Managing dams for energy and fish tradeoffs: What does a win-win solution take?

Area of Science:

• Environmental Science
• Hydropower Engineering
• Fisheries Management

Background:

• Dam operations for endangered species restoration often reduce hydropower output.
• Quantitative analysis of energy-fish tradeoffs in dam management is limited.

Purpose of the Study:

• To develop an integrated model assessing basin-scale energy-fish tradeoffs under various dam management scenarios.
• To quantify the balance between hydropower generation and migratory fish population recovery.

Main Methods:

• Developed an integrated system dynamics model for hydropower generation and age-structured fish populations.
• Simulated 150 years of daily operations across five dams on the Penobscot River, Maine.
• Used alewife (Alosa pseudoharengus) as a representative diadromous species.

Main Results:

• Without fishways, dams reduce alewife spawner abundance by 90% despite producing 427 GWh/year.
• Fishway effectiveness depends on habitat size and passage rates; natal homing has minimal impact.
• Turbine shutdowns during peak migration increased spawner abundance by 480-550% while preserving 65% of hydropower capacity.

Conclusions:

• A combination of dam management strategies at the basin scale can effectively balance energy production and fish population recovery.
• Integrated management is crucial for sustainable hydropower and migratory fish restoration in river systems with active dams.