Researchers: Building better dams starts with ecological insights

Water is a valuable commodity in Colorado, and dam-building is almost always a controversial topic due to conflicting needs for water by humans and by the natural environment. A Colorado State University researcher has helped develop a new approach to guiding the development of water projects so that human needs and ecological needs are equally considered when making choices about project design and operation.

Elwha Dam in Washington’s Olympic National Park, prior to its removal. Photo courtesy brewbrooks via Flickr/Creative Commons.

Designing for the ecosystem that we want while meeting societal needs is a key element of the approach.

LeRoy Poff, an ecologist and professor of biology at Colorado State University, says the increasing unpredictability of our climate and uncertainty about future river flows and ecological responses highlight the need for smarter water management systems that engineers, economists and even ecologists can all get behind.

A new paper published Sept. 14 in the peer-reviewed journal Nature Climate Change — led by Poff and 10 co-authors — describes the innovative new methodology for climate adaptation planning, called eco-engineering decision scaling (EEDS), that turns the narrative of “build first, ask questions later” on its head.

A roadmap

EEDS provides a roadmap for integrating ecological principles into the early stages of infrastructure planning and design in a transparent, explicit fashion. The authors of the paper, “Sustainable water management under future uncertainty with eco-engineering decision scaling,” say the method can help planners and decision-makers design dams and other water infrastructure that meet the needs of people and better sustain natural ecosystems, as well as protect costly investments. They developed EEDS as part of an interdisciplinary synthesis research team funded by the National Socio-Environmental Synthesis Center (SESYNC).

“It’s time that decision-makers and engineers try something different and invite ecologists to the table,” Poff said. “Traditionally, ecologists have had the role of ‘fixing’ a degraded ecosystem after a project has already been built. But eco-engineering decision scaling represents a better, more sustainable way of meeting society’s water needs.”

Water infrastructure including dams and levees can be a reliable source of hydropower, flood protection and short-term water supply. It also can accelerate economic development. At the same time, these projects dramatically alter the natural flow regimes of rivers and, consequently, can cause severe disruptions to river ecosystems and the organisms that live within them. For example, dams can block fish migrations, change the quantity and timing of water flow, and transform upstream landscapes by flooding them with reservoirs.

When these projects lead to ecological degradation, it often also comes with economic losses. Glines Canyon and Elwha dams in Washington’s Olympic National Park are a cautionary tale about the social cost associated with ecological degradation: neither dam was built to include any method of fish passage, resulting in the loss of more than 70 miles of salmon spawning and rearing habitat. After a century of electric production, the dams were recently decommissioned and removed in an effort to restore native fish populations. Restoration to repair damaged ecosystems is typically more expensive than designing the dam with socially desired ecological outcomes in the first place.

New approach needed

“When water infrastructure is built, the environment almost invariably loses out,” said John Matthews, secretariat coordinator for the Alliance for Global Water Adaptation (AGWA) and co-author of the paper. “Engineers and economists don’t have the explicit goal of destroying ecosystems, but the environment simply doesn’t fit into the cost–benefit models they use. Decision-makers need a new way of thinking about the ecological impacts of these large water infrastructure projects.”

That’s where EEDS comes in. The method helps planners and decision-makers quantify and compare the engineering, economic and ecological risks of a water infrastructure project from the very beginning. What sets EEDS apart from other decision-making tools is how it integrates future shifts in climate and other factors that cause great uncertainty in designing and operating water infrastructure. The authors say the method can help decision-makers develop water infrastructure plans that are economically and ecologically resilient for years to come, under multiple future climate scenarios.

“Currently in California, there’s a lot of discussion about how to increase social and ecological resilience to drought,” said Ted Grantham, a research biologist at the U.S. Geological Survey and co-author of the paper. “But we don’t actually know the direction and degree of future climate change with much accuracy, which forces us to rethink traditional approaches to both water infrastructure planning and conservation ecology.”

To connect managers and decision-makers with EEDS, a website was developed by AGWA and SESYNC to explain the complexities and capabilities of the methodology. The researchers say they hope it assists with implementing EEDS to design water infrastructure that yields coupled engineering, economic and ecological co-benefits.

The work was supported by the National Socio-Environmental Synthesis Center (SESYNC) with funding received from the National Science Foundation.

More information is available at