There are several disadvantages to dams.

There are a number of disadvantages to existing dams:

• dams detract from natural settings, ruin nature's work
  
• dams have inundated the spawning grounds of fish
  
• dams have inhibited the seasonal migration of fish
  
• dams have endangered some species of fish
  
• dams may have inundated the potential for archaeological findings
  
• reservoirs can foster diseases if not properly maintained
  
• reservoir water can evaporate significantly
  
• some researchers believe that reservoirs can cause earthquakes
  

Recently listed endangered or threatened species of salmon include:

• Puget Sound chinook
• the Lower Columbia River chinook
• Upper Columbia spring chinook
• Lake Ozette sockeye
• Hood Canal summer chum
• Lower Columbia chum
• the Mid-Columbia steelhead
• and the steelhead and chinook in the Upper Willamette River

There are also disadvantages to building new dams:

• the reservoir created by the dam may inundate land, crops, cities and villages
  
• people may be displaced by the reservoir and have to find new homes
  
• the reservoir may cause instability of the hillsides
  

Each dam may stir up its own controversy because of some impact it has had or will have on its surroundings.

Glen Canyon Dam is on the Colorado River near Page, Arizona. Lake Powell, the reservoir behind Glen Canyon Dam, took 17 years to fill after the dam was completed in 1966. The dam provides hydroelectric power, water for irrigation, and recreation. In 1996, there was a proposal to drain Lake Powell. It's been quite the subject of controversy.

There are four dams on lower Snake River in Washington state: Lower Granite, Little Goose, Lower Monumental, and Ice Harbor. These dams allow navigation of the Lower Snake river by boat, create hydroelectric power, provide water for irrigation, provide recreation, and provide fish and wildlife ponds. These dams are in question because of the issue of salmon passage. The Remove or Decommission the Four Lower Snake River Dams (#) page is great; it gives viewpoints from the opposing sides. The US Army Corps of Engineers completed a study this year on the possibility of breaching the four dams and have decided that the dams will be breached. Now it is a matter of how they will be breached. Decomminssioning of the dams could increase power rates by $150 million a year. The Lower Snake River Dams are all over the news too -- see the Dam News:on the clean water act, on politics, and on endangered rivers.

They haven't even finished building this dam yet and it's the subject of enormous controversy. The Three Gorges Dam on the Yangtze River in China will be the largest dam in the world. It will help control flooding on the Yangtze and provide an enormous amount of power. Its reservoir will displace over 1 million people by the time it is filled. It is scheduled for completion in 2009. Check on a recent headline about the Three Gorges Dam in Dam News!

This is the first dam to be removed against the owner's will. The dam provided hydroelectric power for nearby towns in Maine. It was removed because it was blocking salmon and other fish passage. The Federal Energy Regulatory Commission is required to take environmental issues into account when renewing licenses for hydropower. They denied a new license to the Edwards Dam and it is being removed during the course of 1999.

What saves money, alas, kills salmon. from A River Lost by Blaine Harden, p. 25 What do you think?