Organic Matter Dynamics as Functional Indicators of Stream Condition in Constructed Streams on Virginia Coal Mine Sites

The Clean Water Act [section 404; stream mitigation rule] mandates that operations permitted by the U.S. Army Corps of Engineers (COE) must mitigate streams impacted by valley fill and other mining activities (Register April 10, 2008). Agencies regulating coal mining operations are placing increased emphasis on functional measures for stream assessment. Guidance memoranda issued by the U.S. Environmental Protection Agency (EPA) and COE concerning mining permits state that the regulatory process should “ensure that compensatory mitigation adequately replaces lost stream functions” (2011) and that “permitting will not rely exclusively on an evaluation of structure in place of function” (2010). In this context, successful restoration of stream functions is of concern to industry, regulators, and restoration professionals. Additionally, in 2012 EPA released A Function‐Based Framework for Stream Assessments and Restoration Projects, a document aimed at those implementing stream restorations and assessments, and clearly states that it would benefit “from review, comments, and example experiences and applications” (Harman et al. 2012). The research presented in this report is addressing needs of industry and regulators by directly measuring specific ecosystem functions in stream mitigation efforts on coal mine sites in southwestern Virginia, and can contribute as an example experience and application. Organic matter (OM), primarily as leaf litter and detritus input, serves as habitat and an essential energy source for benthic macroinvertebrates within headwater and downstream ecosystems. Alteration of the sources, production rates, or processing rates of OM due to disturbance could have cascading effects throughout these ecosystems. As a result, we see the assessment of OM dynamics as a crucial component to determine the overall functional condition of streams, and as an integral tool to meet the needs of industry and regulators to evaluate mitigation efforts through direct measurement of a crucial stream functions. To address these needs we are measuring litterfall input, leaf litter decomposition, and periphyton biomass accrual for reconstructions of eight low‐order mining‐impacted streams, and evaluating them via comparison to four minimally impacted reference streams. Relationships of these functional measures with physical, chemical, and biological structural measures are also being investigated.