Charlene C. Harris hoped to live out her years at 1600 Colorado Ave., the single-family brick cottage that she and her family have called home for 47 years.

But now the retired 68-year-old state employee is being told she must either purchase the two-bedroom home from her landlord, the Richmond Redevelopment and Housing Authority, or face moving.

“It’s a terrible situation,” she said. “RRHA has told me I have to put up $500 to begin the process and to get a mortgage by December. Otherwise, I would have to accept relocation.”

Like other public housing tenants of such homes, she feels caught in a Catch-22. Until she puts up the $500, RRHA won’t provide an appraisal that would let her know what the sales price would be so she could figure out if she could afford the house on her fixed income of about $1,500 a month.

It is an ironic twist that RRHA is now marking its 75th year of operating public housing by reviving a plan to cut its inventory of units.

The goal: To get rid of the remaining 110 single-family housing units that once ranked among RRHA’s premier places to live.

Many of the houses, like the one Ms. Harris occupies in the Randolph area, are among dozens that RRHA bought and moved out of the construction path of the Downtown Expressway in 1968. Others were purchased in various neighborhoods until 1977.

Overall, the experiment created RRHA’s first mixed-income neighborhoods, with public housing residents living side-by-side with people of higher incomes — the goal of every development with which RRHA is now involved.

“It may have been a good idea at the time,” said T.K. Somanath, interim RRHA executive director. But today, with Congress shrinking maintenance dollars for public housing, “keeping them up is cost prohibitive. We just don’t have the money.”

According to RRHA, the federal funding it receives for maintenance of its properties has dropped from around $7.7 million a year to below $5.7 million annually.

The authority previously estimated that its inventory of single-family units would need about $1.1 million in maintenance a year, but that it would have only $260,000 a year to put toward that purpose.

Many of the homes still lack modern central heating and air conditioning systems and have outdated electrical boxes and plumbing that needs replacement. Even so, city tax assessment records indicate many are valued around $100,000.

RRHA has long considered the aging houses a liability, particularly with the rents fixed and the cost of repairs going up.

Nine years ago, RRHA planned to spend $8.5 million to modernize the houses and then sell them to tenants, but that effort never materialized.

In 2007, RRHA received permission from the U.S. Department of Housing and Urban Development to sell the houses “as is” at fair market value to the tenants. But the Great Recession then collapsed the mortgage market and RRHA’s plans to renovate the properties to improve their condition.

The goal then and now was to shift the onus for maintenance to new owners, whether the tenants or others who purchase the houses.

Ultimately, only 11 of the houses were sold, and RRHA put the sales program in limbo during the tenure of Mr. Somanath’s predecessor, Adrienne Goolsby, after Ms. Harris and others complained.

Last month, Mr. Somanath lifted the moratorium. Along with notifying Ms. Harris and other tenants about the need to buy, he also is moving to seek HUD’s permission to sell the properties to any willing buyer if the tenants do not purchase them or to demolish them.

The approvals could take six or more months to secure, but Mr. Somanath is confident that HUD ultimately will give the green light.

Mr. Somanath said RRHA no longer can sit on the vacant houses that blight the areas. At this point, 66 of the 110 units are boarded up, he said, with little prospect of RRHA ever being able to fix them up, given the estimated $40,000 to $50,000 cost.

The remaining 44 units are occupied, with some of the houses still needing substantial work, Mr. Somanath said.

“The sales program has been on and off for some time. We need to bring it to closure,” he said.

He said he wants tenants to put up $500 to prove they are serious about purchasing. He said in the past, some tenants agreed to purchase, then backed out after RRHA made improvements to their houses.

However, he said RRHA is willing to work with tenants. Among other things, RRHA can offer a $20,000 second mortgage that would disappear if the resident continued to live in the house for a certain number of years. Down payment assistance also could be possible, or at least provide a reduction on the price, he said.

“If there is a willing buyer, then we can work on getting the financing in place,” he said. He said RRHA also would be willing to have tenants work with Housing Opportunities Made Equal and similar home counseling groups to help craft contracts.