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About The Southwest Portland Post. (Portland, Oregon) 2007-current | View Entire Issue (May 1, 2012)
8 • The Southwest Portland Post Dear EarthTalk: How is it that dams actually hurt rivers? – Missy Davenport, Boulder, CO Dams are a symbol of human ingenu- ity and engineering prowess—control- ling the flow of a wild rushing river is no small feat. But in this day and age of environ- mental awareness, more and more peo- ple 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 FEATURES if they contribute much-needed renew- able, 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 Re- form 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 sup- porting river life of any kind. Also, water temperatures in dam reservoirs can differ greatly between the surface and depths, further complicat- ing 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 May 2012 harm downstream environments as well. Dammed riv- ers also lack the natural transport of sediment cru- cial to maintaining healthy organic ri- parian channels. Rocks, wood, sand and other natural materials build up at the mouth of the res- Dams have a deleterious affect on water quality and on fish ervoir instead of habitat and passage. Pictured is the world famous Hoover dispersing through Dam, built in 1936. (Photo courtesy of iStockPhoto/Think- the river ’s mean- stock) dering channel. tury ago. “Downstream of a dam, the river is While the U.S. government has starved of its structural materials and resisted taking down any major hy- cannot provide habitat,” reports HRC. droelectric dam along the Columbia Fish passage is also a concern. “Most system, political pressure is mounting. dams don’t simply draw a line in the No doubt all concerned parties will be water; they eliminate habitat in their paying close attention to the ecosystem reservoirs and in the river below,” and salmon recovery on the Elwha says HRC. River as it unfolds over the next few Migratory fish like salmon, which decades. are born upstream and may or may not CONTACTS: American Rivers, survive their downstream trip around, www.americanrivers.org; HRC, www. over or through a dam, stand an even hydroreform.org. poorer chance of completing the round EarthTalk® is written and edited by trip to spawn. Roddy Scheer and Doug Moss and is a reg- Indeed, wild salmon numbers in the istered trademark of E - The Environmental Pacific Northwest’s Columbia River Magazine (www.emagazine.com). Send basin are down some 85 percent since questions to: earthtalk@emagazine.com. the big dams went in there a half cen- Parker Realty, Inc. Mutnomah Village $395,000 Classic 1939 English-style Traditional – same owner since 1958. 3140 sqFt features 3 BR & 1.5 Bath, 2 car garage, hardwoods throughout, wood-burning fireplace & great views of the coast range. The home has an updated kitchen and newer furnace/AC but maintains all its Jeff Parker period detail, charm and character. This is the quintessential Your Neighborhood Multnomah Village property. MLS 12246556. Realtor Since 1980 The combination of fewer new listings and more closed sales has resulted in the lowest inventory of properties for sale in Portland since June 2007. If you’re thinking of selling contact us today for a free comparative market analysis. 503-977-1888•7830SW35thAve.,Portland,OR www.parkerrealtyportland.com Save 10% off ads for Dads and Grads 1/16 page or larger in the June edition Deadline is May 21 Call Don at 503-244-6933 or Harry at 503-244-4442 for details. Visit our online media kit at www.swportlandpost.com for sizes and rates.
