FORT WORTH, Texas — Some of the largest brewers in the U.S. are trying to reduce their water-to-beer ratio as drought and wildfire threaten the watersheds where they draw billions of gallons every year.

No independent group tracks beer-makers’ water usage, but MillerCoors and Anheuser-Busch both say they have made reductions. MillerCoors released a sustainability report Wednesday that shows it has cut its water use by 9.2 percent from 2012.

“Water is just critical to us,” Kim Marotta, the Chicago-based company’s sustainability chief, told The Associated Press. “Looking ahead, we needed to find a way to brew more beer but use less water.”

MillerCoors’ water-saving effort — focused in Texas, California and Colorado — involves using sensors to release just enough water for irrigation, planting native grass to reduce erosion and runoff and keeping a close eye on leaky machinery in its breweries.

Some craft beer-makers are also working to cut down on water usage while increasing market share.

The number of brewers in the U.S. has expanded to its highest level since the 1870s, mostly because of an explosion of craft breweries. Without the technology or scale of big brewers, craft brewers use on average as much as twice the amount of water for every barrel of beer.

Rahr & Sons Brewing Company, a craft brewer based in Fort Worth, produces about 22,000 barrels of beer per year. Co-owner Fritz Rahr said he does not know how much water he uses to produce each barrel, but says the company employs strategies to conserve water and energy.

“We use a heat exchanging system, which recaptures the heat energy from the brewing process, transferring it back to the new brew water for the next batch of beer,” Rahr said

MillerCoors’ massive Fort Worth brewery taps 770 million gallons a year from the Trinity River Basin, where tensions among private landowners, municipalities and other stakeholders are rising amid a persistent drought.

While MillerCoors isn’t restricted in its water use, residents in the Dallas-Fort Worth-area are. In some cities, residents can’t flush toilets from 10 a.m. to 6 p.m. each day and can water yards only on certain days, for example.

MillerCoors is giving out about $700,000 to landowners in the Trinity River Basin that use strategies that reduce erosion and runoff, such as restoring native plants and rotating cattle grazing, according to Trinity Waters, a nonprofit conservation group. That money is in addition to $7 million the U.S. Department of Agriculture is providing to finance improvements.

Elsewhere, MillerCoors is controlling water use by paying for and installing sensors on the lands of its hop and barley suppliers in Utah and Colorado to control the release of water depending on soil and weather conditions.