For the owners at the Lynnhill condominiums in Prince George's County, the dream of home ownership has turned into a nightmare of decaying buildings, huge condo fee increases and numerous foreclosures.

A few miles away, the owners at the Brookside Park apartments are trying to grapple with their serious financial bind.

An estimated $1 million is needed to repair basic defects, such as leaky roofs and rusting balconies, and their reserve fund has only a small fraction of the money needed to pay for them.

For those owners and other moderate-income buyers here and throughout the country, the condo boom of the 1970s may become the condo bust of the 1980s, housing experts say.

"You're just going to see an explosion of problems soon," predicts Benny L. Kass, a Washington lawyer who represents a number of condominium groups.

The first and worst of these problems will be at older rental apartment buildings that underwent quick, cosmetic conversions in the early and mid-1970s. These are coming to the end of their useful lives, and costly structural repairs will be required. There are many condominium units that fit this description in Prince George's County and Northeast Washington, local experts say.

But there is a message here, too, for higher-income owners of both conversions and newly built condominiums: those who haven't put enough money aside or who have not seen that proper care is taken of their buildings will face a dilemma on how to pay large bills for major repairs as their condos approach middle age.

The only way the bills can be paid are with special assessments or large jumps in monthly condo fees, which are supposed to cover services and repairs on the buildings and grounds. In cases where the owners are assessed but cannot pay, they would go into default and could lose their homes.

Condos that have not been well managed and well financed "will become future slums," predicts Arthur Hiban, president of Hiban, Graffius and McKee Ltd., a community management company. When this happens, foreclosures will be extensive and investors will pick up apartments at bargain prices and turn them back into rentals, Hiban said.

There now are about 95,000 condo units in the Washington area. About 50,000 units were built or converted by the end of 1976, according to the Washington Metropolitan Council of Governments.

Just how many of these condominiums are headed for serious trouble is difficult to assess, the experts say, because there are so many variables, including luck, in that equation. But some specialists say virtually no condominium has covered itself fully.

"Less than 10 percent of the condo associations in the Washington Metropolitan area have 100 percent of their reserve requirement in the bank," said James Dowden, executive director of the Community Associations Institute, which has both developers and owners as members. As many as 10 to 15 percent of the condominium projects in this area could be headed for serious trouble, Hiban adds.

A few worst-case examples of different types of problems have surfaced already:

At the 219-unit Lynnhill high-rise in Temple Hills, the owners' condo fees jumped by 50 percent recently and now are higher than their mortgage payments and out of reach for many. About half the owners have been delinquent on their condo fee payments for the past several years--one reason there was no money to make basic repairs. Now the roofs are leaking, the electrical system needs to be replaced, and the crime problem has risen dramatically because of cutbacks in security measures.

The units are virtually unsaleable because lenders won't provide new mortgages in view of the increased risk of defaults and the decline of property values. Foreclosure proceedings have been started against many Lynnhill owners to force payment of fees so the association can get enough money to start making repairs. But the more the fees are raised, the more difficult it is for the owners to pay.

At the 552-unit Brookside Park, repairs estimated at $1,800 per unit have to be made soon, and the moderate-income owners don't have the money in their reserve funds. Fees were held down since the 1973 conversion, and the association also tapped its reserve fund for normal operating costs. Earlier this year the community revolted against a plan to raise condo fees so that the roofs could be repaired right away, and a new board has vowed to keep the fees down. Brookside Park has not deteriorated as severely as Lynnhill, but the owners have taken steps geared to keeping their monthly costs down while their need for large capital expenditures can only continue to rise.

Even luxury condos are not immune from these kinds of financial shocks. Owners at The Representative, an Arlington high-rise, were confronted with $2 million in unexpected repairs recently, including $1 million in work needed on the outside wall of the building. The developer disclaimed responsibility.

But The Representative, where units are now priced around $300,000, is not in trouble. The upper-income owners merely assessed themselves $10,000 each to make the repairs, and work has started. "Nobody is too happy about it," and they still are trying to get the money from the developer, but everyone is paid up, said condo association president Stanley Rosenbluth.

Between the Lynnhill example and The Representative, there is a wide range of condos where owners would be unlikely to lose their homes because of inability to pay their fees but where they could face sudden large assessments.

In the early days of condominiums, the fights were first between condo converter and apartment tenants trying to avoid eviction. Then the battles were between developer and new buyers over workmanship and decision-making at the development. Now disputes increasingly are between owner and owner, sometimes divided along the lines of resident-owners and investor-owners, as they try to make joint decisions on how to work their way out of financial or other difficulties.

But the developer was responsible for starting the condo off right. In the early and mid-1970s, either through lack of experience with condominiums or merely because they wanted to sell out quicker, developers often "low-balled" the condo fees, setting them at lower rates than were needed to establish an adequate reserve fund, condo specialists say.

"It was not until the recent years, maybe the last five, that the industry has realized the need to set aside capital reserves" to take care of major repairs and replacements, the condominium institute's Dowden said.

After the developer left, many condo owners were shocked to discover that the fees had been set too low, and then they had to decide whether to raise their own fees.

"When I represent a condominium, the first thing I ask to see is the budget. That's how you see what kind of reserves there are," condo lawyer Kass said. "But people don't look at these things. They are swept in by the promises. The developer says, 'We'll give you a free chicken,' and they buy it."

The situation is better now for the condo buyer than it was in the early and mid-1970s. Developers are more experienced with condos and can plan better; today's "second-generation" buyers are more familiar with condo ownership and have a better idea what to look for, and states started to establish some legal protections in the late 1970s.

In addition, secondary markets that buy condo mortgages, the Federal National Mortgage Association and the Federal Home Loan Mortgage Corp., now require adequate reserves before they will invest, a strong incentive to local lenders and developers to establish them properly.

But generally the buyer is still on his own to protect himself. Several states have approved laws relating to the sale of condos now, but almost all of these require only disclosure of such items as budgets and reserves, not that these be done properly. This leaves it up to the buyer to sift through the hundreds of pages in the public offering statement and analyze whether the developer budgeted well or "low-balled." This is true in the three jurisdictions in this area, though Virginia's disclosure requirements are more stringent than in Maryland or the District, condo lawyers say.

Dowden of the Community Associations Institute said condo buyers now are more informed than they were when Lynnhill was converted, but this is small comfort to those only now realizing the mistakes made when they bought years ago.

"Slowly but surely the word is getting out that there is a way to go about this business," Dowden said. "But as in all things, it's going to take a while. It will not be without its pain, and there are going to be some condo owners who will be lost."