Question

1 mark for review hoover dam is the largest dam in the united states, built on the colorado river to supply hydroelectric power and flood control. which of the following best describes a downstream environmental effect of hoover dam on the colorado river watershed? a the supply of inexpensive electricity led to population growth and industrial development in cities such as phoenix and los angeles. b the lake mead recreation area, formed by the reservoir behind hoover dam, is a popular tourist attraction for fishing, swimming, and boating. c the drainage basin of the colorado river includes 246,000 square miles and serves as a source of drinking water for over 40 million people. d the damming of the colorado river led to a change in stream flow, preventing river water and sediments from reaching the delta area.

Explanation:

• Option A: Population growth and industrial development are social - economic impacts, not environmental effects on the river watershed.
• Option B: The recreation area is an impact related to human leisure activities, not a downstream environmental effect on the river's natural state.
• Option C: The fact that the river serves as a drinking - water source is a general characteristic of the river, not a downstream environmental effect caused by the dam.
• Option D: Damming changing stream flow and preventing sediments from reaching the delta is an environmental effect on the downstream part of the river watershed.

Answer:

D. The damming of the Colorado River led to a change in stream flow, preventing river water and sediments from reaching the delta area.