Harris County Commissioners Court on Tuesday unanimously approved the hiring of four new assistant district attorneys to prosecute environmental crimes and appointed a new interim head of the Pollution Control Services Department, the latest moves toward reform after two massive, recent chemical fires caught the county unprepared.

District Attorney Kim Ogg, who unsuccessfully lobbied court members in February to approve 102 new prosecutor hires, found a more receptive audience to her argument that the county needs to more aggressively pursue charges against polluters. The request also included two investigators and two support staff.

Assistant District Attorney Alexander Forrest, who leads the office’s environmental division, said prosecutors primarily investigate minor crimes, including mom-and-pop operations that illegally dump chemicals. With more resources, he said the county can pursue complex cases against large industrial firms.

Forrest said the five misdemeanor charges the district attorney brought against Intercontinental Terminals Co., in which the county alleges the firm polluted waterways during the petroleum storage tank fire in March, likely could have been complemented with more serious charges through a more thorough investigation.

“If taxpayers want the environmental arm of the district attorney’s office to be primarily tied up in housekeeping violations, I think it’s a disservice to the community,” Forrest said. “We have to go after the cases we know are happening that we can’t see.”

Vivian King, Ogg’s chief of staff, said prosecutors are so busy they sometimes are forced to ignore tips from would-be whisteblowers.

The three Democratic court members, who sank Ogg’s original request to increase the prosecutor corps by a third, said they were trying to strike a delicate balance between improving the county’s ability to prosecute polluters while also investing in efforts to prevent environmental crimes. They warned Ogg against coming to Commissioners Court with a series of small hiring requests.

“We need to be thoughtful, and making clear, that we’re not opening the door for the 102 new prosecutors to be brought piecemeal,” Hidalgo said. “There’s a reason why we wanted to look at an evaluation of the criminal justice system as a whole.”

Precinct 3 Commissioner Steve Radack, who supported hiring the 102 new prosecutors in February, said the court missed an opportunity to improve the district attorney’s environmental crimes division. The staffing boost court members approved Tuesday was included in Ogg’s original request.

Houston attorney Rusty Hardin, who represents Arkema executives facing criminal charges after the companies failed to prevent fires at its Crosby plant following Hurricane Harvey, said prosecuting petrochemical companies is a misguided idea. He said charging executives would fail to serve as a deterrent and instead encourage firms to share less information with the public during incidents.

“If every time one of these tragedies happens on the Ship Channel, if they think if they make a discretionary decision, they can be charged with a crime, they’re not going to come forward,” Hardin said. “I’m just tired of a tragedy turning into a felony. Sometimes, bad stuff happens.”

A number of speakers urged the court to approve the hires Tuesday.

Nicole Scalin of the Galveston Bay Foundation said settlements the county has won from environmental cases has allowed the nonprofit to conduct water testing during incidents such as the ITC fire. Sgt. Mark Kilty, an environmental crimes supervisor at the Houston Police Department, said his officers work closely with the district attorney and would benefit from more prosecutors.

Court members on Tuesday also accepted the resignation of Pollution Control Services Director Bob Allen and appointed his deputy, Latrice Babin, as interim director.

Last week, Precinct 2 Commissioner Adrian Garcia criticized how Pollution Control Services responded to the ITC fire, and said he lost faith in Allen’s leadership. The county initially had no ability to process and publish real-time air monitoring results and scrambled to design a website from scratch.

Allen announced his retirement on April 4, though he said the timing was unrelated to the fires.

Babin, an environmental toxicologist, earned her doctoral degree from Texas Southern University and joined Pollution Control Services in 1995.

Court members approved a nationwide search, at a cost not to exceed $10,000, to find a permanent director for the department.

The court at recent meetings has approved lawsuits against the two firms where the blazes occurred, Intercontinental Terminals Co. and KMCO, and the county fire marshal has launched two investigations. Court members also have asked county departments to re-evaluate their preparedness for natural and manmade disasters.

Zach Despart covers Harris County for the Chronicle. You can follow him on Twitter or email him at zach.despart@chron.com .