Surface and Groundwater Modeling of Bog Turtle Habitats

Protecting the natural environment while fostering local development is one of the main challenges that engineers face today. New species are added to the federally threatened and endangered species lists as their habitats are destroyed by residential and commercial development. The bog turtle (clemmys muhlenbergii) is threatened by new development that damages not only its wetland habitat, but the upland areas that drain into the wetlands. The bog turtle was listed as federally threatened in 1997. Protection of bog turtle habitat is a concern to many state and local governments because its habitat is often located near prime land slated for commercial, residential, and transportation related development. Until recently, there was little information available about the water sources that feed these wetland habitats. The Maryland State Highway Administration, in conjunction with other Maryland and federal agencies, has formed a biological assessment team in order to develop a protection plan for one such bog turtle habitat by investigating the hydrology associated with bog turtle habitats. The primary objectives of the hydrologic investigations are to: 1) identify and monitor the major hydrologic inputs/outputs; 2) identify and monitor the major recharge/discharge zones; 3) develop recommendations for future development and stormwater management; and 4) use the results of this analyses as a guideline for developing future protection plans for the bog turtle. Although there has been much recent research on the habitat, genetics, and movements of bog turtles, this is the first large scale study of the hydrology of the bog turtle habitat. An extensive field monitoring network was installed throughout the 8.8 km² watershed. The field data was used to set up and calibrate groundwater and surface water flow models. Surface and groundwater models were developed for the watershed and the results were used to develop a water budget for the bog turtle habitats. The model results provided state and local planners with estimates of seasonal average groundwater table elevations and streamflows. A series of proposed condition models were developed to predict changes in seasonal average levels in order to assess the impacts of the development on the local groundwater table and the wetlands water supply. This information will be used to develop the first major bog turtle preserve in the state of Maryland. The information should be valuable to other Mid-Atlantic states who are facing similar declines in their bog turtle habitats and populations.