Alteration to naturally-occurring patterns of streamflow is frequently cited among the most serious threats to ecological sustainability of freshwater ecosystems. Recent floods and droughts have elevated the awareness of the need to protect and restore hydrologic processes that both support ecological integrity and ensure the availability of water for human use. The dynamic nature of rivers poses challenges to water managers.

Fortunately, innovations are emerging as hydrologists, ecologists, water managers, engineers and professionals from related disciplines focus on this challenge. Over the past two years, our project team has been collaborating with natural resource agencies and organizations to evaluate how other states and countries are addressing this challenge, with the goal of recommending the most promising approaches for implementation in Pennsylvania. The ability to characterize baseline (minimally impacted) streamflow conditions, compare them with current and future conditions and assess impacts of human activities on streamflow is fundamental to implementing water management programs that protect and restore environmental flows.

As a foundational step to the ultimate goal of developing environmental flow criteria for water management, The Nature Conservancy, Susquehanna River Basin Commission and the U.S. Geological Survey Pennsylvania Water Science Center propose to develop a tool to simulate baseline streamflow conditions at a daily time scale for streams and rivers in Pennsylvania. The project team will engage the existing Pennsylvania Instream Flow Advisory Committee in all project deliverables. This committee, which is led by the Pennsylvania Department of Environmental Protection, includes state, federal and basin commission resource agency staff with extensive experience on technical and regulatory aspects of water management. Within two years of the project start date, we propose to deliver a tool that can simulate baseline streamflow conditions for any stream or river in Pennsylvania.