Environmentalists are asking Maryland officials to prosecute more polluters after learning that the number of cases the state is referring for criminal investigation has dropped by one-third over three years.

Representatives from 11 groups, including the Chesapeake Bay Foundation, Blue Water Baltimore and the Maryland League of Conservation Voters, sent a letter to Maryland Department of the Environment Secretary Ben Grumbles, urging him “to consider whether existing enforcement policies and resources are sufficient to protect our citizens.”

In the year from March 2015 through February 2016, state environmental regulators referred 222 cases to the Maryland attorney general for prosecution, according to data the Center for Progressive Reform said it obtained in a public information request. From March 2014 through February 2015, they had referred 272 cases, and in the year before that, 339 cases.

The letter said that air pollution referrals decreased about 50 percent, lead poisoning prevention referrals declined 46 percent, and clean water referrals dropped 27 percent.

The groups accused state environmental policing to be “quiescent” relative to national enforcement of clean air and water laws.

“To fully meet the state’s commitment to its neighbors with regard to the Chesapeake Bay, as well as its commitments to the citizens of Maryland to ensure that our air, water, and lands are clean and healthy, we need a full commitment to enforcing the law,” the letter said.

A state spokesman said officials are reviewing the letter.

“The Department of the Environment is fully committed to enforcing the laws and regulations that protect public health and the environment,” spokesman Jay Apperson said in an email.

Most of the department’s enforcement activity involves “working with permit holders to correct any minor deficiencies,” he said. “This assistance may be the most efficient method to achieve compliance.”

Significant or repeated violations can warrant penalties, corrective orders, legal injunctions and criminal sanctions, he added.

Gov. Larry Hogan (R) has emphasized a business-friendly, customer-service-oriented approach to environmental regulation in the past.

But the issue is not a political one, the groups said. “To be sure, enforcement trends were headed in the wrong direction in the final years of Governor [Martin] O’Malley’s administration,” they wrote. The numbers they cited cover the final 23 months of the O’Malley administration and the first 13 months of the Hogan administration.

The letter calls on Grumbles to restore more than a decade of funding cuts that have reduced the state’s staff of inspectors, increase financial penalties for repeat-offender polluters, and more consistently levy fines on polluters. The groups call for the state to establish a task force “to discuss methods for identifying and bringing to justice chronic violations of the law.”

Attorney General Brian E. Frosh (D) said that although he can’t control which cases are handed up to his office, he “would like to see more law enforcement.” Efforts to work with polluters without taking action to enforce the law isn’t fair to businesses that spend significant sums to comply with environmental standards.

“We don’t want to create an economic benefit to folks who are polluting,” Frosh said. “If we get the cases, we’re going to enforce the law. We’ll do it vigorously.”

Other groups that signed the letter include the Chesapeake Legal Alliance, the West and Rhode Riverkeeper, the Environmental Action Center, Food and Water Watch, the Potomac Riverkeeper Network, the Assateague Coastal Trust and the Environmental Integrity Project.

State environmental regulators levied $3.7 million in fines and took about 7,700 enforcement actions in fiscal 2015, according to an annual enforcement report. The state reported $3.6 million in fines and 2,150 enforcement actions in fiscal 2014. The massive increase in enforcement actions came from a surge of about 5,000 actions regarding lead exposure in fiscal 2015.

— Baltimore Sun