There's something fishy going on in some of those little shacks that dot the state's lakes in the winter.

Authorities say ice-fishing houses are being used as bases for illegal methamphetamine manufacturing, a trend they describe as logical in a troubling sort of way.

"It's been going on for a couple of years now," Attorney General Wayne Stenehjem said. "We're concerned about it because it's a double hazard - as soon as (authorities) come up on one of the ice houses, evidence is dumped down the hole and those toxic chemicals go into the lake."

McLean County Sheriff Don Charging arrested several people last year who had set up meth labs in fish houses at Lake Audubon.

Increased patrols and public awareness have helped curb the shack-labs at the lake, though officials believe the activity is continuing because ice-fishing houses are nearly ideal for meth labs.

"Nobody really ever has patrolled on the lakes in the past," Charging said. "(Fish houses) have good visibility and it's easy for the evidence to disappear down in the holes … unfortunately, it makes logical sense."

Audubon Refuge Manager Gary Williams said the problem is "not a monster issue yet," but he acknowledged that the fish houses are "a perfect decoy for cooking meth."

Tim Rader, who builds fish houses in Mandan for Zachmeier Manufacturing, said he worries the clandestine meth labs on ice could turn into mini toxic waste sites.

"It's kind of scary - it's crazy," he said.

Rader said his company's fish houses come with anti-theft features such as locking doors and retractable wheels, so they can't be driven away.

"Nothing will really stop a vandal or a burglar," Rader said. "If they want to get in, they'll get in."

Meth makers use such ingredients as anhydrous ammonia, solvents, lithium batteries, hydrogen peroxide and ephedrine or pseudoephedrine tablets. "Dumping that waste down a hole can't be good," Rader said.

Meth labs first started showing up in North Dakota in rented farmhouses, then in abandoned farmhouses, Charging said. Those farmsteads have been targeted by authorities, forcing criminals to find other locations to make meth.

"As soon as one thing is addressed, they move on to something else," Charging said. "They always seem to be one step ahead."

Authorities dismantled 260 meth labs in 2004, down from 297 in 2003, data from the state attorney general's office shows. About one-fourth of the labs were in northwestern North Dakota's Williams County, which had 67 meth lab busts last year, compared to 70 in 2003.

Williams County deputies have found evidence that fish houses have been used as meth labs on Lake Sakakawea, but no arrests have been made, said Sheriff's Capt. Bob Stancel.

"We know meth has been smoked in them and we've found some paraphernalia around them," he said. "We know there has been some cooking going on in them.

"They are well ventilated, somewhat remote and it's kind of difficult to sneak up on a fish house," Stancel said.

Mel Samuelson, who owns a cafe, lounge and bait shop at Lake Audubon, said he has noticed "a lot of uniforms out here snooping around" on the lake, which is home to about 300 fish houses. The increased patrols are justified, he believes.

"I know some of those people will try anything," Samuelson said. "You can't leave anything unlocked because there's a lot of goofy guys out there."

Samuelson said the fish houses are part of a little community on the lake, where neighbors often watch out for one another and report suspicious activity.

"I think 70 percent of them would turn (a drug maker) in, and 30 percent will look the other way," he said.

Dean Hildebrand, director of the state Game and Fish Department, said hunters and anglers have helped report meth labs in the past.

"Be on the alert, and if you see something weird, you might want to give a sheriff a call," he said. "People are going to do foolish things."