The Latest on the lead-contaminated water crisis in Flint, Michigan (all times local):

9 a.m.

A doctor and a Flint mother will receive a courage award from a prominent literary group for their work in exposing the lead contamination in the Michigan city's water.

Dr. Mona Hanna-Attisha and LeeAnne Walters will be awarded the Freedom of Expression Courage Award from PEN America on May 16. The group of writers dedicated to free expression and human rights made the announcement Friday.

Hanna-Attisha last fall reported high levels of lead in children, findings that eventually caused the state to take action. Walters' water was contaminated by lead. She alerted a Virginia Tech expert who took samples around Flint and was shocked by the results.

Corrosive water from the Flint River was leaching lead from old plumbing for more than a year.

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7:45 a.m.

Crews in Flint are starting to dig up old lead pipes connecting water mains to homes as part of efforts to allay the city's contaminated water crisis.

Mayor Karen Weaver says work starting Friday will target lead service lines at homes in neighborhoods with the highest number of children under 6 years old, senior citizens, pregnant women, people with compromised immune systems and homes where water tests indicate high levels of lead at the tap.

On Thursday, a crew dug up a service line leading to a Flint home as part of a separate effort funded by group of private, charitable, business and community groups.

Also Friday, Democratic Rep. Dan Kildee of Michigan is set to lead a delegation of 25 members of congress to hear from Flint residents.