The state of California has over 1,000 dams, many built from the 1930s to the 1970s to reduce flooding and to create hydroelectric power. A dramatic decrease in salmon and trout populations were noted in the dammed rivers. The state has recently begun to research dam removal to restore rivers to their original flow. Which of the following is a possible benefit of removing some dams?
A. Restoration of migrating fish habitats and related food web species.
B. Increased hydroelectric power output from remaining California dams.
C. Better long-term drought prevention from reservoirs.
D. A decrease in flooding events downstream from where the dam is removed.

A. Restoration of migrating fish habitats and related food web species.

Explanation:

The removal of dam is likely to increase the incidences of flood because of overflow of river water, it will also decrease the output of electricity generation in California. The dam can keep the river water in a circulation hence can also prevent it to dry. Thus without dam the river water is expected to dry and condition of drought may result in California.

The removal of dam will help in restoring the biodiversity of the free flowing river. The marine animals can migrate in river water which has been restricted from flowing. The salmon and tout populations may get restored in terms of numbers. Also, this initiative will restore the food web as many marine species are dependent on each other for food needs.  

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