Summary: Over the last several decades, tens of thousands of miles of simple dirt and gravel roads have been built across forested public land in the United States. Today, managers from the U.S. Forest Service (and other federal and state agencies) have insufficient funding to maintain these roads and have been directed to begin strategically reducing road densities, despite a lack of public support in many regions. When roads are removed or stored, it is often difficult to show that these restoration treatments are cost effective and/or improve aquatic process and function at either site- or watershed-scales. Resolving these issues has become an increasingly urgent matter for managers across the western United States. Several decades of published research have linked roads to stream habitat degradation. Further, high road densities have been correlated to the decline of sensitive species like bull trout across broad areas like the interior Columbia Basin. Research has shown that all roads do not affect aquatic systems equally, and many roads may have little or no effect on stream function and native trout habitat.
Here, with support from the Forest Service, the GNLCC, the University of Montana, and several local, regional, and national NGOs, the Southwestern Crown of the Continent Collaborative aquatic monitoring group has married two proven monitoring approaches to establish clear road restoration priorities for both managers and the general public, while simultaneously developing new tools to quantify the effectiveness of restoration treatments on aquatic systems. First, we have applied an empirical methodology known as GRAIP (Geomorphic Roads Analysis and Inventory Package) to monitor hillslope road and stream interactions. GRAIP both locates and estimates fine sediment generation produced on road surfaces and delivered to the stream. This tool has been combined with channel monitoring strategy known as PIBO (monitoring for the PacFish InFish Biological Opinion) that was originally developed to monitor sub-watershed changes over time in the Columbia Basin. The use of PIBO data to describe effectiveness based on sampling a single sub-watershed is inappropriate. Therefore, the sampling protocol was modified by simplifying data collection at a single site, while increasing the number of sites sampled within sub-watersheds to achieve an adequate sample size. Modified PIBO results are used to analyze relationships between in-stream channel conditions (including substrate condition) and road sediment delivery from GRAIP.
Our approach has broad application to multiple federal and state agencies across the GNLCC region and in three additional LCC's, and will provide estimates of road effects at the scale of entire watersheds while establishing a foundation for long-term monitoring programs of aquatic ecosystems and native trout habitat as climate change continues to accelerate.
