In 2011, The Wetlands Conservancy (TWC) developed a conservation plan for the Yaquina Estuary in Lincoln County, Oregon. Part of the analysis required an understanding of sedimentation processes and threats throughout the watershed. Clear-cut timber harvests have long been identified as a potentially significant contributor to excess sediment loads in streams, and eventually to estuaries. However, timber harvest records on private lands are not centralized or available in GIS format, making it difficult to quantify sedimentation processes and threats throughout the watershed.
TWC used NOAA’s Coastal Change Analyses Program (C-CAP), a nationally standardized database of land cover and land change information for the coastal regions of the U.S., to detect timber harvest activities over five-year intervals (1996-2001 and 2001-2006) in the Yaquina watershed. This selection of C-CAP change data, which was combined into a single coverage, gave an approximation of clear-cut timber harvest areas. A comparison with pre- and post-dated aerial imagery confirmed the utility of the approach.
The C-CAP data provided a quick and reasonably accurate representation of clear-cuts. This information was analyzed along with impervious surface data (from the U.S. Geological Survey’s National Land Cover Database), allowing TWC to better understand freshwater inputs from these features and their effects on the sedimentation processes in the watershed. This information, included in the Yaquina Estuary Conservation Plan, is now guiding TWC’s conservation efforts, promoting the selection of acquisition and restoration projects that address critical watershed and estuary processes, functions, and restoration opportunities.