Mapping Tributary Habitat Restoration Projects in the Upper Grande Ronde River to Support Landscape Analysis
Abstract
Stream restoration is increasingly being administered in the Pacific Northwest to improve salmon habitat function and fish abundance, among other goals. Although numerous restoration projects have been completed, many consisting of multiple sites and activity types, few projects have been consistently monitored for effectiveness. Furthermore, monitoring is often conducted at the spatial scale of individual sites, which fails to account for larger scale watershed functions. To support the evaluation of potentially far reaching effects of restoration, restoration project information was compiled and mapped and a method for assessing restoration intensity across work sites was developed. This project is the first step in evaluating the cumulative effect of decades of restoration efforts on habitat condition across a large project area. Restoration project information, including restoration type and associated metrics, was collected for the Upper Grande Ronde River watershed. A total of 4,449 work sites were compiled for the study area, coming from 10 different data archives, with a total of 71 unique metrics relevant to stream habitat function. The predominant time period of projects was from 1994-2014, although some projects were completed in 2015. Metrics include measurements and descriptions of restoration work completed. A data table was created to organize separate work sites, with metrics organized by the type of restoration, referred to as the sub-category. Information about spatial location was available for most work sites and was uploaded into a geographic information system (GIS) to generate a shapefile of work site mid-points. The mid-points were subsequently used to analyze the correspondence between mapped restoration efforts and restoration detected during field visits. Habitat monitoring reaches from the Columbia Habitat Monitoring Program (CHaMP) were visually surveyed for the presence of restoration activities expected based on the GIS map. Of projects that were mapped in GIS, there was a wide range of correspondence in detecting those activities in the field, from 100 percent for floodplain reconnection projects, to 33 percent for planting projects. Stream length treated per work site sub-category is proposed as one means of describing restoration intensity across all work sites, based on that being the most commonly reported and therefore consistently available metric. Further investigation into the statistical significance of using the stream length treated per work site sub-category, and the development of ratings or rankings as a means of assessing restoration, is needed to determine the usefulness in predicting habitat improvements achieved through different restoration techniques.
Authors
Citation
Benge, G.N. 2015. Mapping tributary habitat restoration projects in the upper Grande Ronde River to support landscape analysis. Oregon State University Environmental Sciences Graduate Program report in collaboration with Columbia River Inter-Tribal Fish Commission. Portland, OR. 51p.