Two women who sounded early and persistent alarms about the quality of the water in Flint, Mich., will receive the Freedom of Expression Courage Award from PEN America, the group announced on Friday.

LeeAnne Walters, a mother of four whose children were poisoned by lead in the Flint water supply, and Dr. Mona Hanna-Attisha, a pediatrician who revealed high levels of lead in the blood of children in the city, will be honored at the annual PEN Literary Gala on May 16 in New York.

“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,” Suzanne Nossel, the executive director of PEN America, said in a statement.

The award was created in 2014 to honor “exceptional acts of courage in the exercise of freedom of expression.” It was given to the staff of the French satirical newspaper Charlie Hebdo in 2015.