Dam construction

Question 1

Where is the drainage basin for the columbia river?

Answer 1

• 360,000 m2
  spans across 7 states and 1 canadian province:
  Stretches across Oregon, Idaho, Washington, Canada and meets the see in the north pacific

Question 2

What is the significance of the columbia River Salmon?

Answer 2

• Economic: in 2005 Columbia River Salmon fishery is worth $142 million p.a. to local economy
• Cultural: ‘without salmon returning to our rivers, we would cease to be Indian People’.
• ecological: food webs/ salmon life cycle is Anadromous. There is a strong nutrient/ biomass link between ocean and river ecosystems
• Chum Salmon
• Coho salmon
• Pink Salmon
• Sock eye salmon
• Chinnok Salmo
• Steelhead

Prior to 1800 between 10-16 million salmon returned to the Columbia each year

Question 3

What are some of the memorable dams built along the columbia river?

Answer 3

• Rock Island 1932
• Bonneville- 1938
• Little Goose
• Ice harbour

Question 4

What are the benefits of the dam?

Answer 4

• HEP=- 87% of electricity production in washington state
• Irrigation- Water from Grand Coulee irrigrates ca 500,000 acres
• Flow regulations
• Flow control
• Transportation- Barges can navigate more than 450 miles
• Recreation- e.g. wind surfers from Seattle/ Portland

Jobs and Livlihoods depend on dams

Question 5

Negative impacts of dams on salmon?

Answer 5

• Alter flow regimes
• Loss of water through Irrigation
• Flooding salmon Habitat
• Impediment to fish
• Delayed Migration
• Increased predation and stress
• Damage to fish that pass through the turbines:
  >blade strike
  > Large pressure fluctuations
  > Shear forces
  > Turbulent waters disorientating fish

Question 6

What were some Historic precedents of English Mitigation?

Answer 6

1. The kings gap- a statue from the 12th C
   - English rivers must be kept free of obstructions so that a well fed 3 year old pig can stand sideways without touching either sides
2. The Magna Carta- a document King John was forced to sign in 1215
   - Contained a provision for removing weirs
   - To protect salmon for use as a public good through all of england
3. The salmon and freshwater Fisheries Act 1975

Section 22 - Prohibits the sale of salmon or trout between 31 August to 1 February.
Section 23 - Prohibits the export of salmon or trout unless previously approved by HM Customs and Excise.
Section 9 to 15 - It is the duty of the waterway owner that when constructing dams, screens or sluices to provide and maintain a facilitating fish pass for migrating salmon or trout. These must remain undisturbed and unfished by everyone. Fish passes must be altered by any way the water authority wishes.

Question 7

Historic mitigation in Eastern USA

Answer 7

• Between 17th and 19th centuries, mills were the main source of mechanical power
• Mill dams requried to divert water through the Mill system
• In addition to blocking water, they also blocked fished
• Complaints fro citizens accustomed to obtaining fish
• Early 18thC dams had to have openings to let fish pass during their migrations

Question 8

Western seaboard USA mitigation?

Answer 8

• Fish and Wildlife Coordination act, 1934
• Federal Power Act 1935
• Mitchell Act 1938
• Endangered Species Act, 1973
• The Pacific Northwest Electric Power Planning and Conservation Act, 1980

Question 9

How might we assess the impact of the dams on salmon population?

Answer 9

Need a baseline data for pre-dam era

• Search for historic data
• Use of an appropriate control site
• Conduct empirical studies
• Modelling

Question 10

What is the commercial salmon harvest trend?

Answer 10

• Between 1865 and 1977- salmon has significantly reduced

- Peaked late 1800s

Question 11

What are some significant Chinook trends?

Answer 11

Fluctuation in the amount of fish returning to Bonneville Dam since it was built 1938

• more than doubles to 900 (000s) by 2002
• Amount of escapees are reducing

Question 12

What do we know today?

Answer 12

History:

• Historic salmon returns: 10-16 million adults p.a.
• Chinook salmon runs on the columbia were the largest in the world

Today:
Runs have declined by 90% (around 1.5million returns in the 1990s)
- upturn in returns during late 1990s- early 2000s (ocean conditions? Improvements in management/ mitigation?)

Question 13

What are the factors that affect population status?

Answer 13

• Habitat
• Hydropower
• Harvest
• Hatchery
• Ecological conditions
• Climate change
• Predation
• Introduced bacteria

(these produce trends and abundance)

Question 14

What are the historic mitigation methods?

Answer 14

• Fisher ladders
• Concrete hatcheries
• Transportation

Question 15

What are the confounding factors that can seriously distort interpretation?

Answer 15

• Ocean conditions
• More dams constructed
• Improvements in mitigation/ Management.

Catch data alone can be misleading (we need catch / unit effort)