FLINT, MI -- The city's congressional delegation wants to know when the U.S. Environmental Protection Agency's inspector general plans to complete a Flint water crisis investigation that started more than two years ago and when it will be released to the public.

U.S. Sens. Debbie Stabenow and Gary Peters and U.S. Rep. Dan Kildee, D-Flint Twp., made the request for information in a letter Tuesday, March 6, to Inspector General Arthur Elkins.

The Office of Inspector General for EPA said in January 2016 that it would begin an investigation into the causes of the water crisis and the agency's role in allowing it to unfold, but a full report has not been released to date.

In October 2016, the OIG issued a finding that criticized EPA's Region 5 office, saying it had the authority and sufficient information to issue an emergency order about the public health crisis in Flint seven months earlier than it did.

OIG is an independent office within EPA that performs audits, program evaluations and investigations of the agency.

MLive-The Flint Journal could not immediately reach a representative of the auditor general for comment on the letter from Kildee, Peters and Stabenow on Tuesday.

In addition to city, Genesee County and state government offices, EPA has been criticized for its role in allowing the water crisis to linger as long as it did after the city's water source was changed to the Flint River in April 2014.

Almost immediately after the switch, problems with city water began to show, including bacteria, elevated levels of lead and chlorine byproduct and a surge in cases of Legionnaires' disease.

Former EPA Region 5 Director Susan Hedman resigned in early 2016 as outrage mounted over her handling of the water emergency, and former EPA Administrator Gina McCarthy was criticized by a Congressional oversight committee that investigated the situation.