The provincial ombudsman says the government department failed in its duty to help the applicant by not responding openly, completely and quickly.
The request was for information about flood control measures in the area northwest of Winnipeg since 1960.
More than 700 people from the Lake St. Martin community were forced from their homes last spring by floodwaters.
The area was so damaged most of the homes are no longer inhabitable.
The department says it accepts the Ombudsman's report, including a recommendation that it should apologize, and is working to provide the requested information.