The Columbia River Estuary
The word estuary comes from the Latin aestus meaning a heaving or surging motion. An estuary represents that portion of the conclusion of a river where the current flow is affected by the tides of the ocean. Here on the Great River of the West the estuary is an area of mudflats, sand bars, islands, and tidal marshes. The land area alone is nearly 10,000 acres. The Lewis and Clark National Wildlife Refuge is within the estuary and includes some thirty-five thousand acres. With the exception of a few house boats the area is uninhabited by humans.
As the river flow reaches the resistance of the ocean tides the water drops some of their millions of tons of sand and silt. A sand bar forms, grows and soon stands above the tide. Seeds are deposited and germinate. The growth catches wind born sand and the landform grows still more. Plants decay and become food for small organisms which in turn provide a food source for more animal life like fish and clams. Birds feed on these and their droppings renew the cycle by enriching the soil for more plant growth.
This morning we decided to explore some of its treasures by Zodiac. The exposed banks erode with the full moon extremes and clumps of soil and grass drop with the falling tide. At the islands' edge are the marsh grasses. Behind the grasses stand the willows, cottonwood trees and spruce. Bird counts record 175 different species in the marshes. The isolation of the islands and absence of humans is one reason for the great numbers of birds. During the fall and winter months great masses of waterfowl use the tidal marshes to feed in before migrating south. The list of land mammals to be found here is equally impressive. Mice, vole, shrew, coyote, fox, rabbit, raccoon, skunk and more call the refuge home. A few, rare Columbia White-tailed Deer inhabit one of the islands.
In 1977 an inventory of the estuary and its resources was taken to help develop a land use and preservation plan for the lower Columbia. The inventory of these islands helped in reaching the conclusion that the estuary stood as an important part of the river and it could be best served by leaving it untouched. And so it is today; a place to be visited and left undisturbed.
The word estuary comes from the Latin aestus meaning a heaving or surging motion. An estuary represents that portion of the conclusion of a river where the current flow is affected by the tides of the ocean. Here on the Great River of the West the estuary is an area of mudflats, sand bars, islands, and tidal marshes. The land area alone is nearly 10,000 acres. The Lewis and Clark National Wildlife Refuge is within the estuary and includes some thirty-five thousand acres. With the exception of a few house boats the area is uninhabited by humans.
As the river flow reaches the resistance of the ocean tides the water drops some of their millions of tons of sand and silt. A sand bar forms, grows and soon stands above the tide. Seeds are deposited and germinate. The growth catches wind born sand and the landform grows still more. Plants decay and become food for small organisms which in turn provide a food source for more animal life like fish and clams. Birds feed on these and their droppings renew the cycle by enriching the soil for more plant growth.
This morning we decided to explore some of its treasures by Zodiac. The exposed banks erode with the full moon extremes and clumps of soil and grass drop with the falling tide. At the islands' edge are the marsh grasses. Behind the grasses stand the willows, cottonwood trees and spruce. Bird counts record 175 different species in the marshes. The isolation of the islands and absence of humans is one reason for the great numbers of birds. During the fall and winter months great masses of waterfowl use the tidal marshes to feed in before migrating south. The list of land mammals to be found here is equally impressive. Mice, vole, shrew, coyote, fox, rabbit, raccoon, skunk and more call the refuge home. A few, rare Columbia White-tailed Deer inhabit one of the islands.
In 1977 an inventory of the estuary and its resources was taken to help develop a land use and preservation plan for the lower Columbia. The inventory of these islands helped in reaching the conclusion that the estuary stood as an important part of the river and it could be best served by leaving it untouched. And so it is today; a place to be visited and left undisturbed.
