Many of the dams in the eastern U.S. were originally built for water

Question

Many of the dams in the eastern U.S. were originally built for water diversion, agriculture, factory watermills, or other purposes that are no longer useful. Because of the age of these smaller dams, most are now at risk for catastrophic failure or partial failure. In addition, these dams block eastern anadromous fish runs, such as those for Atlantic salmon and American shad, and prevent important sediments from reaching estuaries.

In the western U.S., most of the dams are larger projects that were built for agricultural water diversion in arid country, with hydroelectric power generation as a significant side benefit. As in the eastern U.S., the dams in the Pacific Northwest and California block passage for western anadromous fish species such as Pacific salmon and steelhead trout. Likewise, fish ladders and other passage facilities have been largely ineffective in mitigating the negative effects on local populations such as Pacific salmon, although they have worked somewhat for steelheads.

Because of these negative effects and the questionable usefulness of many dams today, widespread debates over dam removals are taking place across the U.S. While agricultural water diversion and clean, alternative energy sources are important, the safety concerns, ecosystem issues, and management expenses associated with many dams make removal the smarter option in most cases. Managers at the Bureau of Land Reclamation, which oversees most U.S. dams, need to focus on removing most of the smaller, outdated dams in the East and some of the “worst offenders” in the West.

One example of a large western dam that should clearly be removed is the 710 ft. Glen Canyon Dam in Arizona. The negative effects it has on the water quality and riparian habitat of the Colorado River in Grand Canyon National Park are nearly catastrophic. The lake formed by the dam has eliminated more than 160 miles of habitat for endangered Colorado River fish species. The reservoir also loses more than 6 percent of the total annual flow of the Colorado River to evaporation and seepage. With its size and prestige, removal of the Glen Canyon dam would be a monumental and unprecedented step toward improving much of the devastation caused by outdated and now unnecessary dams across the U.S.   1 
  Solution 
Explanation: In the passage, the author gives all of these as a reason except for (A). He references power generation as a positive side benefit of dams, not as a reason to remove them. For (B), the lack of usefulness and necessity of dams is given as a major reason in multiple places in the passage. For (C) and (D), the management expenses and safety concerns of the dams are given explicitly as reasons to remove them in the 3rd paragraph. For (E), the effect on estuaries is discussed in the first paragraph and then this is referenced as a “negative effect” (first line of 3rd paragraph) and a reason to remove dams. Correct answer is (A). 
 1. According to the passage, each of the following constitutes a reason to remove a dam EXCEPT:

A the increased power generation of that dam. 
B the limited usefulness of that dam today. 
C the operating costs of that dam. 
D the decreased safety of that dam. 
E the negative effects of that dam on estuaries.

2 
 2. The author most probably believes that:

A. protecting certain fish species is the most important reason for removing dams. 
B. removing dams in the eastern U.S. is more important than removing dams in the western U.S.. 
C. dams do not play any important role in today’s modern society. 
D. the Glen Canyon dam is both outdated and unnecessary. 
E. all dams in which important ecosystems are affected should be removed.

3 
 3. It can be inferred from the passage that, in comparison to western dams, eastern dams:

A. cause more problems in blocking fish habitat. 
B. are used more often for powering factories and mills. 
C. are generally smaller in size and scope. 
D. are generally older in age and less useful. 
E. are more likely to fail catastrophically.

4 
 4. Which of the following best describes the role of the last paragraph in relation to the passage as a whole?

A. It summarizes the main position of the author. 
B. It provides an exception to the author’s viewpoint. 
C. It exemplifies one important goal of the author. 
D. It highlights the difficulties of the author’s goals. 
E. It provides a broader example of the author’s position.

5 
 5. Which of the following can be inferred from the passage:

A. steelhead trout have been less affected by dams in the west than Pacific salmon. 
B. most dams in the U.S. were built for agricultural water diversion. 
C. fish species are more affected by dams than any other species. 
D. most of the smaller dams in the U.S. are at risk for partial or catastrophic failure. 
E. no U.S. dam as large and prestigious as the Glen Canyon dam has ever been removed

6 
 6. According to the passage it is likely that:

A. fish ladders and other passage facilities have been generally ineffective in eastern dams. 
B. most eastern dams will soon suffer catastrophic or partial failure. 
C. very few new dam projects will be approved in both the eastern and western U.S.. 
D. other large reservoirs formed by large western dams suffer from evaporation and seepage issues. 
E. the Glen Canyon dam blocks passage for many western anadromous fish species.

