Arizona water managers are being accused of finding a way to gain the system as climate change takes hold and there may not be enough water to fill both Lake Powell and Lake Mead.

Under a formula set by the state and the U.S. Interior Department, Lake Powell will send 9 million acre-feet to Lake Mead this year to prevent shortage, rather than the 8.23 million acre-feet it would send under normal river conditions. Each acre-foot is about 326,000 gallons and is enough to serve about two households for a year.

Conserving enough to prevent a shortage but not so much as to slow the flow from Lake Powell represents a “sweet spot,” CAP argued, in language that has now alarmed upstream water officials…

CAP’s “manipulation of demands in order to take advantage of the supposed ‘sweet spot’ in Lake Powell water releases undermines (regional conservation), and is unacceptable,” Denver Water CEO James Lochhead wrote.