TEAR DOWN THIS WALL?: Dams have a deleterious affect on water quality and on fish habitat and passage. Indeed, wild salmon numbers in the Pacific Northwest's Columbia River Basin are down some 85 percent since the big dams were built there a half century ago. Pictured: the world famous Hoover dam, built in 1936.
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Dear EarthTalk: How is it that dams actually hurt rivers?—Missy Davenport, Boulder, Colo.
Dams are a symbol of human ingenuity and engineering prowess—controlling the flow of a wild rushing river is no small feat. But in this day and age of environmental awareness, more and more people are questioning whether generating a little hydroelectric power is worth destroying riparian ecosystems from their headwaters in the mountains to their mouths at the ocean and beyond.
According to the non-profit American Rivers, over 1,000 dams across the U.S. have been removed to date. And the biggest dam removal project in history in now well underway in Olympic National Park in Washington State where two century-old dams along the Elwha River are coming out. But why go to all the trouble and expense of removing dams, especially if they contribute much-needed renewable, pollution-free electricity to our power grids?
The decision usually comes down to a cost/benefit analysis taking into account how much power a given dam generates and how much harm its existence is doing to its host river’s environment. Removing the dams on the Elwha River was a no-brainer, given that they produced very little usable electricity and blocked fish passage on one of the region’s premiere salmon rivers. Other cases aren’t so clear cut.
According to the Hydropower Reform Coalition (HRC), a consortium of 150 groups concerned about the impact of dams, degraded water quality is one of the chief concerns. Organic materials from within and outside the river that would normally wash downstream get built up behind dams and start to consume a large amount of oxygen as they decompose. In some cases this triggers algae blooms which, in turn, create oxygen-starved “dead zones” incapable of supporting river life of any kind. Also, water temperatures in dam reservoirs can differ greatly between the surface and depths, further complicating survival for marine life evolved to handle natural temperature cycling. And when dam operators release oxygen-deprived water with unnatural temperatures into the river below, they harm downstream environments as well.
Dammed rivers also lack the natural transport of sediment crucial to maintaining healthy organic riparian channels. Rocks, wood, sand and other natural materials build up at the mouth of the reservoir instead of dispersing through the river’s meandering channel. “Downstream of a dam, the river is starved of its structural materials and cannot provide habitat,” reports HRC.
Fish passage is also a concern. “Most dams don’t simply draw a line in the water; they eliminate habitat in their reservoirs and in the river below,” says HRC. Migratory fish like salmon, which are born upstream and may or may not survive their downstream trip around, over or through a dam, stand an even poorer chance of completing the round trip to spawn. Indeed, wild salmon numbers in the Pacific Northwest’s Columbia River basin are down some 85 percent since the big dams went in there a half century ago.
While the U.S. government has resisted taking down any major hydroelectric dam along the Columbia system, political pressure is mounting. No doubt all concerned parties will be paying close attention to the ecosystem and salmon recovery on the Elwha as it unfolds over the next few decades.
CONTACTS: American Rivers, www.americanrivers.org; HRC, www.hydroreform.org.
EarthTalk® is written and edited by Roddy Scheer and Doug Moss and is a registered trademark of E - The Environmental Magazine ( www.emagazine.com). Send questions to: earthtalk@emagazine.com. Subscribe: www.emagazine.com/subscribe. Free Trial Issue: www.emagazine.com/trial.
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12 Comments
Add CommentUnbelievable, Can't do Nuclear Power cause it will kill us all, Can't do coal power cause it will heat the Earth, Can't do solar power cause the space required takes up endangered species habitat, can't do wind power cause it kills birds or ruins your view, can't use natural gas cause you frack for it, and now, hydro power is bad for fish, can't do that.
Reply | Report Abuse | Link to thisI think if you come up with a "You can't do that!!", you need to tell us a viable alternative. How exactly are we supposed to generate electricity for ourselves so everybody can use it? Or are we just supposed to live in the Stone Age? That's really what you want isn't it, so everyone can be CAVE people just like you! CAVE, as in Citizen Against Virtually Everything.
can build more energy efficient machinery, can be more energy saving household appliances, can build 50 miles per gallon cars, can make solar, wind and other turbine power far better, can invest a fraction of the money that fission nuclear costs because of military needs into other types of nuclear, can, can, can... but the industry is only interested in profit at the smallest cost possible and politicians are ... (see Romney and his remarks on half the US population for clues) - OTOH if you are a Romney fan, delete half the US population and you're left with only the rich who can afford big cars, polluting planes, inefficient housing, exorbitant energy prices, no science. The solution to your question is then to get rid of half the US population, those not voting Romney, and all your problems are solved.
