A timeline of the water crisis in Flint, Michigan

Flint seeks an evaluation of its efforts to improve the water amid concerns that it contains potentially harmful levels of a disinfection byproduct.

Flint residents snap up 200 cases of bottled water in 30 minutes in a giveaway program.

State officials pledge $2 million for Flint's troubled water system.

Flint officials say the quality of its water has improved and that testing finds the water meets all state and federal standards for safety.

SEPT. 24: A group of doctors led by Dr. Mona Hanna-Attisha of Hurley Medical Center urges Flint to stop using the Flint River for water after finding high levels of lead in the blood of children.

Snyder announces that the state will spend $1 million to buy water filters and test water in Flint public schools.

Snyder activates the Michigan National Guard to help distribute bottled water and filters in Flint and asks the federal government for help.

Obama signs an emergency declaration and orders federal aid for Flint, authorizing the Federal Emergency Management Agency and the Department of Homeland Security to coordinate relief efforts, but denies the request for a disaster declaration.

During a Democratic debate, presidential candidate Hillary Clinton criticizes Snyder for his handling of the water emergency and her rival, U.S. Sen. Bernie Sanders, notes his call for Snyder's resignation.

The governor also releases more than 270 pages of emails about the Flint water crisis that show debate over who is to blame and offer insight into the state's response.