Understanding Dams and Their Impact

What are some of the benefits historically associated with dam construction?

• Reducing air pollution

• Powering machinery and controlling floods

• Increasing fish populations

• Decreasing water levels

What environmental issues are caused by older, obsolete dams?

• They increase water flow speed

• They improve water quality

• They cause algae blooms and block fish migration

• They reduce greenhouse gas emissions

How did the removal of dams on the Klamath River benefit the ecosystem?

• It caused more flooding

• It improved salmon migration and reduced algae

• It increased algae blooms

• It decreased the number of salmon

What was a significant outcome of the Elwha River Dam removal?

• A rise in greenhouse gas emissions

• An increase in Chinook salmon returning

• A decrease in bird populations

• A reduction in river sediment

What role did Indigenous communities play in the Klamath River dam removal?

• They opposed the removal

• They led the restoration process

• They were not involved

• They built new dams

What was a key reason for removing the dams on the Sélune River?

• To increase phosphorus levels

• To improve water quality and reduce algae blooms

• To trap more sediment

• To build new hydroelectric plants

What is a counterintuitive effect of clearer water after dam removal?

• It reduces sediment transport and erodes riverbanks

• It increases fish populations

• It decreases algae blooms

• It improves water quality

What was a major environmental issue caused by the Milltown Dam?

• It reduced greenhouse gas emissions

• It improved water quality

• It trapped toxic sediment containing arsenic

• It increased fish populations

What was the sequence of actions taken to remove the Milltown Dam?

• Divert river, remove sediment, dismantle dam

• Dismantle dam, divert river, remove sediment

• Dismantle dam, remove sediment, divert river

• Remove sediment, divert river, dismantle dam

What is a broader benefit of dam removal, as seen in the Milltown case?

• It restores ecosystems and creates recreational spaces

• It increases water pollution

• It creates new industrial sites

• It reduces biodiversity