Reply | Report Abuse | Link to this2. jctyler
Reply | Report Abuse | Link to thisin reply to ChazInMT
At what cost and impact to the environment? This has nothing to do with politics (BTW here is a little secret: they are all equally corrupt and more interested in their job than making things better) and everything to do with technology and cost. The government can keep supplying subsidies to wind and solar (and oil/gas and coal for that matter) and nothing will change. I say stop all subsidies for starters. Then we will see the real cost of each form of energy.
Unfortunately for wind and solar they will crater on cost alone. Then we can discuss the negative health and environmental implications and let the people (who are allegedly in charge of the government) decide what they want to do. We can choose to continue to burn cheap fossil fuels and nuclear and accept those implications or we can go with the renewables and accept those implications. Either way we have to choose how we wish to balance our energy needs and cost is going to be a major factor.
as a dependent, your comment is worthless
Reply | Report Abuse | Link to thisMore evidence this magazine/site is a thinly disguised outlet for the progressive political movement. Occasionally, an inarticulate novice soils the linens like this. It must be embarrassing to the tenured members.
Reply | Report Abuse | Link to thisIf the US were so technologically advanced, why are their cars still using twice as much as European cars where these are even still the better ones too? (One of the candidates idea of saving energy is building an elevator for his cars into his home. So they don't have to drive up. Get it?)
Reply | Report Abuse | Link to thisIf the US were so scientifically savvy, why are they still using ten times more energy than the average of the rest of the world?
If the US were so intelligent, why are your cities full of grotesquely obese people? The resources wasted for those bloated aliens alone would be enough to feed the whole of Africa.
Is this to do with politicians? Yes. They make the rules. And if one candidate thinks one half of the population is useless then he doesn't have a clue what the working class is. And if he doesn't know that he doesn't know who builds the car he drives. But then he wouldn't care less because it is a well-documented fact that he made his millions by killing US jobs. A candidate who doesn't have the brain to understand the value of "mass" does not understand science. A candidate who would become president and doesn't undersand neither mass nor science would certainly not further mass nor science. But, and give credit where credit is due, he'd be good at helping his buddies do their tax forms. The rich get richer, the poor get poorer? Where's the sociological science in that?
And someone like that is very unlikely to understand the environmental challenges that face the US more than any other first-world country.
We'll be still feasting in Europe when you'll have to unscrew the light in your fridges to save electricity. And look better too. <g>
All said and done POWER IS THE NEED OF THE HOUR both for Developed and developing Countries. Critics say Nuclear power is dangerous, Coal power polluting, Big dams not safe etc. Then how to meet the growing demand of power. Coal, Nuclear, Major Hydro electric power all have a role in the energy mix.
Reply | Report Abuse | Link to thisDr.A.Jagadeesh Nellore(AP),India
E-mail: anumakonda.jagadeesh@gmail.com
how about inserting an intelligent sentence here and there in your comment instead of just typing some general political slogan that is utterly meaningless in the context?
Reply | Report Abuse | Link to thisyou don't have ideas, you only have slogans.
and make no mistake, you're part of that half for which your favorite candidate has only contempt.
Naw, if you can't add anything intelligent, creative or at least interesting to read to the discussion, your comment is simply worthless.
OTOH, you're not alone to overrate the value of your contribution.
Nobody says that all the present energy sources need to be stopped at once. But they need to be phased out. And you can only do that if you are preparing and phasing in replacement. Which is what Europe, India and China are doing and where the US are badly lagging.
Reply | Report Abuse | Link to thissearch "world map energy consumption"
<This has nothing to do with politics>
Reply | Report Abuse | Link to thisWho makes the laws? It's ALL about politics.
<they are all equally corrupt>
I don't think that either candidate is corrupt, I simply believe that in view of the facts and how they each made their money, the one is trying to make things better for everybody and the other is trying to make things better for himself.
<everything to do with technology and cost.>
Yes. If gas cost what it really costs = including environmental cost, Detroit would within two years build cars that run on one fourth the petrol of today.
<The government can keep supplying subsidies to wind and solar (and oil/gas and coal for that matter) and nothing will change.>
Agreed. Again, if energy cost what it really costs, nuclear energy would be four times as expensive and alternative energy would be comparatively cheap. In that case, the industry would do the same thing as Detroit.
<stop all subsidies for starters, then we will see the real cost of each form of energy>
fully agree. If 10% of those anti-social subsidies went into research...
Niagara Falls has a hydroelectric system that does not hinder the river.
Reply | Report Abuse | Link to thishttp://www.scientificamerican.com/article.cfm?id=existing-technologies-could-cut-vehicle-fuel-use-in-half
Reply | Report Abuse | Link to thisis what I said