Stories From The Field

Identifying Historical Wetland Habitat Changes in Oregon

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Issue

A nonprofit partnership is working to preserve and restore the natural ecological habitats of the Lower Columbia River and protect the diverse array of fish and wildlife that these habitats support. The Lower Columbia Estuary Partnership—supported by the U.S. Environmental Protection Agency’s National Estuary Program, the states of Oregon and Washington, and other entities—needed to create and implement a comprehensive conservation and management plan. An important initial step was to inventory the current quality and distribution of these habitats and compare this information against historical conditions.

Process

To help implement its habitat restoration and protection actions, the partnership developed a comprehensive GIS-based Habitat Restoration Prioritization Strategy. To measure how wetland habitats have changed from the time before modern human impacts to the present day, the partnership worked with NOAA’s Coastal Change Analysis Program (C-CAP) to develop an up-to-date land cover map. Land cover was derived by means of NOAA’s national framework method using National Agriculture Imagery Program and available lidar elevation data. The map was then compared to historical baseline data, which were developed using past coastal survey maps and General Land Office land survey data. These historical data sets covered the period from approximately 1870 to 1890, providing a substantial baseline for comparison with current conditions.

Impact

The results provided useful insight into the extent of change and significant declines in vegetated tidal wetlands that occurred in the Lower Columbia River Estuary. Mapping helped the Lower Columbia Estuary Partnership determine that conversion of land for agriculture and urban development was the cause for most habitat loss. The partnership was able to identify various habitat types for recovery and protection for each portion of the river according to their relative extents of loss, as well as their value in supporting various species.

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Comparison of 2010 and historical (late 1800s) wetlands for the lower Columbia

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