By Dan Whitcomb

Jan 31 (Reuters) - More than 1,700 residents of Flint, Michigan who say the Environmental Protection Agency mismanaged the water crisis that exposed thousands of children to lead poisoning have sued the U.S. government, seeking class action status for their claims.

The lawsuit, filed in U.S. District Court in Michigan on Monday, asserted that the EPA failed to warn them of the dangers of the toxic water or take steps to ensure that state and local authorities were addressing the crisis. The plaintiffs seek $722 million in damages.

"This case involves a major failure on all levels of government to protect the health and safety of the public," the 30-page lawsuit claims. "Local, state and federal agencies and employees, working individually and at times in concert with each other, mismanaged this environmental catastrophe."

A spokeswoman for the EPA could not immediately be reached for comment on the court action.

State officials said last week that lead levels in Flint's drinking water had fallen below federal limits although they cautioned residents to keep using filtered water as the city's old lead pipes are replaced.

The water crisis erupted when tests in 2015 found high amounts of lead in blood samples taken from children in Flint, a predominantly black city of about 100,000.

Flint was under the control of a state-appointed emergency manager when it switched its water source to the Flint River from Lake Huron in April 2014. The more corrosive river water caused lead to leach from pipes and into the drinking water.

Lead poisoning stunts children's cognitive development, and no level of exposure is considered safe. Flint's contamination prompted dozens of lawsuits and criminal charges against former government officials.

The city switched back to the previous water system in October 2015.

In December, Michigan Attorney General Bill Schuette charged four former officials with conspiring to violate safety rules, bringing to 13 the number of current and former officials charged in connection with the crisis.