Historical Habitat Change in the Lower Columbia River, 1870 - 2010

The Historical Habitat Change Analysis is the primary line of evidence in our Restoration Prioritization Strategy. Using funding provided by the EPA, the Estuary Partnership recently completed a habitat change analysis for the lower Columbia floodplain, by comparing our 2010 land cover data set to GIS interpretations of late 1800s survey maps drawn by the Office of Coast Survey and the General Land Office. The GIS interpretations of the historical data maps were created by the University of Washington WET lab, and the Oregon Natural Heritage Information Center, respectively.  Comparison of current data to these historical data provides a detailed perspective of the changes in habitat types which have occurred over approximately the last 120 years, and can help to inform habitat restoration efforts.

It is important to remember that this analysis is based on comparisons of multiple data sources, which have been created based on the interpretations of their respective authors. This is particularly true for the historical data sets.  Authors were reliant on survey notes and maps that were generated more than 100 years ago. We believe that these information sources have been represented faithfully in the data sets, however we can only assume that the source nformation itself is accurate and representative of the actual historical ground conditions.  The quality of the maps, and the availability of metadata describing the maps and the survey processes provides a reasonable level of confidence in this assumption.

The map below illustrates results of the analysis for wetlands habitats.  These habitats are of considerable importance for fish and wildlife species.  Both herbaceous and wooded wetlands, once prevalant throughout the lower Columbia River floodplain, show extensive losses over the last century.  Losses have occurred due to several factors, including conversion of lands for agriculture and development, as well as reduced flows as a result of the hydropower system.  Though smaller in overall area compared to the wetlands losses, other areas have seen increases in wetlands habitats, or have remained wetlands since historical times.  Overall, the map illustrates a dynamic habitat regime with a shifting mosaic of habitat types.
 

View/Download the Historical Habitat Change Analysis Final Report

 

Priority Habitat Recovery

The Estuary Partnership has used the results of this change analysis to prioritize habitat types for recovery and protection throughout the lower Columbia.  We used the Ecosystem Classification System as a basis, prioritizing habitat types for each of the Level 3 Hydrogeomorphic Reaches in the Classification.  These habitat priorities, and their respective targeted acreages, will be available in the Restoration Strategy Document when it is completed.  In addition, we have begun to quantify how much of these priority habitats might potentially be recovered, and are using this information to set target acreages for conservation and recovery.  To view maps illustrating the distribution of existing, recoverable, and non-recoverable priority habitats, click on the following maps generated for each of the 8 Reaches:

Recoverable Priority Habitats:  Reaches A and B   Reach C   Reach D   Reach E   Reach F   Reach G   Reach H

 

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