When the supply of a good is diminished, its cost goes up. That is an ironclad rule of economics. But how that cost is covered can vary. With water in the West, the rising cost is most likely to be paid in pain, effort and attention.

That is if residents of Colorado and its neighboring states are smart. If we ignore the situation or try to kick it down the road, we will be in serious trouble.

One hundred years ago, seven Western states came to an agreement called the Colorado River Compact on how to allocate the area’s water. It divided those states into the Upper Basin – Colorado, New Mexico, Utah and Wyoming – and the Lower Basin – Nevada, Arizona and California.

But the West has changed a lot since 1922. Since the compact, California’s population has grown vastly more than Colorado’s.

With that, most of the water originates in the Upper Basin. And most of the people – also called voters – live in the Lower Basin.

This came to the fore this week when water managers from the Upper Basin sent a letter to the Bureau of Reclamation, advancing their ideas to address the plight of the Colorado River system. That was in response to the Bureau of Reclamation’s June demand that the seven states produce a plan by August to decrease overall use of the river’s water by 2 million to 4 million acre-feet by the end of 2023. The Bureau of Reclamation is particularly concerned about the disastrously low water levels in lakes Powell and Mead.

The Upper Basin’s letter offers increased releases of water from some of its reservoirs, enhanced conservation research and improved water management, but no mandatory cuts. What jumped out, however, was its assertion that the Lower Basin must do more.

That only makes sense. For all its gravity, the facts of the issue are simple: There are too many people in a part of the world that is largely dry and prone to drought.

Jacques Cousteau, the late oceanographer and filmmaker, used to refer to Earth as “the water planet.” And he was right. Seen from space, it is obvious that our home world is largely covered with water. It is miles deep in places.

But people do not live in the Marianas Trench. Nor do they drink seawater. They do, however, have a propensity to build homes in semi-arid places like Southern California and even in true deserts such as Phoenix or Las Vegas.

So, while the Upper Basin’s letter was right – the Lower Basin states need to do more. But we in the Upper Basin also need to proceed with care. If we ignore the issue, the huge and growing populations of the Lower Basin states will take more of our water. But conflict could be equally disastrous. In both money and votes, the Upper Basin is simply outgunned.

We need to pay attention.