Tag: ecological assessment

Bristol Bay Blog, Part 3: A Future for Salmon?

Editor’s Note: This is the final installment in a three-part blog series on the Conservancy’s recent research at Bristol Bay, conducted to provide a risk assessment of the proposed Pebble Mine.

Can one of the world’s largest mines be built in the headwaters of the world’s largest salmon fishery without disrupting the ecosystem?

That’s a question that generates a lot of controversy for the Bristol Bay watershed.

“There is a lot of vilification and name calling, but we wanted to go past that and get the data,” says Dave Albert, director of conservation science for The Nature Conservancy in Alaska.

The Nature Conservancy in Alaska commissioned an ecological risk assessment to improve understanding of baseline conditions near the Pebble deposit as well as potential risks such a mine could pose to salmon.

The baseline studies showed that juvenile salmon are ubiquitous in headwaters near the Pebble deposit, including documentation of more than 100 miles of previously unknown salmon streams. It also documented the purity of the water. “This is about the cleanest water in the world,” says Albert. “It’s not distilled water, but it’s pretty darn close.”

The ecological risk assessment used a cutting-edge stream modeling system to investigate potential effects of large-scale mining facilities including open pit mines, a tailings impoundment and waste rock dumps on stream headwaters.

The model results indicate potential for significant negative effects, including up to 60 percent reduction in stream flows near the pit and contamination from waste rock that could exceed Alaska water quality standards. The giant waste rock piles generated by mining would require active pumping and water treatment; if these systems failed, the levels of copper in the river could rapidly exceed lethal levels for salmon.

According to the researchers: “Our study shows that while some of the flow and water quality changes brought about by mining could be ameliorated by ambitious mitigation measures and water management plans, severe water quality effects could result from even a brief failure of these systems.”

The proposed mine dwarfs all other mines in Alaska combined; because the ore exists in low concentrations preliminary designs developed by the mining company show the mine covering twenty square miles with a massive tailings impoundment. From preliminary information released by the company, this tailings pond would require perpetual mediation in an area known for active earthquakes.

“We haven’t seen a detailed mine and water management plan, but it would be difficult to envision a project of this scale that does not require active management, basically forever, to avoid contamination,” says Albert.

Full Article

Bristol Bay Blog, Part 1: Understanding Remote, Wild Waters

No fishing hyperbole: We caught something every other cast. At least.

Huge king salmon spawned in the river, but these were not the fish we were seeking. It was the fish following the king salmon. A host of species lined up downstream as the kings spawned, picking off eggs as they drifted past. We cast little beads that imitated the eggs and bam! Fish on!

Maybe it was a grayling or a large rainbow trout or a char. It didn’t matter: it was the greatest fishing of my life.

That was my first afternoon in the Bristol Bay watershed. The ensuing days there seemed like a parade of wonders: volcanic mountaintops, bears roaming lakeshores, hooking silver salmon in the rain, more rainbow trout and grayling and char.

Here’s the thing: We weren’t even there for the main event—the largest sockeye salmon runs on earth that taken together produce more sockeye salmon than the rest of the world. Combined.

Just last evening, we baked one of our Bristol Bay silver salmon fillets, and the memories came rushing back—memories of one of my finest adventures in a life filled with the pursuit of outdoor experiences around the globe.

And so I understand well the passion, the emotion, people feel for this place, especially when a gigantic mine is proposed right in the midst of it.

The Bristol Bay watershed is located in southwestern Alaska, a mind-bogglingly wild expanse of rivers and streams that covers 58,000 square miles. It has always been best known for its salmon population and the subsistence, commercial and recreational fisheries it supports.

Lately, though, Bristol Bay has received even broader attention, with the proposed mine most commonly known as the Pebble Mine. As it happens, Bristol Bay also sits atop the largest copper and gold deposit on earth. By most estimates, Pebble Mine would be the largest copper mine in North America and one of the largest in the world.

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