Cleaning up a Chesapeake Bay watershed
The Cedar Run watershed, located in Cumberland County in south-central Pennsylvania, has a drainage area of 13.86 sq miles. Cedar Run is a tributary of Yellow Breeches Creek (a 219-sq-mile watershed), which in turn is a tributary to the Susquehanna River (with a 27,510-sq-mile drainage area). The Susquehanna flows into the Chesapeake Bay and accounts for more than 50% of the freshwater flowing into the bay.
From 1978 through 2011, the Susquehanna delivered an average annual load of 71,000 tons of nitrogen, 3,300 tons of phosphorus and 2.5 million tons of sediment to the bay. In 2011, these values increased to 135,000 tons of nitrogen, 17,400 tons of phosphorus and 24.3 million tons of sediment. Two factors contributing to these increases were Tropical Storm Lee and the three large reservoirs on the lower Susquehanna becoming almost completely full of sediment.
Cedar Run consists of a main branch and three sub-branches. The stream is designated as a cold water stream because its sources are primarily springs and the stream supports a wild trout fishery. Unfortunately, Cedar Run also has almost 5 miles designated impaired due to nutrients and siltation from urban runoff and storm sewers. The watershed is in an urban area where more than 50% of the drainage basin is covered with impervious surfaces. Existing open space and agricultural land use (currently about 16% of the drainage basin) is anticipated to disappear by 2020.
Storm water is the most prevalent water quality issue in the watershed. In 2009, Cedar Run was designated as the most degraded tributary in the Yellow Breeches watershed. Nonpoint source pollutants such as nutrients, sediment, various organic chemicals and petroleum products drained from the largely unbuffered land into Cedar Run. Poor agricultural practices, a lack of buffers along the stream and improper use of lawn care products resulted in increased sedimentation and nutrient loads.
To address the impaired condition of Cedar Run, the Alliance for the Chesapeake Bay conducted a watershed assessment, which included a storm water retrofit inventory. The local governmental and non-governmental organizations, individuals and companies provided support for the project. The assessment included three components:
- A stream walk to evaluate physical and floodplain conditions;
- An evaluation of residential, commercial and industrial upland areas; and
- A review of storm water management practices and infrastructure.
The assessment identified specific areas for buffers to be restored, areas where the channel could be stabilized and areas where stream bank erosion could be repaired. Recommendations were made for site-specific storm water management practices such as bioretention, constructed wetlands, sand filters, dry swales and harvesting rainwater from roofs of commercial and industrial buildings. The pollution severity of each site was correlated with restoration potential so that sites could be prioritized. Recommended storm water management practices were made for each site. The completion of a large bioretention basin at an elementary school is an example of implementing one of the recommendations.
The Cedar Run watershed assessment is a step forward in improving water quality in Cedar Run, Yellow Breeches Creek, the Susquehanna River and the Chesapeake Bay.