exemption allowing people to collect rainwater runoff from rooftops and certain other artificial impervious surfaces. So the distinction the case actually draws is between catching roof runoff and building reservoirs that trap streamflow. The second is what got him in trouble.
Why Water Rights Matter
Water rights are the piece most people skip, and they explain the whole mess. In much of the western United States, a system called prior appropriation governs who may use naturally flowing water. Existing rights get protected, and diverting or storing water without a permit can violate someone else’s claim.
I want to be precise here, because the internet muddles it. Rain falling from the sky does not automatically “belong” to downstream users. But once that precipitation becomes runoff or feeds into a regulated water source, water-rights law may affect who is allowed to divert or store it.
That is the line worth remembering. Catching
