For the first time in three years, arrests of illegal aliens along the porous United States-Mexican border are down dramatically. In some sectors, the numbers have dropped well over 25 percent. Nevertheless, federal officials say it is too early to tell if the dip is part of a long-term trend, or if the new immigration law is a key factor behind the falloff.
``Perhaps it is the lull before the storm,'' says Wayne Kirkpatrick, a supervisory agent with the US Border Patrol here, the nation's busiest crossing. ``The agents are still busy,'' he adds.
Two other discernible trends are emerging three months after the sweeping immigration measure was signed into law:
Arrests of aliens from countries other than Mexico, which in recent years had been up, are dropping the most dramatically. This is of more than idle interest to the US Immigration and Naturalization Service (INS). The US foots the bill to send many of the non-Mexican illegals home. A drop in these arrests could mean a big saving in ``deportation'' costs.
A growing number of aliens in this country who are not eligible for legal status under the new law have been migrating to Canada.
Between Jan. 1 and Feb. 15 some 6,120 aliens, taking advantage of that country's relatively liberal policy, applied for refugee status in Canada. Many of the applicants were Guatemalans and Salvadoreans now believed to be living in the US.
But on Feb. 20, the Canadian government issued strict new rules that ended its program of automatic addmission to foreigners claiming to be political refugees.
January marked the third straight month that arrests along the 1,900-mile US-Mexican border dropped. Overall, detentions in January were down 26 percent over the same period a year ago. But they dipped a modest 12 percent in the San Diego area.
``They're just not coming like they have been in recent years,'' says David Durant, an agent with the border patrol in El Paso, Texas.
Federal authorities cite several reasons for the decline. One has been unusually cold weather and high-water conditions along the Rio Grande, which has contributed to a reduction in parts of Texas.
Another theory is that many illegal aliens who traditionally return home for the holidays may have stayed in the US this year to avoid interrupting their continuous residence status. Under the new immigration law, signed by President Reagan Nov. 6, aliens applying for legal status under ``amnesty'' provisions must demonstrate an unbroken residency in the US.
Federal officials speculate that the central element of the measure - legal sanctions against employers who hire illegal aliens - may be having some effect. Although the sanctions will not be enforced until June 1, employers were required in November to start examining the documents of all people hired to establish their identity and work authorization.
``We think there is no question that word has gotten out that employers are asking for documents,'' says Duke Austin with the INS in Washington. But ``the mere signing of the document will not deter illegal immigration. It will depend on how we enforce it and what employers do,'' he adds.
The downturn in arrests does not necessarily mean there has been a precipitous drop in the number of illegals entering the US. Although the arrest rate is usually a crude indicator of illegal immigration, some INS officials complain that enforcement has been down in certain areas because of a new requirement that agents obtain a warrant before searching for aliens on farms and ranches.
Moreover, despite the drop-off, this past month was still the second-busiest January on record for many border stations. In recent days, some posts have begun seeing arrests rise again. The real test, agents say, will come this spring and summer, when the biggest surge in illegal immigration usually occurs and the sanctions go into effect.
Heartening to some INS officials has been the sharp decline in non-Mexican arrests, though officials are uncertain why it is occurring. In recent years, citizens from Central America, as well as from as far away as India and China, have been coming across the southern border in increasing numbers.
But in January, arrests of non-Mexicans plummeted 48 percent in San Diego and 54 percent in El Paso. This has led to a drop in what the US spends on airline tickets to send aliens home.
In the last quarter of 1986 the two deportation centers in southern California were putting out some $30,000 a week for transportation. That dropped to $16,000 a week in January.