The D. C. City Council yesterday enacted legislation gving the mayor broad emergency powers to curtail business hours, shut retail stores and turn down thermostats in private dwelling during extreme fuel shortages such as that of last winter.

Mayor Walter E. Washington said he intends to sign the measure.

Last winter, when Mayor Washington lacked specific authority to impose mandatory energy curtailments on private users, he issued a series of "statements" and "recommendations" urging citizens to reduce fuel consumption on a voluntary basis. He claims the appeal resulted in a 12 to 15 per cent energy use reduction during the severe cold of last January and early February.

The National Weather Service has tentatively called for a colder than normal winter though not as severe as last winter. Federal Energy Administration analysts have said residential customers should have adequate suppliers of natural gas. Gas industry leaders, however, are not as optimistic and say a shortfall between supply and potential demand remains.

The measure adopted by the City Council yesterday is similar to fuel emergency legislation already on the books in most states and was modeled after the law in Maryland.

The new District law empowers the mayor to declare a public emergency for up to 15 days if the city is "threatened by reason of an actual or impending acute shortage in usable energy resources."

During the emergency period according to the measure, the mayor may order "any person or group or class of persons . . . to reduce or otherwise alter the hours during which they conduct business or similar activity established and maintained for business, public or other purpose."

He can also order persons to "adjust temperature requirements" and use lower grade heating oil even if it violates clean air standards during the emergency period.

Assistant Corporation Counsel John Salyer, who helped draft the legislation, says its language effectively permits the mayor either to curtail private business hours or to shut down business entirely in extreme situations.

It also empowers the mayor to order temperatures lowered in private dwellings, according to Salyer and Bruce French, staff director of the City Council's government operations committee. While temperatures in apartment buildings could be controlled through centrally located thermostats. Salyer acknowledged that enforcement of temperature reductions in private detached houses would be difficult.

If the fuel shortage emergency continues beyond the 15-day period declared by the mayor, the mayor's emergency powers can be extended only by emergency legislation by the City Council.

The measure does nor change the present authority of the D.C. Public Service Commision to authorize the Washington Gas Light Co. to curtail gas to nonessential commercial or industrial users during emergency periods, as the utility did last winter.