A doctor credited with bringing Flint's water crisis to light after state agencies initially dismissed her concerns told Michigan State University graduates Friday to "raise your hands" and fight for justice.

Mona Hanna-Attisha, who spoke at the undergraduate commencement ceremony, said things are improving in the struggling Michigan city because residents, journalists, researchers and others have spoken out about the lead-tainted drinkinger water.

The Hurley Hospital pediatrician reported high levels of lead in the blood of children and pleaded with the public to stop drinking the water, which had been releasing lead from old pipes. Gov. Rick Snyder eventually acknowledged what she found and gave her full credit.

"When you are fighting for your community, fighting for the future of your children, you do not put your hand down," said Hanna-Attisha, an assistant professor of pediatrics at Michigan State University's College of Human Medicine. "We kept our voices loud and we kept our hands up — so high and now there were so many of us — raising our hands with the moms, the journalists, the scientists. And finally, there was no way to ignore us. Anywhere and everywhere they looked, they saw our hands, they heard our voices and finally things started to happen."

The city, in an effort to save money while under state management, began drawing its water from the Flint River in April 2014. Despite complaints from residents about the smell and taste and health problems, city leaders insisted the water was safe. The source of the city's water has been switched back to Detroit, but the lead problem still is not fully solved.

President Barack Obama, who spoke Wednesday in Flint, declared a state of emergency in the city in mid-January and ordered federal aid to supplement the state and local response. Most people are drinking filtered or bottled water.

An independent commission appointed by Snyder determined the state was primarily responsible for the contamination, and he issued an apology. The Obama administration's response, through the Environmental Protection Agency, has also come under criticism from Snyder and some in Congress who say the EPA didn't move with necessary urgency.

Attisha is expected to receive the Freedom of Expression Courage Award this month from PEN America, a prominent literary and human rights group.

She told graduates she sees better days ahead for Flint but remains angry because "this never should have happened." She encouraged them "not to fear being the dissenter, whether you are fighting big or small injustices."

"The issue may not be as momentous as the poisoning of a town, but there are Flints everywhere — there are injustices everywhere," she said. "There are places and people that will need you to raise your hand."