Field Trip: Dam studies on snow and ice

The proposal to build a Hydroelectric Dam on the Susitna River set wheels in motion that are becoming more and more visible as spring break-up approaches. The Alaska Energy Authority has received approval to undertake 58 studies on the river, nearly all of which will be performed by contractors from around the state. KTNA’s Lorien Nettleton got a chance to see science in action, 25 miles north of Talkeetna on the frozen Susitna, and has this report.

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Break-up is coming, and the annual opening of alaskan waters is just around the corner, and though the Susitna river is still covered in snow and ice, signs of change are everywhere.

The proposed Susitna Watana Hydroelectric Dam would change the way the river behaves. By releasing water during the winter months for electric generation, the now-quiet environment would have fluctuating water levels year-round, disrupting the normal freeze-up processes. Most people think it is unlikely that the river would freeze at all, meaning a dramatic change to the ecosystem. Beginning last year, a whole slew of studies began and will last through 2014, in an attempt to quantify what will change in the ecosystem, and how much it will change. Based on the outcome of some 58 studies, the Alaska legislature will have to decide if the benefits of electric generation outweigh the toll on the environment.

Mike Wood has been assisting scientists with their research of the river in its winter-time environment. He started in the fall, as studies were being established, and the data collection lasts through the winter. Wood has lived along the river for more than a decade, and his knowledge of the river from traveling on it in summer and winter has given him a unique perspective.

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Traveling by boat or showmachine, Wood has helped scientists place instruments in the river that  capture data that will provide insights into the river’s ecology. At one site 25 miles north of Talkeetna, Wood helped install instruments that log temperatures, register currents, measure sediment load, and take pictures of the surface cover every hour. He’s getting a close-up view of how some of the studies are being conducted.

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One of the nearby study sites is in a slough that stays open almost all year, due to upwelling groundwater. It was here Wood says scientists found a kind of nursery for chinook minnows. It was just one example of myriad unique features that are influenced by seasonal changes in water level. The circumstances surrounding the slough as prime habitat seemed to me to be unpredictable, but Wood gained insights in to how it all came together while working with the scientists.

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The conditions that influenced the way the river froze in 2012 were different from years prior, and future freeze-up conditions are likely to be equally predictable. The studies which were began last winter and will continue in to next year propose to identify and quantify the processes. Even after ten years, Wood says knowing what the river will do is still at times a guessing game.

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The traffic on the river and surrounding areas will increase dramatically as summer field season begins, with studies taking place along the length of the Susitna. While two years may seem like a short amount of time to gather a tremendous amount of information, it will nevertheless make the Susitna one of the most studied rivers in Alaska, Wood says.

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