State scientists wearing gas masks, hard hats and hazmat suits gathered in Sacramento last weekend, looking like they had been assigned to a toxic cleanup.

But instead of a chemical spill or a noxious gas release, the scientists were geared up for what they say is another disaster: Their pay.

“Enough is enough,” said Paul Modrell, a scientist who works for the San Francisco Bay Water Board.

The two-day rally at the Department of Human Resources headquarters in Sacramento coincided with a new round of contract negotiations between their union, California Association of Professional Scientists, and Gov. Jerry Brown. It was a rare public display of anger by a professional class of state employees. Generally speaking, scientists, engineers and attorneys don’t take to the streets with their grievances.

In fact, the 3,000-member scientists union didn’t sanction the action. The 100 or so scientists who rallied said they raised about $1,000 to print up cards, signs and T-shirts and organized the event on their own time.

Given the union’s small size and relatively few members working in Sacramento, the organizers said they were encouraged by the turnout. (By comparison, a similar percentage turnout of SEIU Local 1000 members would be about 3,200 employees.) A union-funded rally may have generated more interest – and more protesters.

Union Vice President Patty Velez said Monday that CAPS officials were with the marchers “in spirit” and said the rally was “helpful” to negotiations.

“It’s great to see them doing this on their own,” Velez said.

There’s no denying, however, that the rally demonstrated frustration with Brown and with the union. Scientists’ pay averaged $63,373, according to payroll data. No one on either side of the bargaining table disagrees that state scientists earn one-third less than counterparts in local governments. The Brown administration’s own salary-comparison surveys bear that out.

In some instances, state engineers doing the same work earn more. And, the union and its members say, the pay inequity threatens everything from food safety to water quality.

For years, CAPS has sought pay hikes to close the gap. Last summer, after the rank and file rejected a contract with a modest raise, union negotiators endorsed another deal with less money but a much shorter term.

Union leaders promised that taking the agreement would quickly restart talks and lead to substantial pay increases once Brown got past the politics of the 2014 election.

It hasn’t happened so far. And if a deal isn’t done and put to a legislative vote before Sept. 11, lawmakers will go home and the scientists face the prospect of a long winter with no raise.

“I’m not sure our union knows how to negotiate, to be honest,” Modrell said.

Then, perspiring slightly under the midday sun in his hard hat and reflective vest, Modrell joined his colleagues.