7 
 7/ The primary purpose of this passage is to:

A. discuss an important and controversial environmental issue
B. argue that the Glen Canyon dam should be removed.
C. advocate a particular position regarding a controversial issue.
D. propose a new solution for addressing dam removal.
E. question the position of those who support dam projects.

rishabhmishra · Accepted Answer

Reason for eliminating options
1. 1/ According to the passage, each of the following constitutes a reason to remove a dam EXCEPT:

A the increased power generation of that dam. correct 
B the limited usefulness of that dam today. it was used in 1st passage  
C the operating costs of that dam. 3rd passage management expenses  
D the decreased safety of that dam.  3rd passage   
E the negative effects of that dam on estuaries.  in all over 
2. 2/ The author most probably believes that:

A protecting certain fish species is the most important reason for removing dams.  their is nothing written about most important reason its one of the reason

B removing dams in the eastern U.S. is more important than removing dams in the western U.S.. again nothing written about which is more important

C dams do not play any important role in today’s modern society. may be in eastern but nothing written about western dams

D the Glen Canyon dam is both outdated and unnecessary. Correct

E all dams in which important ecosystems are affected should be removed. all   make this incorrect as only eastern and western dams are mentioned  
3. 3/ It can be inferred from the passage that, in comparison to western dams, eastern dams:

A cause more problems in blocking fish habitat.  nothing about which causes more problem 
B are used more often for powering factories and mills. again nothing about which one is more useful 
C are generally smaller in size and scope. correct 
D are generally older in age and less useful. nothing about which one is older or younger 
E are more likely to fail catastrophically.  nothing about which one is more likely

4. 4/Which of the following best describes the role of the last paragraph in relation to the passage as a whole?  
last passage is a pure example so rest can be eliminated

A It summarizes the main position of the author. eliminated as it is an example  
B It provides an exception to the author’s viewpoint.  nothing exceptional just example of one dam which is mentioned above 
C It exemplifies one important goal of the author.  correct its an example and 1 important goal is its a big task to remove such a dam 
D It highlights the difficulties of the author’s goals.  Nothing about difficulties of author 
E It provides a broader example of the author’s position.  nothing about broader or narrow possition

5. 5/ Which of the following can be inferred from the passage:

A steelhead trout have been less affected by dams in the west than Pacific salmon. can be kept i am confused in this one

B most dams in the U.S. were built for agricultural water diversion.  nothing is given about it
 
C fish species are more affected by dams than any other species.  nothing about other species so don't know about them

D most of the smaller dams in the U.S. are at risk for partial or catastrophic failure.  can be kept this can be removed because of most as extreme word

E no U.S. dam as large and prestigious as the Glen Canyon dam has ever been removed  can be kept correct

6. 6/ According to the passage it is likely that:

A fish ladders and other passage facilities have been generally ineffective in eastern dams. correct

B most eastern dams will soon suffer catastrophic or partial failure.  we don't know about most so eliminated

C very few new dam projects will be approved in both the eastern and western U.S..  don't know about new

D other large reservoirs formed by large western dams suffer from evaporation and seepage issues.  don't know about others

E. the Glen Canyon dam blocks passage for many western anadromous fish species.  nothing given anything like that .

7. 7/ The primary purpose of this passage is to: 
 tone is neural

A discuss an important and controversial environmental issue  can be kept this can be removed as it is more general 
B argue that the Glen Canyon dam should be removed.  negative removed 
C advocate a particular position regarding a controversial issue.correct  this one is more accurate as whole passage is about dam which is more one particular issue 
D propose a new solution for addressing dam removal. no new solution is provided 
E question the position of those who support dam projects.    nothing questioning eliminated 
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arvind910619 · Answer

Here is question 4 with all the options.
4/Which of the following best describes the role of the last paragraph in relation to the passage as a whole?

A It summarizes the main position of the author. 
B It provides an exception to the author’s viewpoint. 
C It exemplifies one important goal of the author. 
D It highlights the difficulties of the author’s goals. 
E It provides a broader example of the author’s position

OA is C.

