An independent review says Townsville was spared more widespread flooding six months ago by a decision to operate spillway gates at the Ross River Dam manually on four occasions – a deviation from the standard operating procedures.

“Significantly more” flooding would have occurred if there was no Ross River Dam, Queensland’s Inspector General Emergency Management says in a new report assessing the effectiveness of preparatory activity, and response to, monsoon flooding in north Queensland in January and February.

“Arguably, there would have been increased flooding if the standard operating procedures were followed and there was no manual gate operation of the Ross River Dam,” the 188-page report says.

From January 24 to February 9, torrential rainfall across north Queensland caused widespread flooding. Some locations, including Townsville, exceeded average annual rainfall during the event, recording more than 2000mm.

Since the monsoon event, questions have been raised about the extent to which releases from the Ross River Dam impacted downstream communities. A community survey found 30% of residents believed floodwaters would not have been so high had the water been released earlier.

But the Inspector-General's report says an independent assessment by engineering consultants BMT Eastern found the impacts would not have differed appreciably from the actual event had an increased volume of water been released earlier.

Insurance claims after the event stand at $1.24 billion. The Insurance Council of Australia estimates, that of the 29,852 claims lodged, just under half of property claims are closed, 61% of contents claims are closed and 80% of motor claims are closed.

Townsville Mayor Jenny Hill says many people are still not back in their homes and are experiencing problems with insurance claims, “and that’s why we must keep up the pressure for the insurance industry to do the right thing”.

She says she is committed to better community education after affected residents revealed they did not understand terms used to communicate flood risk probability.

Around 8000 Townsville residences were impacted by the floods, and 2490 people were accommodated at five evacuation centres.