You are here

Coast Range

 

Marine & Estuarine Habitats

An estuary is a body of water formed where freshwater from rivers and streams flows into the ocean, mixing with the seawater. Estuaries and the lands surrounding them are places of transition from land to sea, and from freshwater to saltwater. Although influenced by the tides, estuaries are protected from the full force of ocean waves, winds, and storms by the reefs, barrier islands, or fingers of land, mud, or sand that surround them.

Estuary Leeds Island

Oregon Habitat Joint Venture

With an area of nearly three million acres, the Umpqua watershed is the largest watershed south of the Columbia River that drains directly to the Oregon coast. Like many of Oregon's estuaries, the Umpqua is a "drowned river mouth" system, with broad tide flats located low in the system. The Umpqua estuary is strongly influenced by the large volume of fresh water carried by the Umpqua River.

The sheltered waters of the Umpqua River estuary are home to countless plants and animals that like to live in water that is part fresh and part salty. The Umpqua is one of Oregon's most important producers of salmon and steelhead, supporting spawning runs of coho, fall chinook, spring chinook, winter steelhead, and summer steelhead. All these salmonids use the tidal wetlands of the Umpqua estuary to forage and to acclimate to ocean salinities before ocean entry. The estuary is important for waterfowl and many other wetland-dependent species, including several breeding pairs of bald eagles. The estuary also provides critical rearing and feeding habitat for crabs, shellfish such as mussels and oysters (including commercial oyster facilities), and many marine fishes such as lingcod, flounder, and sole.

Estuaries protect water quality by filtering out dirt and pollution. In addition, estuaries and the land surrounding them are places where people live, sail, fish, swim, and bird watch. As a result, estuaries are often the centers of our coastal communities.

Estuaries face a host of common challenges. Because we love and depend on the water, more than half of the people in the United States live within 100 miles of the coast, including on the shores of estuaries. And more and more people are moving to these areas. Coastal communities are growing three times faster than counties elsewhere in the country. In Oregon, overall losses of tidal wetlands since the 1850s are estimated at 70%.

Unfortunately, as more people flock to the shore, we are upsetting the natural balance of estuaries and threatening their health. We endanger our estuaries by polluting the water and building on the lands surrounding them. These activities can contribute to unsafe drinking water, beach and shellfish bed closings, harmful algae blooms, declines in fisheries, loss of habitat, fish kills, and a host of other human health and natural resource problems.

Sources

U.S. Environmental Protection Agency, https://www.epa.gov/environmental-topics/water-topics

Oregon Coastal Atlas, https://www.coastalatlas.net/learn/settings/estuary/index.asp

Brophy, L.S. (Green Point Consulting), and K. So. 2005. Tidal Wetland Prioritization for the Umpqua River Estuary. Prepared for U.S. Fish and Wildlife Service, Oregon Coastal Program, Newport Field Office.