Environmentalists and Southern Nevada’s water chief Pat Mulroy finally agree on at least one point.

A report by the Sonoran Institute, an Arizona-based nonprofit think tank, says that if the Las Vegas Valley’s population grows to capacity using the Bureau of Land Management acreage designated for development, even the most stringent water conservation measures won’t be enough to ensure that everyone has enough H2O.

Filling in the remaining 27,000 acres using today’s zoning and planning rules would allow about a half-million more people to call the valley home.

The one big problem: There’s not enough water for all of them.

The Sonoran Institute says that would remain true even if the valley adopted measures such as banning residential lawns and requiring low-flow fixtures indoors.

In other words, as Mulroy is fond of saying: We can’t conserve our way out of our water problem.

But Mulroy and the institute report, which was funded by the Progressive Leadership Alliance of Nevada and the Toiyabe chapter of the Sierra Club, part ways on what the answer is.

For more than two decades, Mulroy has pushed for a pipeline that would divert up to 170,000 acre-feet of water from eastern Nevada to support growth in Lincoln County and the Las Vegas Valley.