The Willamette Floodplain consists of 713 acres (288.5 ha) of natural grassland that was made a National Natural Landmark

National Natural Landmark

The National Natural Landmark program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only natural areas program of national scope that identifies and recognizes the best examples of biological and geological features in...

 near the Willamette River

Willamette River

The Willamette River is a major tributary of the Columbia River, accounting for 12 to 15 percent of the Columbia's flow. The Willamette's main stem is long, lying entirely in northwestern Oregon in the United States...

 in May 1987. The floodplain

Floodplain

A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...

 is within the William L. Finley National Wildlife Refuge

William L. Finley National Wildlife Refuge

William L. Finley National Wildlife Refuge is a natural area in the Willamette Valley in Oregon, United States. It was created to provide wintering habitat for Dusky Canada Geese. Unlike other Canada Geese, Dusky Canada Geese have limited summer and winter ranges. They nest on Alaska's Copper River...

 and located about 15 miles (24 km) south of Corvallis

Corvallis, Oregon

Corvallis is a city located in central western Oregon, United States. It is the county seat of Benton County and the principal city of the Corvallis, Oregon Metropolitan Statistical Area, which encompasses all of Benton County. As of the 2010 United States Census, the population was 54,462....

 in Benton County, Oregon

Benton County, Oregon

-National protected areas:*Siuslaw National Forest *William L. Finley National Wildlife Refuge-Demographics:As of the census of 2000, there were 78,153 people, 30,145 households, and 18,237 families residing in the county. The population density was 116 people per square mile . There were 31,980...

, near Willamette RM

River mile

In the United States, a River mile is a measure of distance in miles along a river from its mouth. River mile numbers begin at zero and increase further upstream. The corresponding metric unit using kilometers is the River kilometer...

 150.

It is the largest remaining native unplowed example of bottomland interior valley grassland

Grassland

Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...

 in the North Pacific Border natural region. It was classified as a natural landmark because such grassland

Grassland

Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...

 and shrubland

Shrubland

Shrubland, scrubland, scrub or brush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity...

 areas are exceedingly rare, with most having been cultivated or turned into pastureland.

The Long Tom River

Long Tom River

The Long Tom River is a tributary of the Willamette River in western Oregon in the United States. It drains an area at the south end of the Willamette Valley between Eugene and Corvallis....

 joins the Willamette in the area. There are numerous meanders, many disconnected from the Willamette. The Irish Bend Covered Bridge

Irish Bend Covered Bridge

Irish Bend Covered Bridge is a wooden covered bridge near Corvallis, Oregon, United States. It was constructed in 1954 and originally spanned the Willamette Slough on Irish Bend Road near Monroe. However, in 1975 Irish Bend Road was realigned and the bridge fell into a state of disrepair. The...

crosses one of them.