Susitna River Q & A

Alaska is a land that provides. Its unrivaled wealth of resources offers sources of energy, minerals, fiber and fish. A set of questions first voiced by Alaska Gov. Jay Hammond (and Nature Conservancy trustee) presents one approach to evaluating development proposals in Alaska:

  1. Is it environmentally sound?
  2. Do the majority of Alaskans want it?
  3. Can it pay its own way?
  4. Does it meet our constitution’s mandate that it provide maximum benefits to the people?
In the spirit of Hammond’s made-for-Alaska standard, The Nature Conservancy in Alaska is committed to a comprehensive, science-based review of the proposal to develop a dam on the Susitna River. If large-scale hydropower development is to occur in Alaska, how do we ensure long-term conservation of salmon and their habitat? When the value of nature’s ecosystem services is included, do the economics pencil out? And how would a dam affect Alaska communities? These and other questions demand thoughtful answers.

This is why we’ve recently welcomed a fellow Conservancy freshwater scientist whose work focuses on the effects of hydropower on rivers and the species that depend on them. Tara Moberg, a former biologist with the federal Bureau of Reclamation and a newly appointed board member of the Low Impact Hydropower Institute, talked with us about her initial investigations into the Susitna River hydropower proposal.

The fact that Alaska’s rivers are still their own “hatcheries” – producing incredible runs of five species of wild salmon – is one not to be overlooked. - See more at: fact that Alaska’s rivers are still their own “hatcheries” – producing incredible runs of five species of wild salmon – is one not to be overlooked.
"We can’t develop hydropower in the same way that we have and expect different results."

- Tara Moberg, freshwater scientist for The Nature Conservancy

How do we begin to understand the effects of a large dam on a river like the Susitna?

Tara Moberg:

Alaskans have a powerful opportunity. The decision of whether or not to meet renewable energy needs with the proposed dam can benefit from what we’ve learned from dozens of similar projects around the world – several in our backyard.

I really think it calls for a broader dialogue about the true cost over the life of the proposed dam – from the traditional costs like construction and operation to include the environmental, social and economic costs we didn’t anticipate or consider 50 to 100 years ago.

What has our nation learned about the effects of hydropower on salmon runs?

Tara Moberg:

We’ve learned that hydropower development, specifically large mainstem dams, can devastate salmon populations. In addition to physically blocking spawning migrations, we know that large dams and reservoirs trap gravel and cobble that are critical to maintaining instream fish habitat. We also know that operations associated with hydropower, such as peaking, can change streamflows in a way that interrupts migration cues, reduces spawning habitats, changes ice break up and causes wetting and drying of the stream margins used by juveniles as nursery habitat. Those are just a few of the direct impacts that we’ve observed. There are dozens of indirect impacts.

We can’t develop hydropower in the same way that we have and expect different results. I think people would easily agree with that, but it isn’t necessarily what we see in practice.

Are there 21st century approaches to hydropower that are considered less harmful to salmon?

Tara Moberg:

Absolutely. What I see as one of our most valuable renewable resources is human ingenuity. These are solvable problems. We can meet renewable energy needs and minimize short and long-term impacts if we have the motivation and flexibility for creative solutions.

Historically, the most significant unintended consequences of large-scale hydropower are related to a dam’s location, its presence as a barrier, its influence on sediment transport and the operational influence on the downstream flow regime. There have been innovations that attempt to address each of these problems. There are siting tools, like the Conservancy’s Hydropower by Design, to select locations that minimize impacts. There are infrastructure designs that take advantage of a river’s energy potential while minimizing or avoiding the presence of a barrier to migrating fish and sediment transport. There have also been dozens of large hydropower dams that have changed their historic operations to restore components of the natural flow regime. As part of my fellowship with the Alaska program, I’ll be summarizing cases where these innovations have been successful, where they haven’t and their applicability to the proposed project.

Hydropower is considered a renewable energy source, but can hydropower be sustainable?

