Editing Twelve leverage points (section)

=== 10. Structure of material stocks and flows (such as transport network, population age structures)===
A system's structure may have enormous effect on operations, but may be difficult or prohibitively expensive to change. Fluctuations, limitations, and bottlenecks may be easier to address. {{quote|For example, the inhabitants are worried about their lake getting polluted, as the industry releases chemical pollutants directly in the water without any previous treatment. The system might need the used water to be diverted to a [[Industrial wastewater treatment|wastewater treatment plant]], but this requires rebuilding the underground used water system (which could be quite expensive).}}