More than 50 years after the Kennedy administration found that the National Park Service had a single black ranger and bemoaned a serious lack of diversity in the federal conservation corps, not much has changed at public and private organizations that serve as stewards of the environment, according to a survey.

A report released last month said the nation’s large, powerful and decidedly liberal green groups have failed to keep pace with the nation’s expanding minority populations and remain overwhelmingly white.

Minorities represent nearly 40 percent of Americans, yet account for fewer than 16 percent of workers at the government agencies, nongovernmental organizations called NGOs and foundations that were studied.

The divide has resulted in two environmental movements. One is white and the other non-white, one rich and the other poor, one devoted largely to advocating on behalf of wilderness areas and the other for “environmental justice” in core urban areas where minorities tend to live.

“The current state of racial diversity in environmental organizations is troubling, and lags far behind gender diversity,” said the report, “The State of Diversity in Environmental Organizations: Mainstream NGOs, Foundations, Government Agencies.” But the gender gap, it said, was closed by hiring women who are largely white.

People of color comprise 36 percent of the U.S. population, 29 percent of the science and engineering workforce and only 16 percent of the staff in the environmental organizations surveyed. (Green 2.0)

It is the first investigation of diversity within green groups in years and, experts said, the most comprehensive. And it was endorsed as accurate by many white, black and Latino directors and staff members in the field.

“Sierra Club supported it, financially as well,” said Leslie Fields, the environmental justice director for the club. Even as the groups make limited progress in minority hiring, the study’s criticism “needs to be said,” said Fields, an African American who’s worked at the club for seven years. “We know we need to do better.”

The study was suggested by Robert Raben, founder of the Raben Group, a lobbying organization, and a former U.S. assistant attorney general, who walked into a environmental gala several years ago and was surprised that the few non-white faces he saw were on the staff of waiters.

The survey was funded by Green 2.0, which calls itself “an initiative dedicated to increasing racial diversity across mainstream environmental nongovernmental organizations, foundations and government agencies.”

The research was undertaken by Dorceta Taylor, a professor in the School of Natural Resources and Environment at the University of Michigan. Taylor found that of the 3,140 paid staff members at large groups such as the Sierra Club, Natural Resources Defense Council, Nature Conservancy, Environmental Defense Fund, National Wildlife Federation and Earthjustice, 88 percent were white. On the boards that govern the groups, 95 percent of members were white.

“Numbers don’t lie,” Taylor said in a statement. “People of color only represent 12 percent of staff at foundations, 15 percent of staff at government agencies and 12 percent of staff in mainstream environmental NGOs,” and until this year, “none of the largest organizations had a president, vice president or assistant/associate director who was an ethnic or racial minority.”

Taylor wrote that an “unconscious bias” exists within the liberal and progressive culture of the groups, preserving a racially homogenous workplace. “Recruitment for new staff frequently occurs through word-of-mouth and informal networks,” the study said. “This makes it difficult for ethnic minorities, the working class, or anyone outside of traditional environmental networks to find out about job openings and apply for those jobs.”

Minorities who are employed often feel alienated, according to a section of the report that interviews past and present workers who are black, Latino, Asian and American Indian.

“You ask them what needs to happen internally . . . and 77 percent say they want to recruit, but only 48 percent say staff training should be done,” said Danielle Deane, a principal in the Raben Group. “They don’t recognize what they need to make people of color feel welcome. People are well intentioned, but their plans aren’t the best.”

Fields said minorities at large green groups describe themselves as “onesies and twosies,” reflecting the one or two non-white people on the staffs. “It’s the culture,” she said.

The battle over diversity was joined in the 1970s when the federal government created broad regulatory powers to clean polluted air and water and protect entire species of animals that were disappearing from wildlands, fresh waters and oceans.

As the modern civil rights movement entered its third decade, black, Latino and Asian advocates sought to join mainstream environmental organizations to battle the power plants, petrochemical refineries, railroads, sewers and other polluters operating in their communities.

By and large, they found they were unwelcome in an “environmental movement that had been white and upper middle-class,” the report said.

Minorities started using hallmarks of the environmental cause to advocate for issues that affected their communities, and against what they viewed as exclusion from mostly white government agencies, as well as nongovernmental groups and the white foundations that funded them almost exclusively.

On Earth Day in 1970, “minorities used the events . . . as opportunities to draw attention to issues related to people of color and the poor and the environment. Once again, environmental inequality and diversity were at the top of the agenda,” the study said.

Two decades later on the 20th anniversary, it was still an issue, and at a first-ever summit of minority environmentalists held in Washington in 1991, letters were issued to green groups condemning their poor diversity while garnering the lion’s share of funding that could help minority communities.

The largest green groups were split on an explanation. Some said they tried to be more inclusive, but minorities lacked the education and skills needed to be effective advocates, recruiters said.

But the study quoted Fred Krupp, president of the Environmental Defense Fund, who had the opposite take: “The truth is that environmental groups have done a miserable job of reaching out to minorities,’’ he said.

In recent years, every group mentioned in the study worked harder to recruit minorities and succeeded in some ways. But they are finding it hard to retain them. That was true at the Environmental Protection Agency, said Lisa Garcia, a vice president at Earthjustice who once worked there.

“While I was at EPA, there was a huge push to bring diverse candidates to higher levels, to management positions and leadership positions,” she said. But retention became a problem because white managers struggled with the question of “how to make it a comfortable place to work,” she said.

At Earthjustice, the same questions arise, said Garcia, who’s Latina, and the solution is clear as the organization strengthens its diversity aims. “Being here made me realize the commitment needs to be a little deeper, and we need to have the harder conversation.”

That conversation is about a culture where minorities who want to target work toward communities and away from wilderness issues are often dismissed, even shunned.

“This is not rocket science,” said Angela Park, founder and chief executive of Mission Critical, a nonprofit, and a member of the Council on Sustainable Development during the Clinton administration.

“It’s going to take time, obviously,” she said, but the “speed of the change and pace of the work needs to speed up. Just because you’re progressive doesn’t mean you don’t have unconscious bias ingrained in the culture. We are never going to solve the problems without all our communities represented.”