In the Pacific Northwest, the conversation about hydroelectric dams is complicated: Dams hamper the natural migration of salmon, yet they are an important source of cheap, renewable energy for the region.

In other parts of the world, gray areas still exist, but the conversation about dams is very different, brought on by a critical need for reliable food and energy sources. In tropical river systems such as the Amazon, Congo and the Mekong, river and lake fishing provide food security in some of the world’s poorest regions and would be negatively impacted by an onslaught of new dams. At the same time, existing and future dams planned on these rivers hold the promise of renewable energy in places that arguably need it the most.

There, the debate is over when and how — not whether — dams will be built and operated.

In Southeast Asia, the Mekong River and its tributaries support what is likely the largest inland fishery in the world, worth more than $2 billion annually, that over 60 million people rely on for daily food and livelihoods. Nearly 100 hydropower dams are planned for construction along the tributaries and main stem of the river’s 2,700-mile stretch.

In a , researchers from the ÌìÃÀÓ°ÊÓ´«Ã½, Arizona State University and others institutions that allows dam operators to generate power in ways that also protect — and possibly improve — food supplies and businesses throughout the Mekong River basin. The proposed solution, the first of its kind, can be applied to other large river systems around the world facing similar tradeoffs.

“One of the challenges in dealing with these systems and environmental change is the conversation is largely stuck in, ‘don’t build dams,’ or ‘yes, build dams,'” said , a UW assistant professor of aquatic and fishery sciences. “What this does say is, let’s try to find ways we can work together. This won’t solve all the problems, but let’s work to find solutions.”

The paper represents a first step in a large, multiyear project involving researchers across the UW and ASU campuses. Funded by the National Science Foundation’s , the project will use findings in the Mekong River basin as an example of how three critical issues — feeding people, generating energy and maintaining functioning ecosystems — can be addressed thoughtfully and progressively in the developing world.

Every summer in the Mekong River basin, monsoon rains flood the river and delta, increasing by six times the flooded area of Cambodia’s Tonle Sap Lake, the largest lake in Southeast Asia and frequently called the “heart” of the Mekong. The rise and eventual fall of the water triggers the migration of dozens of fish species, which spawn in the upper tributaries during low water. Fish larvae return to the lake on the next flood to grow and mature in its highly productive waters. This yearly pattern provides a critical source of animal protein, and an economy, for the people of Cambodia and other countries along the Lower Mekong.

But with new dams coming online soon, there is no basin-wide effort to coordinate how each dam’s release of water will impact the hydrology of the basin or fish, said , a UW professor of civil and environmental engineering and a collaborator on the project.

The goal of the project, involving researchers from fisheries, forestry, engineering, public health and the , is to gather information about how dam water flow interacts with fish, rice production and nutrition in this region and provide the most useful information to individual countries so that they can decide how best to operate their hydropower dams, he explained.

“We are trying to find a sweet spot for the many stakeholders, who often compete for resources, that can maximize the overall benefits in a way that doesn’t do too much damage to the environment, fish and livelihood of the region,” Hossain said.

One promising option is to use hydroelectric dams to mimic the flood of water from monsoon rains each spring that bring fish to the lake. The team’s algorithm, outlined in the Science paper, recommends long, low-flow periods punctuated by rapid flooding, which would allow dam operators to manage their power generation priorities while protecting fishing economies downstream.

The researchers found that seasonal periods of drought before the annual flood are crucial to producing abundant fisheries in the lake and surrounding streams. When the soil is dry, trees and plants grow, organic matter is produced and the soil is filled with nutrients. When floodwaters rush in, those nutrients are suspended in the water and fish are able to exploit them — drawing more fish to the feast, which in turn benefits fishers.

Holtgrieve, along with several UW colleagues, will study the flooding cycle in connection with the nutritional value of fish and rice, both staples in Southeast Asian diets, to help prioritize certain species and timing for harvesting the most nutritious food. Specifically, he will analyze tissue samples from 50 different fish species covering a range of habitats in the Mekong, measuring for beneficial fatty acids, vitamins and minerals, as well as for harmful elements like mercury.

“We as a society view fish as generally good for you,” Holtgrieve said. “This project recognizes that not all fish are the same in terms of their nutritional value.”

With the knowledge of which fish are the healthiest to eat, the researchers can work backward by figuring out what those fish like to eat, and then what flood and drought regime is most likely to produce those plants and organisms — controlled by dams releasing water — that produce more fish of high nutritional value.

Similarly, UW professors (civil and environmental engineering) and (environmental and forest sciences) will look at beneficial nutrients, such as zinc, and harmful contaminants, such as arsenic, in rice to measure whether the length of time that rice paddies are flooded makes a difference in the presence of these elements in the crop. Again, water releases from hydropower dams could be programmed to optimize for rice that is high in zinc and low in arsenic.

