After weeks of record-breaking rainfall have seen freeways flood, hillsides collapse and the dry concrete gutter of the Los Angeles River transform into a raging torrent, you may have assumed that California’s water-shortage woes were beginning to ease. With many areas receiving their usual annual rainfall in just three weeks, surely the multiyear megadrought is finally abating. Sadly, no. Decades of building concrete gutters – driven by the mindset that stormwater is a threat to be banished, not an asset to be stored – have meant that the vast majority of that rain was simply flushed out into the ocean. Of the billions of gallons that have fallen on the LA area, only a tiny fraction were absorbed into the ground.