ECOHYDROLOGY - EVALUATING SURFACE WATER AND GROUND WATER PATHWAYS IN A STRESSED AQUIFER SYSTEM

Ecohydrology involves an integrated approach to determine the interactions of the ground water system and the surface water system, including wetlands. This approach has not rigorously been followed in many locations. However, with greater concern for stream flow as well as the transport of contaminants between these two interconnected systems a heightened awareness has developed to monitor how these system interact under non-stressed and stressed conditions.

An example of the application of an ecohydrology approach is presented for the development of a new ground water source in a sand and gravel aquifer. For this example, a suitable location was identified adjacent to the Concord River, Concord, Massachusetts. Preliminary ground water exploration indicated that the proposed site could yield 1 million gallons per day. The site contains ponds, the Concord River, potential vernal pools, and rare and endangered species (flora and fauna). An aquifer pumping test plan (i.e. stressed condition) based upon a three well withdrawal configuration, was developed and included 33 monitoring wells, 7 piezometers, and 8 staff gauges. In addition, the thickness of the organic layer was measured in several suspected vernal pools and two of the ponds.

The results of the pre-aquifer pumping test (i.e. non-stressed condition), aquifer pumping test and resource monitoring indicate minimal impacts to the Concord River, ponds, and suspected vernal pools. Two of the three rare and endangered species were identified at the site. The ecohydrology approach to develop a new ground water source or to understand basic ground water - surface water interaction provides information to optimize a ground water withdrawal while minimizing adverse impacts to rare and endangered species, wetlands, and surface water resources. Short and long-term monitoring of the aquifer and overlying water resources is recommended to validate the ecohydrology approach.