Howard County's zoning board today made public sweeping changes for a proposed new comprehensive county plan that would permit development of more industrial and commercial projects - including a proposed "Great America" amusement park by the Marriott Corp.

In legal advertisements planned for publication starting Wednesday, the zoning board will announce a series of public hearings that must be held in July and August before final action is taken on the overrall plan.

Two hearings will be devoted exclusively to the Marriott theme park proposal, which is expected to attract some opposition - but not as much as in 1972, when the Washington company's initial plan was turned down.

In the case of Marriott, the only proposed zoning change would be the establishment of amusement parks as a possible use for industrial zoning districts - of which the county has only two.

General Electric Co. appliance factory near Columbia is located on one of the industrial parcels and Marriott last month signed an option for the other - located directly across Interstate 95 from the GE plant.

Marriott obtained an option on 538 acres form Chase Manhattan, Bank which acquired the land in 1972 from the Rouse Co., one the developers of the new city of Columbia.

Major differences between Marriott's 1972 and 1977 proposals include the proposed site (industrial rather than residential) and a scaled down development concept which eliminates earlier plans for separate safari and marine parks as well as a small retail center, in addition to the basic theme park.

Nevertheless, Howard County Council member Thomas M. Yeager, who also is vice chairperson of the zoning board, today took issue with his colleagues on their planned hearing schedule for the amusement park zoning change.

While the hearing procedure is legal, "I feel it does not give adequate time for preparation nor does it give sufficient time for testimony," Yeager said.

He asserted that Marriott and other parties who favor the park have been given "a decided advantage over the opponents . . . Marriott Corp. with its financial resources can make an indepth presentation within the 30 day time frame involved."

The Marriott parcel heraings have been scheduled for two Saturdays in July - July 23 and 30 - starting at 9:30 a.m. in Atholton High School. Testimony will be limited to five minutes and written comments may be submitted at the same time.

Yeager said a "fairer and more appropriate" approach would be to adopt all other zoning changes and allow a separate filing by Marriott at a later date. "This would put the focus on the one issue rather than lumping it in with the full comprehensive zonning," he added.

Now, Yeager complained, citizens that are in opposition will have to organize and raise funds during the vacation season.

The Marriott parcel is bounded by I-95, U.S. 1, and routes 175 and 32. To the west is the GE plant and to the east is the wholesale food markets of Jessup. Interchanges on the main highways already are in place or are planned for the early 1980s, which means that no additional main highway work would be needed to provide access to the proposed park.

According to Marriott officials, they are planning to invest $75 million in the Howard County park, which would be nearly identical to Great America theme parks already opened north of Chicago and near San Jose, Calif.

Data compiled by the company before some recent increases in the county's property tax and the state's sales tax project property tax revenues to Howard County of $1.87 million in the first year of operation, not counting a planned annual reinvestment in expansion of about 5 per cent.

Sales tax receipts would be $905,000 under the 4 per cent reate (scheduled to rise to 5 per cent in 1978) and admission taxes to the county would total $1.17 million.

If approved by the county, Marriott expects to begin construction next spring with an opening planned for 1980. The park would be open weekends in the spring and every day between Memorial Day and Labor Day, plus weekends thereafter until late October.

The proposed site is located midway between Washington and Baltimore - two markets which the company expects to include most of its customers. After Marriott was turned down here several years ago, it acquired land near Manassas in Northern Virginia but company officers have retained a preference for the Baltimore Washington corridor.

A Marriott spokesman said today that if the park here is approved, Marriott would sell the Northern Virginia property or develop it for light commercial use.

Howard C. Landau, executive secretary to the zoning board and county council, emphasized today that all the 69 changes being released for public study are proposals. The zoning board recently completed a series of 11 public hearings and work sessions before drawing up the final list of proposals.

Hearings on changes other than the Marriott park are scheduled for July 21, July 26, Aug. 2 and Aug. 4. In addition to the amusement park, the board has proposed more extensive commercial and business development along the 1.95 and Route 1 corridor through the county and less dense residential development in some sectors close to Columbia - because of the lace of adequate sewer and water line facilities.

More than two dozen potential uses for some commercial sectors would be prohibited by the charges, because of possibly adverse environmental consequences. Landau cited fertilizer manufacturing and plants that produce "excess odor" as among the uses elimated. Commercial airports in thecounty would be banned by the proposed changes.