Citation:

Hohman, S., R. Shatkay, S. Kaushal, AND P. Mayer. Tracking downstream water quality benefits of urban stream restoration. 13th National Monitoring Conference, Virginia Beach, VA, April 24 - 28, 2023.

Impact/Purpose:

Nonpoint source pollution in urban streams is a serious water quality issue that is increasingly addressed with management approaches involving stream channel and floodplain restoration.  Such approaches are expensive, and the efficacy of urban stream restoration is poorly understood despite billions (US$) spent because monitoring of projects often is not done and/or is poorly designed, leaving gaps in our understanding of best management practices, particularly the question of how local restoration efforts affect downstream water quality.  This R2P2 study is designed to improve our understanding of restoration efficacy in the context of nutrient and heavy metal pollution reduction by implementing high resolution monitoring and synoptic sampling of a restored stream in the Chesapeake Bay watershed.  Our results will be used to identify effective stream monitoring strategies as well as quantify the efficacy of channel modification as a restoration approach.  Our results are intended to inform restoration efforts in the Chesapeake Bay to meet TMDL objectives.   

Description:

Nonpoint source pollution is often the most significant source of pollution in streams of concern to resource managers across states, tribes, territories, and federal regulators. Urbanization and impervious surface cover contribute to increased nonpoint sources of nitrogen, phosphorus, sediment, heavy metal, and base cation concentrations in runoff. Additionally, urban streams suffer from streambank erosion and hydrologic disconnection, further contributing to the degradation of water quality and stream health. Stream restoration best management practices (BMPs) are often implemented to mitigate the impacts of urbanization, reduce pollutant concentrations, and improve stream health and water quality. The Clean Water Act Section 319 nonpoint source management program (319 program) provides federal assistance to state and local efforts to combat nonpoint source pollution. In the 319 program, it is presumed that all load reductions and benefits of stream restoration BMPs propagate downstream of BMP implementation, however there is little research to validate this assumption. We sampled Paint Branch Creek, an urban stream in Maryland, USA, every two weeks using high spatial resolution longitudinal monitoring from the headwaters to the mouth to identify how stream water quality (dissolved oxygen, conductivity, total dissolved solids, nitrogen, carbon, base cations, heavy metals) change along an urban stream with different land use features and restoration activities. Additionally, we sampled three restored stream reaches (above the restored reach and 0, 100, and 200 meters below the restored reach) to characterize how far downstream the water quality benefits, or tradeoffs, of various stream restoration activities propagate. Initial results suggest that dissolved oxygen, conductivity, total dissolved solids, pH, and salinity increase while oxidation reduction potential decreases moving downstream. Correlations between stream characteristics suggest that land use influences water quality in these streams. Improving our understanding of the efficacy and downstream benefits of stream restoration activities will allow stream restoration managers and stakeholders to better design, select, and implement restoration activities to maximize pollutant load reductions, stream health, and water quality improvements on broader/larger watershed scales.

Record Details: