Implementing Vernal Pools in Mid-Atlantic Stream Restoration Projects
Ethan Daviau
Gannett Fleming
Owings Mills, MD
Authors: Ethan Daviau and Dennis Genito
Vernal pools are seasonal depressional wetlands that are wet for variable periods of time and maybe dry most of the summer and fall. Vernal pools may be accompanied by delicate flora and fauna species that rely on their seasonality and can be critical areas for amphibian reproduction. Habitat diversity is a challenge for stream restoration projects in urbanized watersheds where confined stream valleys are common. Furthermore, habitat loss for both aquatic and terrestrial fauna is being used as an argument against the application of stream restoration projects in urban watersheds. One way to increase habitat diversity on the floodplain and improve biological function in stream restoration projects is vernal pools. In recent years, Gannett Fleming has worked with Baltimore County Department of Environmental Protection and Sustainability (DEPS) to implement and monitor vernal pools on the floodplains of two stream restoration projects, Cooper Branch and Cedar Branch. For these projects, vernal pools were implemented to increase habitat diversity, promote ecological function, and provide flood storage on the floodplain. Although constructed wetlands were not a primary goal of these projects, vernal pools can be an easy way to increase habitat diversity, improve water quality, retain flood flows, and increase ecosystem services in confined valley stream restoration projects.
In total, 10 vernal pools were constructed and monitored across the two Baltimore County stream restoration projects. Post-construction biological monitoring was conducted to evaluate the colonization of vernal pools by benthic macroinvertebrates, amphibians, and other flora and fauna. Public concerns over the potential for increasing numbers of disease-carrying mosquitos, due to standing water in constructed vernal pool depressions, also contributed to the monitoring efforts. Although not all vernal pools functioned as intended, several takeaways exist regarding landscape position, source water, construction, function, and colonization of vernal pools on the floodplain of stream restoration projects in Baltimore County, MD. When these lessons are applied, it is expected that vernal pools can be utilized to provide habitat and floodplain diversity to urban stream restorations in the Mid-Atlantic and beyond.
About Ethan Daviau
Ethan has been an Environmental Scientist for Gannett Fleming in the Owings Mills, Maryland office for the past two years. He has a bachelor’s degree in Environmental Resource Management from Penn State University. Ethan has experience in stream and floodplain restoration design and monitoring, wetland delineation, stormwater facility site selection, BMP maintenance inspection, and construction inspection.
