Long counted among America's deadliest cities for its homicide rate, Flint, Mich., is now grappling with another life-threatening concern: its lead-contaminated water supply.

The issue has grown over the months from a local fiasco to take on national prominence as a public-health crisis. U.S. President Barack Obama declared a state of emergency last week, a move that will release $5 million in federal funding for equipment and resources to help the 95,000 residents affected by the contaminated water.

Last night, Michigan Gov. Rick Snyder addressed the ongoing crisis. But how it all began, and the political fallout, goes back to a cost-cutting measure that went into effect in April 2014.

How did it start?

Flint Water

Pastor David Bullock holds up a bottle of Flint water as Michigan State Police hold a barrier to keep protesters away from Michigan Gov. Rick Snyder's office. (Jake May/Flint Journal-MLive.com/Associated Press )

In a bid to save about $5 million over two years, the struggling industrial town of Flint cut its ties with the Detroit Water and Sewerage system and instead hooked up its municipal water system to the Flint River in April 2014. The switch was meant to be temporary until the supply could transition to a new regional water authority, the Karegnondi system.

For nearly 50 years prior, Flint had pumped in water from Lake Huron, which was treated through the Detroit system.

What were the effects of the contamination?

Water Protest

Gladyes Williamson holds up a discoloured jug of water and chants along with other protesters outside a farmers' market in Flint, Mich. (Sam Owens/Flint Journal-MLive.com/Associated Press )

Residents quickly began complaining about the cloudiness, colour, taste and smell of their new tap water. Some also noted rashes, hair loss, headaches and other problems, blaming the drinking and bathing water for the adverse health effects.

Within four months of the changeover, tests of local samples detected fecal coliform bacteria as well as alarming levels of the potentially harmful chemical compound trihalomethanes (THMs), a byproduct of chlorine.

Last summer, three boil-water advisories were issued in the span of 22 days.

Some have also attributed a recent outbreak of legionnaires' disease to the water crisis. A total of 87 cases of legionnaires' have been found in and around the Flint area since June 2014, 10 of which resulted in death. But officials have cautioned there's no clear evidence of a link.

Why was the water so bad?

Flint Water

In this April 2014 file photo, water from the Flint River rushes into the Flint water treatment plant. General Motors announced in October 2014 that engine crankshafts showed rust after they were machined with Flint River water. (Samuel Wilson/Flint Journal/Associated Press)

Water sourced from the Flint River is more corrosive than the Lake Huron supply. Left untreated, the Flint water pumped through municipal system was eating away at the pipes, resulting in lead that eventually leached into the tap water.

Cognitive problems associated with lead exposure can be especially pronounced in young people. Doctors say poisoning from lead, an irreversible neurotoxin, can cause learning disabilities in young children, as well as speech and behavioural problems. In adults, exposure to toxic levels of lead can harm the kidneys.

General Motors also announced in October it would stop using Flint water, blaming it for rusting mechanical parts at its local engine plant.

Who sounded the alarm?

Flint Water

Dr. Mona Hanna-Attisha, director of pediatric residency at Hurley Children's Hospital, speaks during a news conference about water quality in Flint, Mich. (Jake May/Flint Journal-MLive.com/Associated Press)

Residents say they were kept in the dark for 18 months, assured their water was safe, until a local physician started noticing signs of lead poisoning in some of her patients.

Dr. Mona Hanna-Attisha, a pediatrician at the city-funded Hurley Children's Hospital, is credited as being the doctor who first brought the problem to the state's attention.

Hanna-Attisha ran tests and noticed elevated blood-lead levels in Flint children in August. She brought her data to state health officials and later released her results to the public in September. At the time, the state dismissed her results and questioned her research, saying the government's own tests did not show the same blood-lead level increases.

A month later, officials validated her data, acknowledging there was a problem.

What was the political fallout?

MLK Day Michigan

Michigan Gov. Rick Snyder speaks at the University of Michigan's Flint campus. Snyder apologized in December for the state's handling of the Flint water crisis, which he has termed a 'disaster.' (John M. Galloway/Detroit News/Associated Press)

Snyder apologized for the state's handling of what he has termed a "disaster" in late December, and accepted the resignation of Dan Wyant, the director of Michigan's department of environmental quality. Critics, including Democratic presidential candidate Bernie Sanders, have called for Snyder to step down, saying months of inaction have broken trust in the governor.

Last week, Michigan's attorney general opened an investigation into whether any laws were broken.

Obama also declared a state of emergency in response to the water problem, authorizing the Federal Emergency Management Agency to kick in $5 million in aid. The water crisis did not qualify for much more federal funding as a "major disaster" because the crisis was man-made.

Lawyers have filed three class-action suits so far on behalf of Flint residents, alleging that state officials made multiple false assurances to claim the water was safe.

What's being done to fix this?

MICHIGAN-WATER/

Anthony Fordham picks up bottled water from the Food Bank of Eastern Michigan to deliver to a Flint school. Flint reconnected to the Detroit water system in October at a cost of $12 million. (Rebecca Cook/Reuters)

Flint reconnected to the Detroit water system in October at a cost of $12 million, and Snyder declared a state of emergency on Jan. 5.

The Michigan National Guard was called in to distribute boxes of bottled water as well as filters and lead-testing kits, joining volunteers and police in a door-knocking campaign.

The Hurley Children's Hospital is working with Michigan State University on a project to monitor blood-lead levels in Flint children.

Meanwhile, frustrated Flint residents continue to drink and wash themselves with the bottled water, fearing long-term consequences of the lead-water exposure.