By the Stroke of a Pen

2013 brought a calamitous flood, certainly. For many areas it was a one-in-five-hundred-year event. For others it may have been bigger. Since then the creeks and canyons have been cleared of obstacles and re-engineered, presumably now better able to cope with an equivalent event. But on top of that the flood maps have been revised, and the building regulations, too. Based exactly on what? a layman would ask. For those living within the newly defined risk areas—some of the most beautiful properties in the county— their property values have plummeted and their options sometimes arbitrarily curtailed. For example, some obscure regulation states that existing houses in the [now] floodway can only be remodeled by 50% of the assessed value, measured in monetary terms, and then without increasing the footprint.  Where did that come from? And perhaps more importantly, why is the monetary value significant at all?