The Minnesota Department of Natural Resources has targeted a troubled Fillmore County deer farm in a case highlighting tension between the DNR and Board of Animal Health as the DNR tries to halt the state’s biggest-ever outbreak of chronic wasting disease (CWD).

In an exchange of letters earlier this month, DNR Commissioner Tom Landwehr requested that the Board of Animal Health immediately suspend the deer farming license of a Spring Valley man and quarantine the farmer’s small, captive deer herd. The farm, which is said by the DNR to have unintelligible records and an unresolved escape of penned whitetails, is located near the wooded hills where 10 CWD-infected wild deer were discovered starting last fall.

State veterinarian Beth Thompson, who heads the Board of Animal Health, responded to Landwehr’s Aug. 10 letter one day later. She called certain DNR actions and observations into question and asked Landwehr to refrain from blaming deer farmers for spreading CWD to wild game.

The Star Tribune obtained the letters in a public records request.

“Assumptions about CWD in any population, farmed or wild, is only damaging to both agencies and is misleading the citizens of Minnesota,’’ Thompson wrote.

In an interview Friday, Thompson said her agency is still deciding how to deal with the farm. And while DNR officials fret over the possibility that farmed deer are spreading CWD to wild deer, Thompson wonders if farmed deer in Fillmore County’s endemic zone are contracting CWD from the wild population.

Asked Friday if the animal health board’s relationship with the DNR over CWD control is strained, Thompson said: “Both agencies are very passionate about what we do. … Does that come across as tension? It probably does.’’

Landwehr said Friday that the Spring Valley farm “is a really good example of a really bad operation.’’ If Minnesota really cares about the health of its invaluable wild deer population, he said, the farmer’s license should be revoked.

“We can’t do the things I wish we could so we rely on the Board of Animal Health to help us in the strongest way possible,’’ Landwehr said. Infected captive deer “have been vectors of CWD in the past,’’ he said.

The commissioner said tension between the DNR and Board of Animal Health stems from different clientele. The board serves deer farmers, and the DNR serves “all of Minnesota,’’ Landwehr said. A badly managed farm shouldn’t be allowed to jeopardize the health of a wild herd that “dwarfs the value of all the [deer] farms combined,’’ he said.

Landwehr said he is glad the Board of Animal Health’s oversight practices will soon by evaluated by the Office of the Legislative Auditor.

Judy Randall, deputy legislative auditor, said one focus of the audit will be the relationship between the DNR and Board of Animal Health. The agencies have split powers assigned by the Legislature. Legislative Auditor Jim Nobles said the evaluation is likely to start in mid-October and should finish by early March.

Lou Cornicelli, wildlife research manager for Minnesota, said the DNR’s investigation of the Spring Valley deer farm hasn’t found a link to the CWD outbreak in Fillmore County’s wild deer. But the disease has been discovered previously on deer farms in Minnesota, most recently in herds in Meeker and Crow Wing counties, where the DNR is now on the lookout for new outbreaks.

Michelle Carstensen, DNR wildlife health program supervisor, said she and Cornicelli turned to the Board of Animal Health early in last year’s CWD outbreak, asking if any deer farms in Fillmore County were problematic.

“The answer was ‘Nope, they’re all great,’ ” Carstensen said.

But when CWD investigators heard rumors about escaped captive deer and observed two dead deer with markings suggesting they were once ear-tagged as livestock, the DNR asked to review for itself the board’s records of deer farms in Fillmore County.

“Of the farms we looked at, we’ve seen a lot of issues with compliance,’’ Carstensen said.

Once the DNR sought to review the board’s data, she said, the board downgraded the status of at least two farms.

Dr. Linda Glaser, a senior veterinarian at the Board of Health, has been reviewing deer farm records at the agency since June, when she began oversight responsibilities for deer farms. She replaced Dr. Paul Anderson, who retired.

Glaser declined to comment on the Spring Valley deer farm under investigation by the DNR.

According to Landwehr’s letter, DNR officers found “irregularities’’ in records kept by the Spring Valley farm, prompting an inspection July 20. Inspectors discovered that a June windstorm had damaged a fence, allowing all deer to escape. Farms are required to promptly report escapes, but the farmer in Spring Valley waited three weeks, the letter said. The farmer did not try to recapture the animals, as required, the letter said.

“Record-keeping is so poor that DNR officers believe that it is impossible for [the farmer] to determine the number of deer that are still at large,’’ Landwehr wrote.

The letter noted the farmer’s failure to mark his herd with ear tags, as required by law. In addition, the farmer never heeded an order to repair his fence, the letter said.

Landwehr wrote that DNR conservation officers were compelled to shoot deer that they believed had escaped from the farm to “protect the wild deer population from potential exposure to CWD or other diseases.’’ His letter said the farmer interfered with those efforts.

But in her rejoinder, Thompson said the farm’s enclosure was fixed and that the farmer told the board that DNR officers scattered a group of escaped deer when the deer were in position to be tranquilized. She also cast doubt on a report by DNR officers that some deer inside the Spring Valley farm may have been wild deer because they didn’t act like farm-raised deer.

Asked why the Board of Animal Health and DNR couldn’t agree on whether the farmer’s fence was repaired, Thompson said, “I can’t speak to where Commissioner Landwehr got his information.’’

Thompson noted in her letter to Landwehr that the farmer received a $250 fine and that the board dropped his status to stop him from moving deer off the farm.

Lt. Col. Rodmen Smith, who heads the DNR’s enforcement division, said the DNR’s investigation of the Spring Valley farm is “moving forward.’’