The state of Maryland is looking for a few good pieces of land.

They should be about 500 acres in size, near a divided highway and far from heavily populated areas. Tight soils, especially clay, are highly desirable. Any spot in a major watershed, wetlands or where water flows just beneath the surface is out.

The right parcel gets the prize: a hazardous waste dump.

For the past year, a crew of geologists, consultants and specialists with the Maryland Environmental Service (MES) has been combing the state for at least one disposal site for an estimated 300,000 tons of hazardous waste generated each year by Maryland industries, mostly clustered around Baltimore. The experts are midway through the process of winnowing out unsuitable land, but no specific dump sites have been named yet.

Early indications are that Montgomery County may be spared because of possible danger to the water supply, and because of its extensive park land and densely populated areas. On the other hand, nearly a quarter of Prince George's County is still in the running.

Choosing the sites is a game of elimination with potentially deadly consequences. "Toxic waste" evokes horror stories about PCBs, Love Canal and derailed freight cars spilling carcinogenic chemicals in populated areas.

Last year at this time, clouds of white poisonous vapors leaking from a chemical waste drum forced the evacuation of 150 students from the university of Maryland's chemistry building. Just the application last August by a New York firm to construct a toxic waste facility near Laurel provoked a buzz saw of opposition.

And while final choice of a site is a year and many public hearings away, the fear the lethal chemicals and the unseen threat associated with toxic-wastes already has some sections of the state up in arms.

Cecil County, nervous because of its proximity to Baltimore's chemical plants, has threatened to sue the state if the disposal site winds up within its borders.

Betty Violet, who lives in the small town of Rohersville in Washington County, has been organizing her community for the past month. She knows the state workers in Annapolis have not picked a spot, but CATCH (Citizens Against Toxic Chemical Hazards) will keep them out of her neighborhood, she hopes.

"We feel the poison and chemicals would get into our water supply and they're essentially indestructible," she said. "And if it gets into our water, pretty soon it will show up on dinner tables in Washington, because we're right at the mouth of the Potomac."

In Montgomery and Prince George's, environmental planning specialists reported that state workers have contacted them at least twice.

"At this point, we haven't received any sites to react to," said Dominic Motta, principal environmental planner for the Maryland National Capital Park and Planning Commission in Prince George's County. "I'm sure there will be plenty of reaction when they are announced."

With two of four review stages finished, nearly all of Montgomery County has been eliminated from further scrutiny, and the remaining regions hug heavily populated areas north of Washington. State geologists and engineers first reviewed environmental features last fall. The entire western half of the county and most of the northern sections were counted out as potential toxic waste sites because water supplies might be contaminated by the wastes. All park lands, which also dominate Montgomery County, were withdrawn.

Maps published after the second level of scrutiny depict remaining potential areas that include Bethesda, Silver Spring, Wheaton and regions extending north to Sandy Spring. Ann Sloan, the MES staff specialist directing the site search, predicted those areas also would be withdrawn because of the population density.

David Sobers, the Montgomery environmental planner, said some county land around an existing sludge landfill on Ednor Road might have qualities suitable for the state facility.

In Prince George's, a broad swath of land from the Bowie area cutting diagonally south and west past Andrews Air Force base to the Virginia border has been eliminated by state searchers, but other pockets in the north and east remain as potential waste sites.

Populated areas around Cheverly and Bladensburg probably will be removed from consideration, according to Sloan, but a region on both sides of Rte. 301 from Kidwell's Corner to Wells Corner together with another area further south are likely to remain past the third elimination round.

When the state reaches the point of suggesting actual sites, as it's expected to do by the end of the summer, Sloan promised public hearings in each of the affected counties.

"We really think the risk to people around the facility is negligible," said William Sloan, Ann's husband and the person in charge of MES's study of where and how much waste is generated. "It's smaller than driving to work or smoking."

The Arthur D. Little consulting firm, which studied the situation, paints a different picture, however. After outlining threats of fire, explosions, polluted drinking water and contaminated food as some risks associated with disposal of toxic wastes, the consultants said many problems can be overcome, but concluded: "Nonetheless, the buried wastes are expected to remain hazardous forever. The potential risks (type of event, likelihood that it will occur, and severity if it does occur) are presently unknown."

The federal authority for Maryland's movement on the hazardous waste front stems from the Resource, Conservation and Recovery Act of 1976. That year, the state passed a law to regulate toxic waste disposal and last year, the General Assembly passed the Hazardous Waste Facility Siting Board Act.

The eight-member board established by the law holds regular meetings in Annapolis. It commissioned the Maryland Environmental Service with a 1981 budget of $300,000 to find out how much waste is produced in the state and where to put it. The law empowers the board to overrule local zoning restrictions against toxic dumps.

Allied Chemical Corp. in Baltimore, the company that lobbied hard for the current disposal siting law, produces nearly half the hazardous waste in the state, according to the consultants. Of the 348 companies that manufacture toxic substances as a byproduct, only nine generate more than 2,000 tons a year.

While toxic waste in the state runs the gamut from cyanides to acids to solvents, Allied Chemical's yield of spent chrome ore tops the list for quantity at 114,000 tons last year. Listed as an "experimental carcinogen" by the authoritative book "Dangerous Properties of Industrial Materials," this metallic substance washes easily into water and can cause skin ulcers and perforated septums.

Allied Chemical's disposal site at Hawkins Point in Baltimore is running out of room, according to the Sloans, and the state's only commercially available hazardous waste landfill at Solley Road in Anne Arundel County could close next May, when its permit and zoning variance terminate.

Montgomery County generates very little hazardous waste. Genex, a Rockville firm, disposed of 440 tons of contaminated oil last year, according to figures compiled by the state. The National Institute of Health produced 206 tons, primarily of mixed chemical liquids, and Neutron Products of Dickerson generated 224 tons of non-radioactive hazardous waste.

Prince George's County generated twice as much toxic waste as its western neighbor. Mineral Pigments Corp. of Beltsville sent 1,186 tons of solid and liquid cleaning wastes to disposal sites last year, state figures show.