Review It
Complete the activity below to review how to identify claims, evidence and reasoning in a text. Remember to think about how the evidence supports the claim. In addition, pay particular attention to how the author uses reasoning to explain how the evidence supports the claim.
Read the “Environmental Risks To Consider” section from the article ”California tries one solution to water problems – treating seawater”opens in new window.
Environmental Risks To Consider
9 Many conservation groups are critical of desalination. They argue that it comes not only with unjustifiably high costs, but with a lot of environmental risks as well.
10 Based on its cost and the environmental damage it causes, desalination should always be last among possible choices, environmentalist Conner Everts said. “It’s kind of an engineer’s dream, but there’s a lot of challenges to it.”
11 Desalination involves two basic stages: seawater intakes and outfalls.
12 Desalination plants operate by drawing in seawater. Unless that intake is carefully designed, it can harm marine life. Reverse-osmosis filters are so fine that they allow only water to pass — everything else entering the desalination plant is killed.
13 One solution is fish screens, similar to those widely used at water-treatment plants along California rivers. Carlsbad, for example, will use fish screens with tiny openings. These will strain out at least 95 percent of small fish, but only 20 percent of organisms. The remaining 80 percent of tiny organisms — including fish eggs — will be sucked into the desalination plant and killed. Many small lifeforms that fish depend on for food would be destroyed.
14 The desalination industry worldwide largely favors screened intakes, despite the damage they cause. They are cheaper to build than the alternative favored by the water board — so-called subsurface intakes.
– Newselaopens in new window, December 4, 2014
