The situtation called out for a gesture of traditional American generosity toward the downtrodden and persecuted of the world. Just 90 miles from the shores of Florida, about 10,000 Cubans had crowded onto the grounds of the Peruvian Embassy in Havana to seek freedom from the communist government of Fidel Castro.

President Carter responded to their plight. The United States, he announced, would gladly welcome 3,500 of the refugees to its shores.

That is what he thought.

Exactly one week after Carter's announcement on April 21, 1980, the great Cuban boatlift got under way. Before it ended, the number of Cuban refugees to reach south Florida would not be 3,500 but 125,118.

Now, one year later, the aftermath of that chaotic event is apparent in Arkansas, Georgia and Florida, as well as Washington, where the Reagan administration is reviewing the entire question of refugee and immigration policy.

Administration officials say they already have a clear-cut policy should Castro ever again open his country to unlimited emigration.

"It is absolutely clear that this administration would not tolerate a massive influx of the type we witnessed in 1980," said Kenneth W. Starr, counselor to Attorney General William French Smith.

Putting that policy into effect, if necessary, and dealing with the aftermath of the 1980 experience, will be more difficult than simply declaring the administration's intentions to do so.

Last February, President Reagan ordered formation of an interagency task force headed by Smith that is to report its recommendations to him next week.

The task force is expected to recommend changes in existing laws and steps to deal with three distinct groups of Cubans who arrived on Florida shores during the 1980 boatlift.

By far the largest group, numbering more than 120,000 consists of Cubans who have been resettled with family members and friends or have found permanent homes through the efforts of private organizations such as the U.S. Catholic Conference. Although they entered the country illegally, they are here to stay, administration officials concede.

These Cubans reside in the United States under a temporary parole granted in the last weeks of the Carter administration and due to expire in mid-July. The Reagan task force is expected to recommend that this parole status be ended and that the Cubans be made eligible to apply for permanent status as resident aliens, the first step toward full citizenship.

"If they are going to stay here over the long term, there are very strong arguments that their status should be regularized," said one official familiar with the task force deliberations.

The second group of Cubans is still located at Fort Chaffee, Ark., in the last of what once were four resettlement camps.

These 2,593 Cubans are "clearly the more difficult cases," said Doris M. Meissner, acting deputy commissioner of the Immigration and Naturalization Service. For the most part, they are young men who have no family members in the United States, who lack job skills and who are given to what government officials term "antisocial" behavior patterns.

Gradually, the number of refugees left at Fort Chaffee is being whittled down as permanent homes are found for them. But when the resettlement process ends, about 1,000 of the Cubans are expected to have no place to go.

"We will have to make some permanent plan for them, but I can't tell you what it will be," Meissner said.

The third group, hard-core criminals released by Castro during the boatlift, has a home that some of its members may never leave. U.S. officials say they are detaining about 1,800 persons who entered the country during the boatlift, almost all of them at the federal penitentiary in Atlanta, an aging maximum-security prison.

Most of these prisoners have been given hearings to determine whether there are grounds to exclude them from entering the country and, in most cases, the answer has been yes.

One purpose of the hearings, officials said, is to guard against the remote but not impossible chance that Castro might agree to take the prisoners back.

In that case, U.S. officials said, the prisoners would already have been given their right to a hearing, and their quick transfer back to Cuba could not be delayed on legal grounds.

Castro, however, seems unlikely to readmit a group of people he was so willing to be rid of last year, making it likely that many of the Cuban criminals will remain indefinitely in U.S. prisons.

The prisoners' fate has been clouded by court decisions in which a federal judge in Kansas ordered the release from the Atlanta prison of a 48-year-old Cuban refugee who, the judge said, does not represent "any threat to public safety." (Pedro Rodriguez told officials he had been imprisoned in Cuba for stealing a suitcase at a bus stop.) The 10th U.S. Circuit Court of Appeals postponed the refugee's release until it decides on a government appeal.

U.S. District Court Judge Richard Rogers, in ruling that Rodriguez must be set free, found the government did not comply with his decision last Dec. 31 that illegal aliens could not be detained indefinitely because it violates their rights under international law and treaties and the U.N. charter.

But the appeals panel granted the stay after a U.S. attorney argued that it was needed to ensure "uniform, fair and efficient administration of the immigration laws."

Rodriguez' lawyer, Henri Watson, has filed a class action suit in Topeka, Kan., on behalf of Cubans now being held as prisoners.

At Fort Chaffee, in the Atlanta prison and throughout the Miami area, where the vast majority of Cuban refugees have resettled, controversy in the wake of the boatlift continues.

Reagan administration officials speak critically of Carter, accusing him of spending "mixed signals" that encouraged the Cuban flight until it was totally out of control.

Reagan officials say they would move quickly to halt a similar emigration effort, although it remains unclear whether any administration would have the resources and political willpower to stop thousands of Cuban-Americans from bringing their relatives to freedom in the United States.

"I think we are prepared," Meissner said. "But if something like this gets started, there is not much you can do. Preventing it from starting is the key."