Study of Illegal Immigrants’ Fiscal Impact Called Flawed : Economy: Their number in San Diego County was exaggerated and their contributions minimized in report released by state, 2 UC experts on Mexican studies say.

A state report that claims illegal immigrants cost San Diego County $146 million annually in local government services is seriously flawed, two University of California experts on Mexican studies said Tuesday.

Leo Chavez, an anthropology professor at UC Irvine, charges that the report “exaggerated the number of undocumented immigrants in the county and underestimated their contributions.” The effect of those two miscalculations fatally flaws the entire study, said Chavez, who is studying the effects of undocumented immigrants on governmental agencies.

“I have some major problems with some of the major premises of the report,” Chavez said. “The whole idea that there are 200,000 undocumented immigrants in San Diego County flies in the face of common sense and academic sense and skews the entire report.”

The report, released earlier this month by the state auditor general’s office, was done too quickly and was too limited in scope to be taken seriously, said Wayne Cornelius, the director of UC San Diego’s U.S.-Mexican Studies Center.

The two San Diego State statistics professors who wrote the report defended their work, stating it shows that the federal government has burdened state and local governments with the influx of illegal immigrants. Their methodology and the degree of accuracy of their findings is similar to public opinion polls, said Louis M. Rea, who co-authored the study with colleague Richard A. Parker.

“We feel very comfortable with our results,” Rea said. “It is obviously very difficult, but we believe we got a representative sample of the immigrant population, particularly in San Diego County . . . and we got valid results.”

Rea and Parker’s 128-page study attempted to assess the impact of an estimated 200,000 immigrants on local services such as schools, health care, welfare and law enforcement throughout the county. Their findings revealed that annual costs to San Diego County totaled more than $206 million--including more than $105 million to the criminal justice system alone--leaving a net burden of $146 million after taxes are subtracted.

Rea said the 200,000 population figure represents 5% of the population of San Diego County, a figure he believes is reasonable, given a degree of accuracy of plus or minus 7%.

Cornelius, who has studied the effects of Mexican immigration for the past 12 years, also jumped on the 200,000 figure, calling it a “guesstimate” borrowed from various governmental agencies such as the Border Patrol and the INS rather than compiled during federal census counts. Using their figures as a basis can easily skew the report from the start, he said.