Assessing Dungeness River Functionality and Effectiveness of Best Management Practices (BMPs) Using an Ecological Functional Approach.

ABSTRACT

Effective stream and wetland Best Management Practices (BMPs) restore the physical processes associated with ecological functions to their Proper Functioning Condition (PFC, i.e., the highest attainable ecological status of a riparian area without consideration of economic, administrative, or social constraints). Ecological functions connect stream monitoring and management to mitigate the causes of ecosystem degradation and enhance restoration. The ecological function approach supports sustainable management of many ecosystem services including water quality, water stability (aquifer recharge), and fish and wildlife habitats. The 1993 Forest Ecosystem Management Assessment Team (FEMAT) report listed the Dungeness River as a Tier 1 key watershed, noted that watersheds are the logical spatial unit for ecosystem management, and that watersheds are important in species management, and understanding the interdependence of physical processes. Watersheds are at the spatial scale where physical and biological disturbances can be observed, and where management constraints and planning options for restoration objectives and strategies can be readily assessed. The US Forest Service (USFS) developed a management strategy for the Middle Dungeness River, and in the 1990s, the Upper Dungeness River was listed as impaired due to sediment, which initiated a US Forest Service change to land management practices. The Lower Dungeness River and bay are listed as impaired due to fecal coliform contamination. Assessing and monitoring the drivers of ecosystem function (vegetation, hydrology, soil, and landform) as part of a watershed adaptive management plan, and implementing BMPs to increase ecological functions, will improve aquatic habitat and water quality. Most BMPs, such as Total Maximum Daily Loads (TMDLs), attempt to improve water quality by reducing the amount of external pollutants reaching the impacted waterbodies, but do not focus on improving the watershed functions. The Proper Functioning Condition (PFC) approach is used to examine the condition of wetlands and streams and provide guidance for quantitative approaches (e.g., TMDL, remote sensing) used in watershed restoration. Improving watershed functions is a BMP that facilitates increased flows of water, nutrients, sediment, and other materials, and improves habitat quality. Using improved watershed functions as a BMP, facilitated by the use of remote sensing, TMDLs, and the PFC methodology is a more effective means of reducing risks across a watershed than by using TMDLs alone.