SPOKANE — This year, officials believe target shooting or other firearm use sparked at least 21 wildfires in Utah and nearly a dozen in Idaho. Shooting is also believed to have caused fires in Arizona, Nevada and New Mexico.

Those concerns came as states grappled with ways to cut the risk of new fires in time for Independence Day, when many people fire their guns to celebrate.

In Utah, Republican Gov. Gary Herbert took the unusual step of authorizing the top state forest official to impose gun restrictions on public lands after a gunfire-sparked fire. The official is expected to do so within days.

Herbert said his decision doesn’t limit gun rights but is a common-sense response to dry conditions.

Advocates of gun rights are skeptical that the use of fire-arms could cause so many wildfires.

Clark Aposhian, chairman of the Utah Sports Shooting Council, said that perhaps 5 percent of the wildfires in the state have been caused by target shooters this year. “I don’t know how much of a problem it really is,” he said.

Utah officials believe steel-jacketed bullets are the most likely culprits, given that one shot that hits a rock and throws off sparks can ignite surrounding vegetation and quickly spread. Popular exploding targets are also blamed for causing wildfires.

The bullets were recently banned on state and federal lands in Utah. Officials are telling sportsmen to use lead bullets that don’t give off sparks when they hit rocks.

Many in the West are avid Second Amendment proponents, so most state lawmakers are hesitant to enact any restrictions for fear of a backlash.

“We’re not trying to pull away anyone’s right to bear arms. I want to emphasize that,” said Louinda Downs, a county commissioner in fire-prone Davis County, Utah. “We’re just saying target practice in winter. Target practice on the gun range.

“When your pleasure hobby is infringing or threatening someone else’s right to have property or life, shouldn’t we be able to somehow have some authority so we can restrict that?” she asked.

For weeks, state officials have said they are powerless to ban gun use because of Second Amendment rights, but Utah legislative leaders say they found an obscure state law that empowers the state forester to act in an emergency.

Among the recent fires, target shooters on June 21 ignited a blaze about 30 miles south of Salt Lake City that grew to about 9 square miles and forced the evacuation of about 2,300 people before it was contained.

Aposhian said his group will conduct tests to determine whether the steel-jacketed bullet theory is true.

If there are limits, “we want to make sure it is not knee-jerk legislation to ban guns or ammunition,” he said. “If it turns out the problem is with a few types of rounds, we will not be an apologist for them.”

There is no need for such tests, Utah state fire marshal Brent Halladay said. With steel bullets, “you might as well just go up there and strike a match,” he said.

Statistics on wildfires caused by firearms are incomplete because the federal government does not list “shooting” as a cause on its fire reports. But some officials write in “target” or “shoot” as a cause, said Jennifer Jones of the National Interagency Fire Center in Boise.

On land managed by the U.S. Forest Service only, the center found 17 such wildfires in 2010, 28 last year and 13 so far this year.

This year, the Bureau of Land Management said 11 of 31 wildfires it has battled in Idaho have been sparked by shooting activities.

In New Mexico, state forestry officials said a landowner was target shooting when one of his bullets hit a rock and sparked a small blaze. “This is a sign that we are very dry,” said state forestry spokesman Dan Ware. “We’re starting to see very unique ways of fire starting.”

Officials at Arizona’s Tonto National Forest had seven wildfires caused by firearms in 2010, 10 in 2011 and at least four so far this year. The potential for fire is so great that shooting for several years has been prohibited on BLM property in the Phoenix area.

In one case in the state, prosecutors said five friends at a campout and bachelor party set off an 18,000-acre fire on May 12 when one of them loaded an incendiary shell, which burns rapidly and causes fires, into a shotgun and pulled the trigger.

Associated Press writers Felicia Fonseca and Susan Montoya Bryan contributed to this report. Skoloff reported from Salt Lake City.