The generators were being used to power critical services such as traffic lights which, along with 70,000 homes, lost power when Cyclone Marcia hit last Friday.

Rockhampton criminal investigation branch Acting Detective Inspector Luke Peachey said police were working around the clock to find the thieves.

"This is a low act and we are determined to catch everyone responsible," he said.

"It is beyond belief that in a time when the community of Rockhampton is pulling together, helping each other out, that some people think it is okay to steal much needed and invaluable generators.

"Some of these have been stolen from intersections where the possibility of serious crashes due to traffic lights being out remains high."

Acting Inspector Peachey said mosts of the thefts happened between Tuesday and Sunday.

He said some determined offenders had even broken chains in order to steal the machines.

Police patrols have been increased in the areas were generators are operating and Acting Inspector Peachy urged members of the community to report suspicious behaviour.

"While we have a number of positive lines of investigation underway at the moment, and have suspects in our sights, I would still appeal to members of the public to contact Crime Stoppers with any information," he said.

Nearly 70,000 homes and businesses in the Rockhampton and Yeppoon areas were left without power when the storm hit last week.

Ergon spokesman Mark Timmerman said about half of those premises that originally lost power, about 35,000, were reconnected on Wednesday.

He said the energy provider aimed to have all urban areas of Rockhampton and the Capricorn Coast reconnected by the weekend.

Outlying areas are not expected to be back online until early next week.

Meanwhile questions have been raised about why the Callide Dam's automatic floodgates opened when the storm hit on Friday, sending a two-metre-high wall of water rushing through the Callide Creek and on to Biloela, Jambin and Goovigen.

The water destroyed homes and businesses, killed livestock and flattened crops.

Sunwater spokesman Tom Vanderbyl said on Wednesday opening the gates earlier in order to reduce the water levels would not necessarily have helped.

"People are asking us, why didn't we force open the automatic floodgates?" he told Fairfax Radio 4BC.

"We simply don't know if that would've made things better or worse."

"There is a real possibility that it might've made things worse."

Former Queensland Fire Service deputy commissioner Iain MacKenzie, appointed Queensland's Inspector General of Emergency Management in 2013 after seven years as the QFS deputy commissioner, is expected to lead an independent review of the incident.

-With AAP

Anyone with information about the Rockhampton generator thefts is asked to contact CrimeStoppers on 1800 333 000.