R/WS-2

Strategic focus area:

Description:

OBJECTIVES: We propose to create a technical brief that can guide decisions regarding stream restoration and that can be used by water quality managers to examine if/when stream restoration may be effective, inform restoration approaches based on site characteristics, and identify factors contributing to variability in outcomes.

METHODOLOGY: The technical brief will contain a: (1) literature synthesis (2) meta-analysis, and (3) decision support tool. The proposed research will investigate stream restoration effectiveness by conducting a literature synthesis profiling projects and successful and unsuccessful outcomes, performing a meta-analysis of existing data on rates of N removal, and develop a decision support tool based on results from the meta-analysis. Generally, engineered approaches to stream restoration have fallen into two broad categories, 1) in-stream manipulation and 2) integrated stream-wetland complexes. The literature synthesis and meta-analysis will involve comprehensively searching the literature for all available published data, as well as grey literature, at global, state, and local levels with an emphasis on Maryland Piedmont streams. We will identify and specify criteria for selection of papers and guidelines for QA/QC of data sets. We will extract information on % N removal from the papers and reports, and develop a standard metric of N removal for study comparison. We will then identify appropriate a priori methods for the analysis of data including curvilinear fits, categorization of data into explanatory variables and controls. This information will be used to construct a decision support tool and conceptual model for guiding stream restoration and informing if/when restoration approaches are likely to be effective within a watershed context. We will submit a draft version of the technical brief for peer review and demonstration at a pilot user workshop. Once we receive feedback, we will revise, prepare the final technical brief, submit for publication as a peer-reviewed EPA Technical Brief, and disseminate to end users via a workshop and websites.

RATIONALE: Water quality managers are faced with increasing regulatory requirements such as Total Maximum Daily Loads and permitting to reduce nitrogen loads in coastal tributaries. Various best management practices including source reduction, land-use management, and riparian buffers are employed to remediate stream impairment from nutrients. A growing body of literature from research conducted in Maryland and elsewhere suggests that stream restoration may have the potential to represent an effective nutrient BMP because denitrification and N removal in streams can increase after restoration under certain conditions. Stream restoration can be performed in areas that were developed in uplands prior to current stormwater regulations and can be coupled with bank stabilization efforts and repair of aging storm water and sanitary infrastructure. However, there may be variability in outcomes and effectiveness of N removal associated with different engineered stream restoration approaches (in-stream manipulation vs. integrated stream-wetland complexes). Although research on stream restoration has been distributed in the peer-reviewed literature, it has not been synthesized and summarized into an easy to use technical brief, particularly suited for water quality managers in the region where measurements were made. We propose to develop a technical brief based on comprehensive analysis of all available empirical data and also within a geographic context of where data were collected, that will aid water quality managers in efforts to effectively employ stream restoration in urbanizing watersheds of the Maryland Piedmont. We will leverage previously funded research from U.S. Environmental Protection Agency (EPA), Maryland Sea Grant, and National Science Foundation that has quantified effects of urban stream and wetland restoration on denitrification and N removal with varying site characteristics and engineered stream restoration approaches.