MANKATO — A state law limiting access to cold medicines has dramatically reduced methamphetamine arrests in the area, but drug investigators say they’re also seeing a growing market for another well-known illegal drug.

Arrests continue to be made in a string of cocaine stings last fall by the Minnesota River Valley Drug Task Force. Tyrell Langston, 39, of Mankato is the latest person to be charged in Blue Earth County District Court for allegedly selling cocaine to police informants or task force investigators.

He’s accused of selling just over a half ounce of the drug to an informant for $450 on Nov. 9 while in the parking lot of the downtown Hy-Vee store. Prosecutors requested a high bail because Langston is facing a minimum of 86 months in prison if convicted. He’s on probation for a first-degree drug conviction in Ramsey County.

It’s one of several recent arrests for alleged cocaine sales last fall, but the arrests are not what would be considered a sweep, said North Mankato Police Chief Mike Pulis, a member of the drug task force’s board of directors. He said the team of investigators from sheriff’s and police departments in Blue Earth, Nicollet, Watonwan and Martin counties are making arrests for investigations that are no longer expanding.

The arrests suggest there is more cocaine available in the area than there was when methamphetamine labs seemed to be popping up everywhere, Pulis said. Many of those labs depended on large quantities of over-the-counter pseudoephedrine pills to make meth, which could be “cooked” in makeshift labs investigators were finding in homes in towns and rural areas, parks and even moving vehicles.

There were four methamphetamine labs found by the task force in 2005, and the number grew to six in 2006. Only one lab was seized last year. Pulis credits a state law, enacted in 2005, that limited access to cold medicines and restricted the number of pseudoephedrine pills people could buy at one time.

The drop in the number of meth labs that have been turning up since then is the good news, Pulis said. The bad news is illegal drug users could be turning to cocaine to fill the gap.

In addition, investigators don’t believe the drop in methamphetamine use will hold. They’ve been told by colleagues in other states where similar cold medicine laws have been passed that it will only be a matter of time before the demand for meth is filled by dealers importing the drug from Mexico.

“You can’t easily buy the active ingredients of meth anymore, that’s cut down on labs,” Pulis said. “But it’s like any competitive business. What we have been told is, when this happens, someone will be ready to step up and fill that market.

“In the meantime, more people are going from meth to coke and crack. We expect we will see a replacement of meth in the form of the manufactured product coming up from Mexico.”

Many of the fall cocaine stings took place in public parking lots or other common areas, such as a downtown alley. That isn’t something that is controlled by task force investigators, Pulis said.

Dealers usually set the meeting places, he said. Often they have informants and investigators meet them at restaurants or businesses where they happen to be going when they want to do the deal.

There are two reasons dealers rarely want to sell drugs from their residences, Pulis said. One is residents have learned to report suspicious activity in their neighborhoods, such as repeated short visits to a certain house or apartment. The other reason is people selling drugs don’t want other dealers to steal their stash and cash.

Methamphetamine is still being found on suspects by deputies on routine patrol, said Capt. Rich Murry of the Blue Earth County Sheriff’s Department. And even if methamphetamine levels return to what they were in the area because drug traffickers are importing it, it’s still a good thing to have the number of “cooking” labs reduced, Murry said.

Those labs create chemical hazards that can be poisonous and explosive.

“The labs, themselves, are so dangerous,” he said. “Not only to the people cooking, but also to the emergency response people who have to deal with the aftereffects.”