A top priority identified by the group was to address coastal erosion impacts adjacent to the inlet. For years, the Lower Columbia Solutions Group and other State, federal, and community constituents met regularly to address sediment management at the MCR. Studying the complex interactions of dredging, sediment supply, and coastal processes at the MCR to inform sediment management required understanding the concerns of a diverse set of stakeholders. Geological Survey (USGS), Washington State Department of Ecology, and Oregon State university revealed that over 2 million cubic meters of sediment eroded from Benson Beach between 20.ĭredging, Nearshore Habitats, and Erosion at the River Mouth Bathymetric and topographic surveys performed annually by the U.S.

And as rising sea levels accelerate coastal erosion, a steady supply of quality beach sand is critical to keeping coastal areas above water.ĭirectly north of the MCR, for example, at Benson Beach, erosion has been problematic for decades. This process can have significant impacts on adjacent beaches over time by depriving them of sand. Historically, some dredged sediment was disposed of offshore in deep water.

Today, the U.S Army Corps of Engineers (USACE) dredges between 1.7 and 3.5 million tons (between 2 and 4 million cubic meters) of sediment from the six-mile-long entrance channel at the river mouth each year. Since 1891, the MCR has been dredged to facilitate safe passage of large commercial vessels.

Before the inlet was improved for navigation in the early 20th century, passage from the river mouth to the ocean was so treacherous that the area was known to mariners as the “Graveyard of the Pacific”. Visit Media to see details.Ĭolumbia River mouth bathymetry from USGS data releaseĪt unaltered river deltas, processes such as wind, waves, and currents distribute this sediment across adjacent coastal areas-some will be deposited onshore and in nearshore environments, while some is transported further offshore.īut the Mouth of the Columbia River (MCR), like most major inlets around the world, is engineered for shipping traffic, with rock jetties that concentrate its flow into navigable channels.

How does river dredging work