In a ruling that could apply to many sports, a federal appeals court says the governing body for water polo in the U.S. can be sued for failing to protect an athlete from serious head injuries by letting her return to play after she suffered a concussion.

Sports organizations and managers of recreational areas cannot be sued for injuries that are considered an inherent part of the sport, like a hard tackle in football or a hit batter in baseball. But injuries to a player who is sent back to the pool after a concussion are not “an inherent risk in water polo,” and the sponsoring agency, USA Water Polo, can be held responsible, the Ninth U.S. Circuit Court of Appeals in San Francisco said Wednesday.

The ruling reinstated a class-action suit by a Livermore woman whose teenage daughter was injured at a tournament organized by USA Water Polo in February 2014. Steve Berman, a lawyer for the family, said the ruling should be “a wake-up call for all sports” and “could have life-changing impacts for those facing lifelong repercussions of traumatic brain injuries.”

There was no immediate comment from lawyers for USA Water Polo. The organization oversees more than 500 teams, including the U.S. national team, and more than 400 tournaments each year.

The court said the teenager, identified as H.C., was playing goalie for Livermore’s Lazers team at the tournament in Los Alamitos (Orange County) when she was hit in the face by a ball. According to the suit, H.C. was dazed, swam to the side of the pool and talked with her coach, who asked her a few questions and then sent her back into the game.

Later that day, she played in more games and was struck in the head several more times. The coach had not received any instruction or training from USA Water Polo on dealing with concussions, the suit said.

Two days later, the suit said, H.C. started suffering headaches and severe fatigue and was unable to attend school, where she had been a straight-A student and a multisport athlete. She was diagnosed with post-concussion syndrome, suffered a decline in mental capacity, and, as of 2016, had been unable to return to school, the suit said. Her lawyers declined to comment on her current condition.

A federal judge in Los Angeles dismissed the suit in 2016, saying head injuries were part of the risk of playing water polo. But the appeals court said USA Water Polo, though not legally responsible for H.C.’s initial concussion, might have prevented further injuries with rules that had kept her from returning to the game.

The organization actually passed such a rule in 2011 for its national team, requiring medical evaluation of any player who has suffered an apparent concussion or other serious head injury and prohibiting their return to play on the same day. For other water polo teams, the court said, the organization has vaguely written standards, in “fine print,” that merely advise coaches not to let an athlete return to play after a serious injury such as a concussion.

Based on the allegations in the suit, USA Water Polo “increased the risk of secondary concussions to players who improperly returned to play,” Judge William Fletcher said in the 3-0 ruling. The suit also contends that the organization “was well aware of the severe risk of repeat concussions,” Fletcher said, citing allegations that parents and educators, and USA Water Polo’s insurance company, had been urging the organization for years to establish stronger protections.

The court also noted California rulings that have rejected a suit by a college baseball player who was hit in the head by a deliberately thrown “beanball” from an opposing pitcher, but allowed a suit against a baseball stadium owner who had failed to take reasonable steps to protect fans from injury caused by a bat that slipped out of a player’s hands and sailed into the stands.

“Injury from a flying bat at a baseball game and from returning to play in a water polo game can be minimized or eliminated,” Fletcher said.

Bob Egelko is a San Francisco Chronicle staff writer. Email: begelko@sfchronicle.com Twitter: @BobEgelko