Effects of Stream Restoration

Statement of Problem:

Nitrate (NO3) is a common pollutant in watersheds throughout the world. Riparian zones of streams, the vegetated region parallel to stream ecosystems, attenuate anthropogenic nitrate through microbial denitrification, a process that occurs only under anaerobic conditions (e.g. saturated soils) and is limited by supply of dissolved organic carbon (DOC) to microbes. The hyporheic zone of streams, the region in which stream and ground waters mix, also is thought to be a zone of high denitrification activity. Restoring and manipulating these zones to enhance denitrification processes may provide important tools for reducing nitrate pollution in watersheds.

Stream reaches in several locations in Baltimore County, Maryland, have been restored using Rosgen approaches, to reconstruct highly incised streambeds. Restoration has involved replacing lost sediments to elevate streambeds, planting vegetation in riparian zones, and reconstructing point bars and stream meander features. Although these efforts aim to restore stream geomorphic stability, the benefits for improving stream water quality have not been quantified. This research will investigate the effects of restoration on stream hydrology, denitrification, and overall water quality.

Strategy and Approach:

1. Watershed Reconnaissance
2. Sediment and Stream Geometry Monitoring
3. Surface/Subsurface Water Interaction Characterization
4. Surface Water Evaluation/Monitoring
5. Water Quality Sampling--Pre and Post Restoration
6. Bromide Stream Tracer Test