The Council on Environmental Quality wants to force government agencies to trim the length, complexity and prose of the often overstuffed and under-read environmental impact statements they prepare by the thousands.

The council proposed regulations this week that might - as a byproduct - guarantee compliance: federal officials would be required to read the voluminous statements.

The statements have been required since 1970 as a way of assessing the environmental effect of dams, airports, nuclear waste disposal projects, federal buildings and other public works. They have been used by environmentalists to block, postpone and alter projects and have been cursed by many businessmen as symbols of government obstruction.

Both sides, however, have tended to agree with Charles Warren, chairman of the council, that the 70 government agencies producing the reports "too frequently produced massive tomes full of barely relevant ecological data that obscured the critical issues" and buried them in paperwork and delays.

The regulations would be the first imposed on the entire federal bureaucracy, a fact which has already stirred complaints from other agencies.

In some respects, the proposed rules read like a stylebook for report writing. Most of the impact statements - some of which now require thousands of pages and even volumes - could only total 150 pages. Unusually important ones could run up to 300.

They would have to be "clear, to the point and written in plain English.. . . Verbose descriptions of the affected environment are themselves no measure" of the statement's adequacy, the proposed regulations say.

Agencies would be instructed to "avoid useless bulk" and repetition and to write reports which are "analytic rather than encyclopedic . . . There shall be only brief discussion of other than significant issues."

Businessmen and others, who have watched costs of a project balloon with inflation while waiting for completion of an impact statement, would be entitled to guaranteed time limit from the government agency working on the report.

Ultimately, someone in the agency would have to read the impact statement because the new regulations would require a response: a formal document setting out which of the many choices presented by a project is environmentally most desirable.

While impact statements consuming thousands of pages are not uncommon, the problem has often been illustrated with an extreme example: the report on the natural gas pipeline constructed in Alaska required 17 volumes, 9,570 pages and weighed 40 pounds.

Preparation of the reports often costs hundreds of thousands of dollars. A new industry of report writers has sprung up to collect the fees. A December 1976 survey by the American Consulting Engineers Council found that up to 4 to 6 percent of gross revenues for their members came from preparation of the statements.

Tne new regulations would require, for the first time, that the firm or person who prepares the reports be identified, in part to prevent conflicts of interest Warren said have become all to frequent.

The council will receive comments on the proposals unitl Aug. 11. Final regulations are expected to be issued in October.