Science, Salmon and the Snake

Smolt to Adult Fish Ratios at Dams Along the Columbia and Snake Rivers

Smolt to Adult Fish Ratios at Dams Along the Columbia and Snake Rivers

The Snake is the Snake River, once one of the world’s preeminent salmon streams, famed for its chinook,sockeye and steelhead runs. Now those fish are an endangered species and at the heart of a complex struggle involving fish, water rights, hydroelectricity and, most of all, dam-foolishness.

One way to measure the health of an anadromous fish like salmon and steelhead is to count the number of you fish, smolts, moving downstream to the ocean and then count the number of adult fish that return to spawn. The smolts have a microchip inserted into their bodies that makes it possible to determine exactly which fish return. The ration of returning adults to departing smolts is called “SAR,” the Smolt-Adult Ratio. The established target SAR for the Snake River and its tributaries is 2-6%. Any lower than that and the population will be insufficient to preserve the species.

The graphic above requires a bit of parsing, but it captures the problem nicely. The green-shaded area is the Columbia River drainage. The blue-shaded area is the Snake River drainage below Hells Canyon Dam. The red lines through the rivers are dams. And you can see that is the damn problem. The fish can make it by the first two dams on the Columbia River to head up the Deschutes River, where the SAR is 6.9%, exceeding the target 2-6%. Fish can make it up the John Day River, past three Columbia River dams, where the SAR is measured at 3.5% for chinooks and 5.3% for steelhead. The fish can even make it up the Yakima River, past four Columbia River dams, in decent numbers, 2.2% for chinooks and 4.6% for steelhead.

The Lower Snake River Dams

The Lower Snake River Dams

But the four dams on the Lower Snake River are another matter. Above the Ice Harbor, Lower Monumental, Little Goose and Lower Granite Dams, the SAR falls to 1.6% for steelhead and 0.8% for chinook. That’s despite 20 years of effort, some $15 billion in expenses and five different salmon recovery plans. Plans that don’t involve removal of the have a failure rate of 100%.

The arguments for keeping the four dams have turned to ashes. We don’t need the power. The Pacific Northwest now has two and one-half times as much new, renewable energy generation up and running in the Pacific Northwest as all four Lower Snake River dams produce in a year—2,500 average Megawatts (aMW) versus 1,000 aMW, respectively. And energy savings have saved many times the production of these dams through conservation and efficiency.

The dams made Lewiston, Idaho, on the Idaho-Washington border, a port for barge traffic from the Columbia River. The Port of Lewiston was never all that successful, but since 2000, use of the lower Snake River to transport goods by barge has declined by more than 70%. Only grain is regularly shipped on the barges any longer, and most grain growers use rail. If barge traffic weren’t heavily subsidized by electrical consumers’ rates, barge traffic wouldn’t be close to competitive.

Now claims are being made that we need “reserve power,” but there is no data to support that claim. Right now, the Bonneville Power Administration sells that excess power to California; well, more accurately, BPA pays California to take it. The four dams are old, need maintenance and repairs. It doesn’t make any kind of economic sense to invest in infrastructure we don’t need. BPA doesn’t need the cost or the dams. The Pacific Northwest doesn’t need the electricity generated. California doesn’t want the power. The four dams are only going to get more expensive.

It’s time for the dams to be gone. Before the chinook, sockeye and steelhead are.