Since the tallest dam in the United States threatened California with catastrophe last winter, state officials have responded with policies to stanch the flow not just of water but of information.

The latest example is the Legislature’s vote to exempt a whole class of crucial information about dams from the state’s public-records law. A provision in the recesses of a lengthy budget-related bill requested by the governor and passed by both houses last week could prevent public and press access to plans for responding to dam emergencies.

That is hardly an academic issue in the wake of February’s brush with disaster at the Oroville Dam, where record rains and brittle spillways forced nearly 200,000 to evacuate downstream areas. Gov. Jerry Brown’s administration has since awarded a $275 million contract to repair the structure and, last week, ordered new inspections of some 70 aging dams. At the same time, citing security concerns, the state has limited access to contract, inspection and other records despite the objections of journalists, legislators and local governments.

The bill passed Thursday, now awaiting Brown’s signature, is one of several trailer bills dealing with an array of policy issues. Among them, it expands the emergency action plans required of federally regulated dams to other dams and makes them consistent with other state emergency plans, such as those for earthquakes and tsunamis, said Kelly Huston, a deputy director of the state Office of Emergency Services. It also exempts those emergency plans, as the Sacramento Bee reported, from disclosure under the California Public Records Act.

Noting that evacuation routes and most of the other information in the plans are meant for public consumption, Huston said the administration’s intent is to make them largely public but to withhold select sensitive information, such as specific dam vulnerabilities or law enforcement officers’ phone numbers. Oroville project communications manager Erin Mellon said officials’ intent is to improve safety with more emergency planning and make most of the plans transparent. The governor’s office also noted that the draft language of the legislation was published three months ago.

But the provision nevertheless underwent little public discussion and has the effect of creating a new exception to a public-records law that already has plenty, said David Snyder of the First Amendment Coalition. The legislation’s blanket language forces the public to rely on the best intentions of state officials rather than the legal presumption that the emergency plans, like most other government records, are public.

The dam legislation certainly has important public-safety goals. And it’s possible that in an attempt to keep a narrow swath of sensitive information confidential, lawmakers and the administration have inadvertently come to the brink of creating an excessively broad and unnecessary exemption to the Public Records Act. In any case, the governor can easily reassure the public of his commitment to transparency by refraining from signing that provision into law.