Last passage describes a large dam and why it should be removed?. Last paragraph gives more details about why glen canyon dam should be removed.
Clearly C is the only answer possible as from fist paragraph the theme of the article is that outdated dams must be removed. To justify the position the author gives one example.

arvind910619 · Answer

Here is question 4 with all the options.
4/Which of the following best describes the role of the last paragraph in relation to the passage as a whole?

A It summarizes the main position of the author. 
B It provides an exception to the author’s viewpoint. 
C It exemplifies one important goal of the author. 
D It highlights the difficulties of the author’s goals. 
E It provides a broader example of the author’s position

OA is C.

Last passage describes a large dam and why it should be removed?. Last paragraph gives more details about why glen canyon dam should be removed.
Clearly C is the only answer possible as from fist paragraph the theme of the article is that outdated dams must be removed. To justify the position the author gives one example.

Anandanwar · Answer

Hello,

For question 6: 
Choice A says that "fish ladders and other passage facilities have been generally ineffective in eastern dams".
For this we need to assume that fish ladders and other facilities have been already tries in the eastern dams.
Passage nowhere says that fish ladders have been tried in eastern dams. 
Could some one tell why are we assuming that?

Regards,
Ankit

guddo · Answer

6. According to the passage it is likely that:

The passage says eastern dams block anadromous fish runs. It then says western dams also block similar fish runs, and that fish ladders and passage facilities have been largely ineffective in reducing those negative effects.  The intended inference  is that such passage facilities are generally not very effective for dams that block  anadromous fish runs .

(A) fish ladders and other passage facilities have been generally ineffective in eastern dams.

This is correct. The passage directly says eastern dams block anadromous fish runs. Then it says similar passage facilities have been largely ineffective for western dams with the same type of fish-passage problem. So it is reasonable to infer that these facilities have generally not solved the problem for eastern dams either.

(B) most eastern dams will soon suffer catastrophic or partial failure.

This is too strong. The passage says most smaller eastern dams are at risk for catastrophic or partial failure. “At risk” does not mean they will soon fail.

(C) very few new dam projects will be approved in both the eastern and western U.S.

This is not supported. The passage discusses removing existing dams, not approving new dams.

(D) other large reservoirs formed by large western dams suffer from evaporation and seepage issues.

This is not supported. The passage says this about the Glen Canyon Dam reservoir, but it does not say the same is true of other large western reservoirs.

(E) the Glen Canyon dam blocks passage for many western anadromous fish species.

This is not supported. The passage discusses Glen Canyon Dam’s effects on Colorado River habitat and endangered fish species, not anadromous fish passage.

Answer: (A)

egmat · Answer

Hi Anandanwar,

You've spotted something real: the passage does only  say  fish ladders have been ineffective for  western  dams (Pacific salmon). So your instinct not to blindly extend that is a good one. The key is the exact word in the stem.

"According to the passage it is likely that"

This stem doesn't ask what the passage  proves  - it asks what is  probable  based on the passage. That's a lower bar than a hard, must-be-true inference. You don't need a line that says "ladders were tried in the East." You need the choice that the passage makes  most reasonable .

Now look at how the author keeps tying East and West together:

- " As in the eastern U.S. , the dams in the Pacific Northwest and California block passage for... fish..."
- " Likewise , fish ladders and other passage facilities have been largely ineffective..."

The author treats the fish-blocking problem, and the failure of passage facilities to fix it, as a  general shortcoming  across U.S. dams - not a western quirk. So  if  ladders were used on eastern dams, it's likely they'd be generally ineffective there too, just as in the West. That's the probable inference the stem is after.

Why the others are worse

Every other choice overreaches harder: B says failure "will soon" happen (passage only says "at risk"); D generalizes the  6%  evaporation figure, stated only for Glen Canyon; E says Glen Canyon blocks  western anadromous  fish, but that dam is on the Colorado with "endangered Colorado River" species, not Pacific salmon. Against those,  A  is the safest probable inference.

The habit to build:  when a stem says "likely," don't demand an exact stated sentence - pick the choice the passage's own parallels make most plausible.

Answer: A

Many of the dams in the eastern U.S. were originally built for water

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GMAT Reading Comprehension (RC) Questions

Many of the dams in the eastern U.S. were originally built for water

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