Taxing the property owned by Washington's colleges and universities, "would cause great and immediate harm to the institutions and to the community," the president of George Washington University warned yesterday.

Dr. Lloyd Elliott said the universities, which are attended by about 80,000 students, provide jobs for 30,000 persons and insure medical care for thousands more, should not be forced to contribute still more to the community through taxes.

Elliott defended the tax exempt status of colleges and universities in a speech to members of the District of Columbia Bankers Association at their annual convention at The Homestead resort.

The nine colleges and universities in the District are a billion-dollar-a-year boost for the city's economy, Elliott said. He said the schools during the 1977-78 academic year are spending $713.5 million, and their students are spending an additional $97.7 million. When that $811 million is respent and recycled through the economy the total impact is in excess of $1.1 billion, he told the bankers.

"What would we be willing to do to bring a billion-dollar-a-year industry to this city?" Elliott contrasted proposals to tax property owned by the colleges with the civic's support of a publicly owned convention center.

The George Washington president chose the bankers convention to release a study by the Consortium of Universities of the Washington Metropolitan Area on the economic impact that the schools make on the District of Columbia economy.

The study is intended to show that the universities are already a major factor in the city's economy and should not be forced to pay more taxes on the property they own. During the 1977-78 academic year the schools paid about $6.1 million in taxes, less than 1 percent of their spending. The property they own is worth about $500 million.

Schools in the consortium are American, Catholic, Georgetown, GaHaudet, Howard and George Washington Universities, the University of the District of Columbia and Mt. Vernon and Trinity Colleges.

Saying the colleges "will always be in some kind of beggar-like attitude," Elliott said he "shudders" at the thought of raising more money to pay taxes.

Since 1970, he said, the colleges have spent almost $500 million building and equipping new facilities. That is about what the convention center and related hotel and retail development are supposed to cost.

The convention center, it is estimated, will produce 4,000 construction jobs a year, Elliott noted.

Elliott said the nine institutions employ more than 32,000 persons in full and part-time jobs, about 15,900 of them District of Columbia residents. He said D.C. residents receive about $175 million a year of the $412 million payroll of the schools.

About one-third of the 80,700 students are resident of the District.