The number of immigrant children entering the country illegally as unaccompanied minors is expected to rise in the current federal fiscal year to the second-highest level since 2008, according to an analysis of national border apprehension figures released Wednesday by a research organization in Washington, D.C.

About 39,000 unaccompanied minors are expected to cross the border and either surrender to or be apprehended by federal border agents in the fiscal year that started Oct. 1, 2014, and ends Sept. 30, according to projections by the Migration Policy Institute, which published the analysis.

The number is based on official apprehension figures issued by U.S. Customs and Border Protection for the first five months of this fiscal year.

Many of the children coming from El Salvador, Honduras and Guatemala likely will initially be resettled where there are established Central American communities, such as Long Island's Nassau and Suffolk counties, said Marc Rosenblum, author of the report.

"They are coming from similar communities and are headed to similar communities," said Rosenblum, deputy director of the institute's U.S. Immigration Policy Program. "The local impact is that whatever challenges school districts and local health care systems are under already, are likely to increase."

The nonpartisan institute, a nonprofit think tank, studies the movement of people across international borders and recommends related reforms.

The second wave of immigrants, as some are calling it, is expected even as children who arrived here in the last fiscal year, which ended Sept. 30, 2014, continue to move through a multistep immigration court process to decide whether they can stay or are to be deported.

More than 3,000 of those unaccompanied minors were resettled with relatives or sponsors on Long Island, making the region one of the top places in the nation to receive the children. Overall, about 68,000 minors were detained after crossing the Southern border illegally in the last fiscal year.

Some Long Island public school districts saw large enrollment increases from the surge of recent arrivals and felt pressured to give them needed classroom instruction and other educational services. At the same time, immigrant advocates and other organizations, including New York Communities for Change and the Long Island chapter of the New York Civil Liberties Union, mobilized to seek protection of the children's rights.

So far this fiscal year, 12,065 unaccompanied minors have been referred for resettlement by the U.S. Department of Homeland Security, said a spokesman for the U.S. Office of Refugee Resettlement, which shelters the children until they are released to relatives or other sponsors. About 620 of those had been resettled to Long Island and New York City as of February, with 178 in Suffolk and 113 in Nassau.

In addition to the influx of unaccompanied minors, children also continue to arrive in the United States with their mothers or other relatives -- a trend that is expected to continue. Those children are counted in federal statistics as being part of family units.

Victoria Campos, an immigration attorney with offices in Huntington Station, Bay Shore and Riverhead, said she currently represents children who came from 2013 to 2014. While she has about 25 newcomers who are clients, she said she has seen a decline recently, noting there is a monthslong lag until immigration attorneys notice a spike in cases.

"I tend to agree that there is going to be a second wave," said Campos, adding that "a lot of the minors that have come are here because something traumatic has happened in their lives," and the conditions in their home countries haven't improved in the past year.

They have been fleeing to this country because of a combination of factors, including high crime, gang violence and severe poverty in El Salvador, Honduras and Guatemala, known as the "Northern Triangle" of Central America. Those three countries have cities with some of the highest murder rates in the world.

Long Island has been a magnet for immigrants from the region since the late 1970s, when Salvadorans started coming here fleeing war. That migration continued, and many of the children who are recent arrivals could seek to reunite with relatives here.

The effect of the recent surges in border crossings has been felt more acutely in the schools in communities where there were established immigrant populations.

The Hempstead school district, in particular, became the focus of investigations by the state attorney general's office and the state Education Department after advocates complained that the newly arrived immigrant children were turned away from school for weeks last fall.

The district scrambled to open a transitional school for those children in October. Last month, in a settlement with Attorney General Eric T. Schneiderman's office, district officials agreed to have enrollment procedures monitored by the state until 2018 as they try to comply with the legal mandate to educate all students ages 5 to 21.

There are larger concerns for the region and its schools, as the influx of students is expected to put a strain on districts operating under state-imposed property tax caps. Efforts to seek special aid from the state and from Congress for affected districts stalled over the last several months.

Roger Tilles, Long Island's member of the state Board of Regents, which sets education policy, said this week he is "very concerned about Hempstead and some of these high-need districts" that receive the bulk of the immigrant children.

"It's a bind not just for the schools, but it's a bind for the kids that are already in the schools," Tilles said, "because with a limit to what a school can raise on property tax caps and increased students . . . there is no place to go, except take away from existing programs."

He added that he wants to see all the kids receive a proper education.

Norman Wagner, school board president in the Central Islip district, said "a large number of undocumented immigrant minors" were resettled in the area and it "far exceeded our student enrollment projections" for the current school year.

"We will educate every child," Wagner said in a written statement. "However, unannounced placements of students by the federal government must be funded by the agency which placed these students."

Other districts on the Island that saw enrollment increases because of the recent arrivals include Brentwood, Freeport, Glen Cove, Hampton Bays, Huntington and Westbury.

Groups that want stricter immigration enforcement blame the federal government for inaction as taxpayers bear the costs of immigration that occurs illegally. They want anti-trafficking laws to be changed so that immigrant children can be turned back at the border.

"People [in Central America] are getting information from those who have come to the United States, who say 'You get here, they put you through a procedure and release you,' " said Ira Mehlman of the Federation for American Immigration Reform, a group based in the nation's capital that lobbies for reduced immigration levels.

"Unless the federal government dramatically changes its policies on how they deal with the new arrivals, we can expect to see almost the same number of new arrivals as we did last year, because there's no reason for them to stay" in Central America, said Jessica Vaughan, policy studies director of the Center for Immigration Studies, another Washington-based group that seeks strict enforcement.

The institute's analysis, however, calls the federal government's efforts "a success" because the flow of immigrants is decreasing. It credited, in part, a "multifaceted regional policy response" in which the United States partnered with Mexico and Central American nations that "greatly reduced" illegal crossings as the numbers reached crisis levels last year.

Marsha Catron, a spokeswoman for the U.S. Department of Homeland Security, which oversees several of the immigration agencies, said the federal government "devoted unprecedented manpower and resources to securing our southern border" and continues "to review and update our plans and procedures to ensure we are as prepared as possible for any potential scenario."

The department, Catron said, sent more patrol agents to secure the border, particularly in South Texas. The agency also built more detention space and launched a campaign in Central America to highlight "the dangers of the journey" and tell potential migrants they would not get a free pass here, she said.

In addition, the Obama administration has stepped up "in-country" refugee processing so that immigrants here legally can petition to have their children come to the United States rather than arrange to have them smuggled into the country.

But advocacy groups said little has been done to help communities that have received the children. A recent $14 million federal grant for education costs would be a drop in the bucket, they said, when divided among affected schools across many states. With the arrival of more unaccompanied minors, nonprofits also may run out of grant funds to provide legal representation and support services.

"A broader conversation" should occur about how the federal government helps the states and local governments with the costs, said Margie McHugh, director of the Migration Policy Institute's National Center on Immigrant Integration Policy, which is a resource for localities working to help immigrants succeed.

The migration of minors "won't go away, but it probably won't be the crisis that we had last summer," McHugh said. She expressed the hope that "cooler heads will prevail" in setting policy and getting financial aid from Washington.