A new report has criticized D.C.'s efforts to provide affordable housing, saying the Gray administration hasn't held up the standards set by previous mayors, even as the city's home prices continue to skyrocket and the income divide grows.

The report calls on the city to mandate that 30 percent of housing units in projects on D.C. land be set aside for families who make less than the region's median income, which is $107,500 for a family of four. Currently, affordable-housing levels are set by the city on a project-by-project basis. The report was produced by the Coalition for Smarter Growth, which advocates walkable communities.

While the city has set "an impressive record on affordable housing" in public land redevelopment, the report issued last week says that under Mayor Vincent Gray, "requests for proposals have reduced required set asides for affordable housing in public land development deals compared to the previous decade."

But other experts say the housing landscape isn't that simple, as prior mayors have ruled in real estate booms.

"During the boom times, you could get away with a lot simpler approach. But right now you really need to work to find what the right numbers are," said John McIlwain, a housing expert at the Urban Land Institute.

He added that a 30 percent requirement wouldn't be feasible in many projects today unless the city could compensate developers for that loss.

A spokesman for Gray said the report was one-sided.

"I think folks forget and don't see all the work we're doing on the other end -- strengthening D.C. Community College and One City One Hire," said Pedro Ribeiro. "Those pieces are just as important as creating units."

Still, home prices in the city continue to climb -- median sale prices have increased by 10 percent to nearly $420,000 since last September, according to the latest housing report from George Mason University. Meanwhile, U.S. census figures show the income gap in the District has gotten bigger in the post-recession era. The difference between the wealthiest households and the poorest in the city in 2009 was $71,000. Now, the gap has widened to more than $125,000 as the median income in the city's wealthiest neighborhoods are more than $155,000.

Staffers of at-large D.C. Councilman Michael Brown said he agrees that the city needs to provide more affordable housing. Brown, who chairs the council's housing committee, worked with the Department of Housing and Community Development to focus funding for affordable housing on those who earn less than 80 percent of the region's median income.