For instance, city families use far less water per capita than rural and suburban families, and they produce fewer "capitas".
https://www.sfgate.com/bayarea/article/S-F-residents-praised...
And compare "water used in California to produce almonds exported to other countries" versus "water used for all SF/LA homes and businesses" below:
https://www.motherjones.com/wp-content/uploads/LA-vs-Exports...
Similarly, when you take people from elsewhere in the country and move them to places like San Francisco, their consumption of fuel and electricity go down, as does their production of garbage.