County officials are challenging what they say is a serious census undercount of the Utah Navajo Reservation population.

San Juan County commissioners notified the district office of the U.S. Census Bureau in a letter Sept. 10 that most of the figures in the preliminary housing unit and population counts will be protested by the county.Commissioners will also challenge the count in person this week during a two-day trip to meet with various directors of federal programs, said Mark Maryboy.

"We're going to tell them the count was inaccurate," he said. "I'm going to insist that they do a recount of everybody in the Utah portion of the reservation."

Ron Ritschard, regional census center media specialist, said Friday that San Juan and Weber are the only counties in Utah to protest census figures to date. He said 18 formal challenges had been filed with the Denver center in a count earlier in the week.

Ritschard emphasized that the numbers are preliminary and are constantly being updated as field follow-up and special counts come in.

"The information we have may be even more recent than the preliminary numbers that were sent out, in some cases," he said.

According to the post-census local review received by San Juan commissioners the last week of August, the total population in the county as of April 1, 1990 was 12,360. That compares to 12,253 in the 1980 count, Ritschard said.

"Compared to 1980, it is absolutely ridiculous," said Commission Chairman Ty Lewis. "We're going to challenge everything."

In the protest letter, the commission said the portion of the county within the Utah Navajo Reservation in particular appears to have been undercounted "by rather large numbers."

It said county officials and Navajo advocate groups have questioned whether the census was properly administered throughout the Navajo reservation, including Arizona and New Mexico.

The preliminary count for 1990 shows 136,698 Navajo Nation residents. The 17-million acre reservation includes the Utah Strip in San Juan County.

Maryboy said the census accounted for 4,778 Native Americans in San Juan, which includes a portion of the Ute Reservation. But he thinks the local Native American population is closer to 10,000.

"We've been registering Navajos. We've got more registered to vote than that," he said.

Commissioners compared numbers in the preliminary count with with the number of registered voters through 1988, census figures from 1980, local counts, school enrollment, building permits that have been issued and other information.

Ritschard said the Navajo tribal government did a great job promoting the census through media campaigns, but enumerators face several challenges on the reservation that are less of a problem in other communities.

"Number one, the inaccessibility," he said. "And there's always that resentment or fear among the population, of big government - so there's a hesitancy to be counted."

"That's an acknowledged problem, working with any minority group - fear, misunderstanding or distrust of big government," Ritschard said.