Post Restoration Conditions in Cowhide Branch
Characterization of Post Restoration Conditions in Cowhide Branch
Bureau of Watershed Protection and Restoration Contact: Rachel Denby
|Pre-restoration, upstream view of Cowhide Branch and Admiral Drive (2012). The fish blockage can be seen through the culvert.|
Cowhide Branch is a non-tidal stream that flows from the Annapolis Mall to the headwaters of Weems Creek, a tributary of the Severn River. An intense storm event occurring in the 1990’s resulted in the failure of the stormwater management pond embankment in the upper reach of Cowhide Branch. To prevent continued sediment transport from the failed pond to tidal Weems Creek, an emergency weir (dam) was constructed across Cowhide Branch upstream of the Admiral Drive crossing. The dam also prohibited migratory and local fish passage. In 2018, the County completed the Cowhide Branch restoration project to restore fish passage. During the restoration, the dam was removed and the system was converted into a wetland seepage system to open the stream to fish passage. The permit conditions associated with this restoration project require the County to monitor baseline and storm water quality, geomorphology, and biological conditions within and near the project area for five years following restoration completion. Vegetation monitoring, a fundamental component of healthy and functional stream corridors, is also required. Post-construction monitoring was initiated in fall 2018.
- The data collected in this project— water chemistry, biological community health, geomorphological condition, habitat, and vegetation survival—will allow County staff to document ecological conditions and trajectory in Cowhide Branch and assess the effectiveness of the restoration project in providing fish passage.
- Vegetation community surveying will allow staff to assess the rate and trajectory of community succession over time, as well as the presence and abundance of non-native or invasive species.
- This project advances the Bureau of Watershed Protection and Restoration’s mission to use high-quality science to assess and inform our restoration programs.
The following post-restoration activities have occurred since fall of 2018:
|A stilling well containing a YSI water sampler and water level plate installed near the culverts.|
- Water Quality Monitoring: Monthly baseflow samples are collected manually (grab samples) and monthly storm water composite samples are collected via automated monitoring equipment; in-situ phys/chem water quality data and precipitation data are recorded continuously at the monitoring station. All water quality samples are analyzed for metals, E. coli, oil and grease, nutrients, and other parameters.
- Biology: Biological surveys of benthic macroinvertebrates, fish, and in-stream habitat are conducted annually within the project area, using methods set forth by the Maryland Biological Stream Survey and the County’s Biological Monitoring Program.
- Geomorphology: Cross-section and longitudinal profile measurements are performed annually within the restored reach and in the upstream/unrestored reaches.
- Flow: Storm flow and baseflow measurements are routinely collected to establish a stage to discharge relationship. Discharge measurements are used with the water chemistry results to determine loading rates from the restored reach.
- Tidal Influence: The Weems Creek mainstem is tidally influenced. Data loggers in stilling wells were installed at the downstream end of the restored reach to determine the post-restoration extent of tidal influence on this project.
- A baseline vegetation survey was completed in July to determine survival rates of planted and native volunteer woody vegetation (trees and shrubs) and re-growth of invasives.
- Initial post-restoration fish surveys were conducted in the summer of 2018. Four sites in the non-restored areas received Poor or Very Poor scores. One site in the restoration area received a Good score. All sites had a range of zero to thirteen different species.
|Staff members conducting geomorphology surveys in a nearby tributary to Cowhide Branch.|
- Baseflow and storm flow water quality will be monitored monthly and flow measurements collected routinely to further develop the stage-discharge relationship.
- Biological monitoring (benthic macroinvertebrate and fish surveys) and geomorphology surveys will continue annually. Of note, the fish survey data will document evidence of fish passage, a priority of this restoration project.
- Vegetation surveys will be conducted annually.
- Data analyses and reporting will be undertaken annually.
|A Bureau of Watershed Protection and Restoration staff member taking discharge measurements downstream of Admiral Drive.|