CULLEN JONES and Lia Neal were among the many swimmers to win medals for the United States in this year’s Olympic Games. But their inspiring performances obscure a disturbing truth. Not only are they, as African-Americans, anomalies in the elite levels of their sport, but enormous numbers of African-Americans do not have even rudimentary swimming skills, a lack that costs lives.

A 2010 study by the USA Swimming Foundation and the University of Memphis reported that nearly 70 percent of African-American children do not know how to swim. According to the Centers for Disease Control and Prevention, African-American children between the ages of 5 and 14 are almost three times more likely to drown than white children.

Cullen Jones could have been one of them; his parents put him in swim class after he almost drowned at the age of 5. Jones has become an evangelist for the importance of swimming lessons, working with Make a Splash, a water-safety initiative focused on minority children. But it can be tough even to give swimming lessons away. Starting last fall, the Boys and Girls Clubs of Boston made swimming lessons mandatory for their members, who are predominantly black and Hispanic. Though the lessons were free of charge, a number of parents had to be talked into allowing their children to participate: they were terrified of letting them get in the water.

This bears out the USA Swimming Foundation’s finding, in its 2010 report, that “fear trumped financial concerns across all respondent race groups in low-income families.”

Regardless of race, the poor lack access to pools and swimming lessons. Around 40 percent of white children and 60 percent of Hispanic children do not know how to swim — they, too, could benefit from free or affordable lessons. But why is the problem worse among African-Americans, many of whom, across all economic classes, lack confidence in the water? A large part of that unease is a legacy of slavery and segregation.

It has been documented that before slavery, many West Africans could and did swim. But a slave who could swim was a slave with another means of escape, so slave owners went to great lengths to make it impossible to keep this skill alive.

Later, segregation took its ugly toll at public beaches and pools. According to the historian Jeff Wiltse in an NPR interview, “whites set up, essentially, sentinel guards at the entrance to the pool, and when black swimmers tried to come in and access them, they were beaten up, sometimes with clubs.” One white motel manager was caught on camera pouring acid into a pool in which blacks were staging a “swim-in.” Institutionalized racism was shored up by specious scholarship, like a 1969 report titled “The Negro and Learning to Swim: The Buoyancy Problem Related to Reported Biological Difference.”

Sadly, the fear of water that was instilled in African-Americans back then has become self-perpetuating. “Don’t you know blacks don’t swim?” Jones remembers being told by members of his family. It’s time to bury that stereotype at sea. As of 2010, 15 European countries had made swimming a compulsory part of their education curriculums. Ideally, the United States would do the same. Not likely, I know, when even dry land physical education programs are being slashed. But we can and should do better.

This country is blessed with a network of community centers like the Y.M.C.A. and the Boys and Girls Clubs that have swimming programs, instructors and pools in place. These centers could take Boston’s example and make swimming lessons mandatory, which would benefit their clientele, regardless of its racial makeup. Public schools (and particularly charter schools, many of which have extended their school years into summer’s heat) could devote part of each summer to shuttling their students to swim programs.

Another model is the public-private partnership, like Horizons National, an academic summer program that partners low-income schools with independent schools and colleges that have access to swimming pools. Here’s a quote (posted on the program’s Web site) from one participant: “When I started Horizons I was so afraid of the water that I would not even go in the shallow end. Learning how to swim and overcoming that fear helped me realize that I could do anything.” Who said this? Algernon Kelley, who now has a Ph.D. in chemistry and lectured at Xavier University of Louisiana.

The best way to eliminate the culture of anxiety around swimming is to create thousands of little African-American swimmers who are not afraid. I was one of those swimmers — never elite but always joyous. My parents packed me and my siblings off to the pool at our local community center as soon as we were old enough, and I became the kind of kid who would get out of the water only when my lips were blue. How wonderful if more children could feel the joy and confidence I feel when I’m swimming — and be safer around the water, too.

The United States faces immense problems of all kinds, many of which are more pressing than teaching children to swim. But for a mother who stands screaming on the shore as her child goes under for the last time, not knowing how to swim is the biggest problem there is.