Changing precipitation patterns and an increase in heavy rain and snow events are causing more frequent flooding in certain regions across the globe. The 2014 National Climate Assessment indicated that the Northeastern United States (US) is already experiencing a 70% increase in high intensity rain events. Emerging studies indicate that roadside ditch networks have significantly altered natural hydrologic flows, capturing and shunting the stormwater to streams where it contributes to flooding, pollution and degraded stream ecosystem health.
To date, no comprehensive study of ditch management policy has been conducted in the US. Regional coordination of water management efforts first requires a fact-finding mission to understand existing ditch policies and practices. This research evaluated the existing roadside ditch management system within the six states comprising the Chesapeake Bay Watershed in the eastern US. A survey was conducted of 36 highway professionals acting at state and county levels in 2016 to document the ditch management regulations and actual practices by highway departments working at the county and regional landscape scales. This work builds on a 2014 study which evaluated ditch practices across 999 towns in New York State.
Results indicate there are considerable differences in policies and practices across the Bay states. Each state distributes road ownership differently. New York and Pennsylvania allocate most maintenance responsibilities for roads and ditches to municipal (town and city) governments, whereas Maryland assigns most responsibilities to county departments. Roads and highways in Delaware, Virginia, and West Virginia are predominantly managed by state-level highway departments.
Most highway managers are aware of downstream threats of flooding, pollution, and erosion posed by ditch runoff. However, management practices that exacerbate downstream risks remain common. The 2014 NYS study indicated that about half of the highway managers were aware of best management practices but did not generally implement them due to lack of financial resources, inappropriate equipment, and lack of support from municipal policy makers. We found that similar challenges, along with poor road and culvert design, were driving inadequate management across the Chesapeake watershed.
Recent studies suggest that well-designed and well-maintained ditches can buffer impacts of climate change. Water management strategies that slow down flows, promote ground infiltration, and divert runoff to ponded areas that do not artificially feed into local waterways can significantly decrease harmful ditch impacts. Because water flows across landscapes, reduction of flooding and pollution will not be possible without coordination across boundaries. Results of this study indicate that there is currently no coordinated management of roadside ditch networks across political jurisdictions, but opportunities exist for training and collaboration.