To Breach or Not

ENVS 202 On-line Access

But First: Back to global warming:

The Yellow lines represent the +/- 2-sigma (2 standard deviations) surfaces about the data. The data are noisy, of course. Particularly the estimates that go back farther than 1600 AD.

These temperature estimates are based on chemical isoptope analysis of ice cores, sampled at various locations around the the world. The oxygen isotopic content of water (precipitation) is very sensitivie to sea surface temperature and this record is maintained when the water which falls remains frozen.

Since 1600, the average 2-standard range is approximately +/- 0.25 degrees above the mean this means that out of a period of 1000 years, we might expect 2 years to have an average temperature that is 0.25 degrees larger than the longer term mean temperture.

The 1998 average world temperature is approximately 1 degree C higher than the long term mean. Since 0.25 is already 2 standard deviations, then 1.0 is 8 standard deviations This is a huge signal!

Back to Fish:

Reactive Posture #1

Reactive Posture #2

Fish Farms

A few words about escaped salmon from fish farms:

The reason the issue of escaped salmon deserves our attention is that there are legitimate environmental concerns that result from a farmed fish escaping. In British Columbia, both Atlantic and Pacific salmon are being raised in farms and each of these two species poses unique risks once they do escape. For Atlantic, there's hybridization, which is basically Atlantic and salmon crossbreeding -- Atlantic and Pacific salmon crossbreeding. The other is predation and competition. This involves the Atlantic feeding on wild Pacific salmon, as well as other food supplies, and then the taking of space and the wild habitat in general.

Another major concern is spawning site disruption by Atlantic salmon. The stems from the fact that Atlantic salmon spawn later than Pacific salmon so there's a risk that they enter the same streams that the Pacifics have already spawned in and then they disrupt the eggs that the Pacific salmon have already placed. And also, Atlantic salmon mature faster than Pacific salmon, and so they have a competitive, or they give to the Pacific salmon a competitive disadvantage due to their smaller size. Another concern is colonisation of Atlantics in BC, which would have severe impacts on the wild stocks -- mainly because they would be using the same streams that wild Pacific stocks presently use to spawn. And finally, there is the issue of the spreading of diseases from the farmed salmon to the wild Pacific salmon.

Yanks are Ignorant

More than 50 percent of all fish traveling through the lower Snake River (up to 15 million) are diverted and collected for transport. The remainder are left in river. The majority of transported fish travel by barge. Trucks are used only early or late in the salmon migration season, when the numbers of fish are very low.

Despite all of the obstacles juvenile fish encounter, recent NMFS survival studies show that, with current mitigation measures, spring/summer chinook in-river passage survival is as follows:

Project Survival

The average survival through a dam and reservoir on the lower Snake River for juvenile salmon is in the mid-90th percentile (for example, spring/summer chinook passage through Little Goose Dam is 96 percent).

Lower Snake River Survival

Cumulative survival for juvenile salmon through all four dams and reservoirs is over 80 percent.

System Survival

Cumulative survival for juvenile salmon through all eight dams on the Columbia/Snake River System ranges from 45 to 60 percent.

Adult Survival

Cumulative survival for adult salmon through all four lower Snake River dams and reservoirs ranges from 88 to 94 percent. Per-project survival rate is 97 to 98 percent.

What is understood less is the indirect or delayed mortality of juvenile fish that may occur after they have passed Bonneville Dam. That mortality may have been caused by passing in-river through the hydrosystem, the series of eight dams and reservoirs from Lower Granite Dam to Bonneville Dam or from transportation of fish.

To Breach or Not

Ice Harbor Dam

Lower Monument Dam

Little Goose Dam

Lower Granite Dam

Another complex, often emotional issue, in which there is very little science to guide us:

Cost/Benefit Analysis is difficult and often driven by hidden agendas Save Fish vs. Lose of Jobs ?

Costs of dam breaching are difficult to estimate but are in the range of $1 billion and up.

Will it work?


Senator Larry Craig's viewpoint

Fisherman for Breach

Breaching would be bad for the Environment

The Primary Source

Four Alternatives Identified:


The CRI extinction analysis suggests that Alternative 4, while better than other alternatives, may still be inadequate by itself to reduce the risk of extinction of summer/spring chinook stocks to what NMFS proposed as suitable levels. The CRI analysis suggests that this alternative is likely to be sufficient for recovery of fall chinook and steelhead, but only if the survival below Bonneville Dam, as a result of this action, increases by at least 20 percent.

Under Alternative 4, there would be some negative effects on resident fish. In the short term, when the dams are breached, the rapid lowering of the reservoirs could strand some fish in shallow pools that will eventually stagnate. In addition, high turbidity and sediment in the water could cause trauma and injury, and low water levels could expose more fish to predators.

In the long term, the resident fish population will be altered, as some species will not thrive in the faster flowing river. Declines are expected in crappies, peamouth, pumpkinseed, bluegill, yellow perch, bullheads, and largemouth bass. Other species, including the chiselmouth, redside shiner, speckled dace, suckers, sculpin, white sturgeon, northern pikeminnow, bull trout, and smallmouth bass might benefit from natural river conditions.

A bit of a hint on the extra credit:

Dam breaching could result in significant movement of sediments. We estimate that 50 to 75 million cubic yards of existing sediments may be eroded and moved downstream. The majority of fine-grain silts would move quickly in the first few years following breaching. The coarser sands would move slowly downstream over 5 to 10 years. These existing and future sediments could move freely downstream toward McNary Dam and may cause some temporary adverse effects on food supplies for fish and bottom-feeding aquatic organisms. In addition, silt and sand now accumulated behind the dams could cause damage to pumps, valves, and other water system components.

Resuspension of sediments following dam breaching could result in exposing chemical contaminants that have been contained in reservoir sedimentation. Three chemicals are of concern total DDT, dioxin TEQ, and manganese. Only total DDT has any potential for affecting the biological system.

Power to replace Salmon Killers What are the options to finding 15,000 MW of power, continuously delivered, at 4-5 cents per KWH?:

Is there really an acceptable alternative?

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