of the Columbia River estuary has been drained to become dry land.

• Marine invasive non-native species. Smooth cordgrass (Spartina) covers nearly a third of Willapa Bay’s mudflats. It alters the funcitoning of the mudflats and challenges oyster culture.

Challenges to the terrestrial environment include:

• Low density sprawl. Beach communities like Westport and Ocean Shores face creeping residential and commercial development. This can disrupt the natural forces at work on beaches and dunes, and in turn disturb or dislocate the natural flora and fauna.

• Past forest management practices. Many of the forests in the Northwest Coast ecoregion have seen several harvest cycles. This legacy of single-aged stands, altered hydrology, and soil erosion creates challenges for biodiversity conservation.

• Invasive plant and animal species. Reed canary grass chokes many wetlands and streams. Himalayan blackberry, gorse, Scot’s broom and many others threaten the habitats of native plants and animals.