Reservoir Management Optimization for Basin-Wide Ecological Restoration in the Connecticut River

Abstract

Evidence from ecological studies suggests that the alteration of river flows downstream of reservoirs can threaten native aquatic ecosystems and the services they offer. Innovative revisions to water management practices are required to improve the health of aquatic species while maintaining the benefits from current infrastructure projects. The impacts of individual reservoir operations on ecosystem vitality are often masked by the uncoordinated and compounding influences of several impoundments upstream, undermining the examination of environmental impacts from particular reservoirs in a large watershed system. This paper presents a large-scale optimization model that investigates the value of coordinated reservoir management practices for ecological benefits in a large watershed with several major reservoir systems operating for a range of management objectives. An application of the model is presented for the Connecticut River watershed, the largest river basin in New England and one of the most impounded rivers in the United States. The model can examine trade-offs between the maintenance of ecologically acceptable, daily streamflows at key locations throughout the watershed and traditional reservoir objectives, including flood risk reduction, municipal and riparian water supply, hydropower production, and recreation. The ecological streamflow targets are designed specifically for the basin’s ecology in a collaborative process engaging regional experts and constitute a unique and innovative component of the modeling approach. This study focuses on the re-operation of a network of federal flood control dams for the restoration of environmental flows. Results suggest that coordinated changes to current flood control reservoir operations can restore aspects of the natural hydrologic flow regime necessary for ecosystem persistence without significantly reducing current flood risk reduction capabilities.