A prominent literary and human rights group is giving its annual courage award to a doctor and a mother of four who faced scorn as they tried to expose dangerous levels of lead in the water in Flint, Michigan.

Dr. Mona Hanna-Attisha and LeeAnne Walters will be awarded the Freedom of Expression Courage Award on May 16 in New York, PEN America announced Friday.

“The willingness of individuals to stand up, speak out and refuse to be denied is an essential catalyst for the vindication of rights and the realization of reform,” said Suzanne Nossel, executive director of PEN America, a group of 4,400 writers dedicated to free expression. The group sparked controversy last year by giving the award to staff members who survived an attack on the French satirical weekly Charlie Hebdo.

Hanna-Attisha held a news conference last September that turned the controversy over Flint’s water into a full-fledged storm. The Hurley Hospital pediatrician reported high levels of lead in the blood of children and pleaded with the public to stop drinking the corrosive water, which had been releasing lead from old pipes for more than a year. Officials with the state of Michigan dismissed her remarks as “unfortunate” and derisively said Hanna-Attisha was adding to a “near-hysteria” in Flint. But Gov. Rick Snyder eventually acknowledged what the doctor had found and gave her full credit.

Hanna-Attisha said she’s humbled by the PEN award but insists, “I was just doing my job.”

“We knew this was a politically sensitive issue,” she told The Associated Press. “Flint was in the middle of a mayoral campaign. Hurley is a city-chartered hospital with state funding. But it never caused us to hesitate to do what we needed to do. … Our mission is service to the community.”

Walters, a former Flint resident who now lives in Virginia, knew there was nothing normal about the brown water flowing from her tap. She subsequently learned the water had extraordinary lead levels and shared a critical federal report with a reporter. Upset with the response from the state, she contacted Marc Edwards, a Virginia Tech expert in corrosion and old water systems.

Edwards and graduate students drove to Flint, took water samples and were stunned by the results.

In a statement, Nossel praised Walters for her “gutsy perseverance in the face of … willful ignorance” by the government.

In 2015, the courage award for Charlie Hebdo sparked a spirited debate about free expression among PEN members. Some skipped the spring gala, saying some of the magazine’s cartoons were offensive to Muslims.

The group will also award “Harry Potter” author J.K. Rowling this year for rousing a love of literature among children.