HELENA – A proposed expansion of the region in southwestern Montana known to harbor infected elk could affect more agricultural producers, including raw-milk producers.

On Tuesday, the Montana Board of Livestock voted unanimously to approve the expansion of Montana's Designated Surveillance Area for brucellosis to include 365 square miles in Gallatin County between Norris and Three Forks.

State Veterinarian Martin Zaluski said the expansion was necessary because 10 of 40 elk sampled in the Blackford area near the lower Madison River had tested positive for brucellosis.

Similar sampling in the Tobacco Root Mountains to the west yielded only negative results.

Roads make up most of the boundaries of the new area. Churchill Road is the east boundary down to Norris Road and the west boundary out of Three Forks follows the Madison River down to U.S. Highway 287 to Ennis.

The surveillance area already existed south of Norris Road.

Zaluski said the expanded area would require around 50 livestock producers to test around 12,000 cattle at an added cost of $30,000 annually.

Two dairies in the area already have to be tested using a separate test so they wouldn't have to do additional tests.

Montana Farm Bureau Federation spokesman John Youngberg expressed concern over raw milk sales, which are a growing industry in the Gallatin Valley. The milk of infected cows can contain brucellosis bacteria.

Zaluski said the threat of brucellosis was an additional concern since raw milk isn't pasteurized, but he didn't know how producers in the area might be affected. He said it might be up to the Legislature.

The new boundaries will now go out to public comment.