For communities across the wildfire-weary West, Las Vegas has become a warning sign, showcasing the damage that can be inflicted on delicate water ecosystems by megafires and other climate-charged disasters, and putting another obstacle in the way of recovery. Protecting Las Vegas’s drinking water will be difficult and expensive — with federal, state and local resources all being drawn on to shore up the system. The cost further highlights the demands that climate change is placing on communities across the country, as they deal with an onslaught of more intense and frequent droughts, storms, wildfires and other disasters.