A federal judge ruled yesterday that Occidental Chemical Corp. is responsible for the costs, estimated at $250 million, of cleaning up Love Canal, the New York state community that came to symbolize the dangers of industrial pollution.

Judge John T. Curtin, of the U.S. District Court for the Western District of New York, concluded that "it is beyond dispute" that Occidental's disposal of tons of hazardous wastes in the 1940s and 1950s was "at least partially responsible" for subsequent leakage into the Love Canal community of Niagara Falls, N.Y.

While holding the company liable for cleanup costs incurred by the state and federal governments, Curtin said the exact amount would be set in further court action.

Occidental spokesman Sandra Kroeger called the decision "extraordinary" and added that while the company probably is "protected by insurance, we intend further to protect our rights by appeal."

Roger J. Marzulla, acting assistant attorney general for land and natural resources, hailed the decision as an "important victory" for the Superfund toxic waste cleanup program. The ruling, he said, helps to assure that "the parties initially responsible for creating this hazard must pay for cleaning it up."

The decision came in an eight-year court case brought against Occidental by the United States and the state of New York. A Justice Department spokesman said the court will be asked to order Occidental to pay full costs of cleanup, which are expected to reach $250 million to $300 million.

Love Canal, a 10-block area once populated by 900 families, dramatized the human costs of industrial pollution in the late 1970s when ground water containing cancer-causing chemicals seeped into the basements of homes. All but 86 families were evacuated, and the area was declared a federal environmental emergency.

The community was developed in the 1950s next to a landfill in which the former Hooker Chemical & Plastics Corp. dumped 21,000 tons of toxic waste from 1942 to 1953. Occidental Petroleum Corp. bought the firm in 1968 and renamed it in 1982.

Occidental contended in the case that the city of Niagara Falls, to which the property was deeded in 1953, was "solely responsible" for migration of the toxic wastes by disrupting the hydrology of the site with construction activities.

Curtin ruled, however, that the company cannot claim such a "third-party defense" because it brought the pollution to the site and is thus at least partly liable for the "release or threatened release of the chemicals from the Love Canal landfill during subsequent years."

A Justice Department spokesman said Curtin's rejection of the Occidental defense, while not binding on other courts, helps to build a case history against such arguments by other polluters.