An Interdisciplinary Study of the Effects of Groundwater Extraction on Freshwater Fishes

Abstract

The aquatic communities in fluvial systems are to a large extent an expression of the dynamic inter- and intra-annual variability in the hydrologic regime of that system and region. To assess the degree to which alteration of the hydrologic regime has affected expressions of ecological integrity, it is necessary to construct reference hydrologic conditions, altered flow regimes, and metrics of change from the reference condition. In this work, an interdisciplinary approach is applied to assess the effects of groundwater extraction on aquatic fauna (brown trout, tessellated darter, and fallfish) in a case study involving the University of Connecticut Fenton River Well Field, Storrs, Connecticut. The study design addressed the interactive components of longitudinal, vertical and temporal connectivity, emphasizing the interaction of biology and, groundwater and surface water hydrology. The development of a simulated discharge time-series and quantification of the degree of effect of groundwater extraction on discharge were central to defining a water management strategy to minimize deviations in intra- and inter-annual habitat availability. Implementation of this strategy involves adjusting groundwater extraction rates based on the magnitude and duration of daily stream discharge. Applying species specific and community habitat thresholds (common, critical and rare) and corresponding maximum durations as fixed flow rules would have avoided the habitat depletion events observed in the summer of 2005.