Exercises for the Smolts Model

Use the slider controls to eliminate all sources of mortality in the model. Then run the model to verify that the 10 million hatchery smolts will reach the ocean within 30 days under average flow conditions.

Using a hand calculator, estimate the number of smolts that would reach the ocean if turbines were the only source of mortality. (The mortality at each dam is 15% and there are 8 dams on the river.) Set the turbine survival fraction at 85%; set the bypass fractions to zero; and run the model. You should see 2.725 million smolts reach the ocean.

Assume that the coming hydroelectric year will experience medium flows. You are asked to recommend either a modest draw down or 100% barging at Lower Granite. (But you can’t recommend both.) Which policy would allow more smolts to reach the ocean?

Assume that the year will experience medium flows, and you are asked to recommend either a major draw down or 100% barging at Lower Granite. (But we can’t do both.) Which would you recommend to allow more smolts to reach the ocean?

Repeat the analysis from the 3rd and 4th exercises with low flow conditions. Remember you must recommend either a draw down or barging, but not both. Which would you recommend?

Repeat the analysis from the 3rd and 4th exercises under high flow conditions. Would you recommend barging or a draw down?

7. Sensitivity Test: Latent Mortality

Lower the latent deaths fraction from 51% to 25% and repeat the analysis from the 3rd exercise. Then raise the fraction from 51% to 75% and repeat the analysis. Would you change your recommendations from the third exercise based on the sensitivity tests?

The Northwest region has long experience with barging. More recently, it has begun testing the feasibility of draw downs. The draw down tests are vigorously opposed by groups that advocate "regular river operations." They claim that there is no reason to experiment with draw downs when we have barging. Does your analyses shed any light on why the region would be interested in both barging and a draw down?

Researchers at INEEL, the Idaho National Engineering and Environmental Laboratory, are working on a new turbine design that would lower smolt mortality. Let’s suppose they succeed in reducing the turbine mortality from 15% to 7%. Now, let’s suppose we have initial funding to install the new turbines at ONE of the dams. You might install them at Lower Granite, at Bonneville or at any of the dams in between. Which dam would you select if your goal was to install the new turbines where they would deliver the most benefit to the smolts?

Expand the model by introducing a new turbine survival fraction at the dam to receive the friendly turbines. Then use the model to check your answer to the previous exercise. You may assume medium flow conditions, regular river operations and no barging.