Tara Moberg:

This is a great question, as it raises an important distinction for all renewable energy sources. I believe that renewable energy sources, like wind, solar, tidal and hydropower, can be developed in a sustainable way. But, their sustainability hinges on intentional siting, design and management coupled with a decision process that accounts for local and global interests.

Specific to hydropower, The Nature Conservancy has been working with partners globally to develop decision tools and processes, like the Hydropower Sustainability Assessment Protocol, in pursuit of that goal.

How is the Conservancy contributing to the conversation about the Susitna hydropower proposal?

Tara Moberg:

The Conservancy is working to synthesize best available science, technology and global expertise. We’re committed to providing that information, in a digestible format, to all stakeholders – including local, state and federal governments, community organizations and the Alaska Energy Authority.

We hope this makes the conversation more accessible. For example, there are 58 studies happening under the Federal Energy Regulatory Commission licensing process. But each one of those is happening on a piece of the larger question of how the dam would impact the ecosystem – and the resulting social and economic implications of that impact. The Nature Conservancy’s own ecological risk assessment parallels this effort and offers a logical framework for how to use that information in making decisions.

How does climate change affect how we evaluate hydropower proposals, specifically in Alaska?

Tara Moberg:

In Alaska’s glacially fed rivers, we know the changing climate will play a significant role in the timing, volume and predictability of stream flows. The value of any hydropower investment relies on these factors. The relative social, economic and environmental impacts also rely on these factors. We have existing models that can predict these changes, within a range. Without exception, this should fundamentally and technically influence how we evaluate hydropower.

It seems everyone in Alaska has a salmon story to tell. What’s yours?

Tara Moberg:

It’s my first. I was fishing a tributary to the Susitna. Walking up the river margin, you could count hundreds of salmon within eyeshot. Bank to bank, heads pointed upstream, generally holding their formation, with flashes of red occasionally charging up then dropping back. I grew up fishing and had never experienced anything like it.

The lure was only about 20 feet away from me when a salmon broke rank. The salmon shot upstream, then downstream. I was falling on the banks trying to stay with it. I eventually got it in and was beside myself. It was gorgeous. I was in awe at this spectacular 24-plus-inch chum salmon.

When the guides returned to pick me up, I proudly held up my catch. They started cracking up. I didn’t get the joke. ‘Alaskans don’t eat chum salmon,’ they said – only a slight exaggeration. That didn’t stop me from filleting it and preparing it for dinner – chum cakes and a lemon dill sauce. I shared it with my hosts, who kindly entertained the invite.

For me it punctuated the bounty of ‘the last frontier.’ From that perspective, it’s easy to see how we can forget that these resources have bounds.

As a former Bureau of Reclamation biologist, you have a unique perspective. What closing thoughts might you offer to Alaskans?

Tara Moberg:

I have two thoughts and one expression of gratitude. First, I’ve spent the last ten years working on highly engineered large rivers from the Colorado to the Susquehanna. On these systems, once thriving fish populations are now marginally sustained by some combination of ladders, lifts, truck transport and hatcheries. The fact that Alaska’s rivers are still their own “hatcheries” – producing incredible runs of five species of wild salmon – is one not to be overlooked. It’s one of the few places in the world where that is still the case – where there is still an opportunity to tinker intelligently.

Second, if there is one enduring impression from my time in Alaska, it is the unique connection between people and place. Coffee shop conversations range from snowpack science to tips on the ripeness of blueberries along the Denali Highway – from listing rivers where the silvers are running to detailing river reaches where grizzlies were close on their tails. Alaskans have maintained an awareness of their role and relationship with the landscape.

From my perspective, this connection means you are uniquely positioned to envision and shape a lifestyle and landscape that meets your needs without compromising the quality of life for others – present or future, human or salmon.

I encourage Alaskans to be part of the conversation, if they aren’t already. And I thank Alaskans for their thoughtful stewardship of an incredible salmon resource.


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