Hossain has used satellites to reverse engineer the blueprint of dam operations on about 20 dams in the Mekong region, and his those findings to dozens of the planned dams to try to predict their likely water releases and storages, and how they may impact the surrounding landscape.

“Satellites are immune to political boundaries on the ground,” he said. “Information is key, and I think it should be a fundamental right for everyone to know what’s happening with the water around them, but that’s not the case here, unfortunately.”

In other aspects of the project, (civil and environmental engineering) will help forecast future floods under hydropower and climate change scenarios, while (public health) will integrate the fish and rice nutrient data with information on the nutritional needs of the local population.

In addition to lab and field work, the researchers plan to visit the region, documenting in video and photos the personal stories from people who live in the Mekong River basin. They will also involve UW undergraduate students in a by accepting submissions for a based on stories from the Mekong.

The project will run for three years, and the researchers intend to share results along the way.

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For more information, contact Holtgrieve at gholt@uw.edu or 206-616-7041.

As the Earth warms, experts know the Columbia will change – they just don’t know how much or when.

ÌìÃÀÓ°ÊÓ´«Ã½ environmental engineers are launching a new study to try to understand how climate change will affect streamflow patterns in the Columbia River Basin. The team will look at the impact of glaciers on the river system, the range of possible streamflow changes and how much water will flow in the river at hundreds of locations in future years.

“Getting a new set of streamflow predictions factoring in climate change will help guide long-term decision-making for the Columbia River Basin,” said , a UW professor of civil and environmental engineering. He is leading the project with , UW researcher in civil and environmental engineering, and of Oregon State University.

The Columbia River’s headwaters are in the Rocky Mountains of British Columbia, and the waterway winds about 1,200 miles through Washington and along the border of Oregon before emptying into the Pacific Ocean. Hydroelectric dams provide cheap electricity to roughly three quarters of the Pacific Northwest’s population and help with flood control throughout the basin, particularly in the Portland metro area. It’s also an important waterway for migrating salmon, steelhead and sturgeon, and for navigation, irrigation and agriculture.

Changes in streamflow due to climate change could affect hydropower and flood control operations on the Columbia as well as fisheries management and future policy decisions, including a possible treaty renegotiation between the U.S. and Canada.

The UW researchers will use the most recent projections from the Intergovernmental Panel on Climate Change along with climate and hydrology models to come up with a dataset of streamflow predictions for Bonneville Power Administration, the U.S. Army Corps of Engineers and the Bureau of Reclamation, which jointly commissioned this study. The Bonneville Power Administration’s Technology Innovation Office, Oregon State University and the UW are funding the study, which leverages glacier model developments from a NASA-funded interdisciplinary science project.

“Hopefully, this study will be able to better bracket the uncertainty that exists methodologically between all these climate and hydrology models. If we want to be able to plan ahead on a 20- to 50-year timescale, we need to know what range of uncertainty to expect,” Nijssen said.

The impact that declining glaciers could have on the basin hasn’t fully been studied by U.S. scientists until now, though Canadian researchers recently started to look at their role. Glaciers are receding across the region and, as temperatures warm, they will continue to melt and erode. In 2005, glaciers covered about 420 square miles in the upper reaches of the Canadian Columbia Basin, or roughly 5 percent of that area. Twenty years before glaciers covered 490 square miles.

Melting glaciers put more water into the river system and boost its flow, but only for a period. This short-term boost could actually benefit the river – especially during low-flow periods in the drier summer months – but only in the short term. As the glaciers eventually disappear, perhaps as early as 2100, this added water will also disappear and further reduce already low summer flows, researchers say.

But the river’s yearly flows depend mostly on melting snowpack. Cooler spring and early summer temperatures can preserve mountain snowpack until the drier months, when water from melting snow is important to keep river flows high enough for migrating fish. As the climate warms, though, the timing of when that crucial snow melts and discharges into the river also is likely to change.

“The hydrology of the Columbia River basin is really driven by winter snow accumulation and melting in the spring and summer months. When it warms up, you change that balance,” Lettenmaier said.

The UW’s data could have policy implications for the Columbia River. Since 1964, a treaty between the U.S. and Canada has governed the river for hydropower production and flood control. But starting in 2014, each country can notify the other of an intent to terminate or modify this treaty. Changes to the treaty could be implemented as early as 2024.

“We want to have the best scientific information possible to help federal agencies and other regional stakeholders in long-range decision-making,” said Erik Pytlak, manager of the weather and streamflow forecasting for the Bonneville Power Administration. “With or without a treaty, climate change is coming. It will be beneficial for all of our partners and customers in the region to have an updated understanding of what climate change is doing to the region.”

The UW’s streamflow predictions will be publically available after the study is finished in three years. Similar studies are underway at Portland State University, also funded by Bonneville, and by climate scientists in Canada.

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For more information, contact Lettenmaier at dennisl@uw.edu or 206-543-2532 and Nijssen at nijssen@uw.edu.