Key Concepts
• Obtaining water and power—no matter the source—has environmental,
economic, and social impacts. (From NGSS ESS3.C)
• The urban water cycle is the process by which cities get and use water
and treat wastewater. In San Francisco, this cycle involves moving water
from the source in the Sierra Nevada mountain range, treating the water
for safe consumption, distributing it to businesses and households,
collecting and treating the wastewater, and then releasing the water back
into the environment for the cycle to begin again. Each step of this cycle
can impact the environment.
• Human communities create wastewater from their homes and surface
streets, which may carry diseases, toxins, and other contaminants that
must be treated and removed from the water before it is released into
the environment.
• Burning fossil fuels is impacting the global climate, but even renewable
energy resources have environmental consequences.
• Typically, as human populations and per capita consumption of natural
resources increase, so do their impacts on Earth. (From NGSS ESS3.C)
BIG IDEAS
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Grades 6–8
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SAN FRANCISCO PUBLIC UTILITIES COMMISSION
57