Back in 1957, the Army Corps of Engineers built a full-scale hydraulic replica of the San Francisco Bay, which has a complex watershed larger than the state of Rhode Island. The purpose was to study the tides and water changes of the massive area, hoping to figure out, say, how offshore sand dredging or a new thirsty housing development would affect the city.

On our way into San Francisco, we visited the Bay Model, a highly innovative idea in its time. Despite being largely replaced by advanced computer models, the original structure allowed engineers to tinker over the entire miniature replica (which is almost two full acres in size) before advising policymakers about how the region would react. Army Corps ranger