FILE – Water flows down the Oroville Dam’s crippled spillway in Oroville, Calif., on Feb. 28, 2017. Americans wondering whether a nearby dam could be dangerous can look up the condition and hazard ratings of tens of thousands of dams nationwide using an online database run by the federal government. But they won’t find the condition of Oroville Dam, which underwent a $1 billion makeover after its spillway failed. (AP Photo/Rich Pedroncelli, File)

(AP)   The condition ratings of thousands of dams across the U.S. remain a secret despite changes to improve the transparency of a national database. The U.S. Army Corps of Engineers used to withhold condition assessments from its National Inventory of Dams because of security concerns stemming from the Sept. 11, 2001, terror attacks. Under a recent policy change, condition assessments and hazard ratings are available for more than one quarter of the 92,000 dams in the inventory. But the Corps still allows federal agencies and states to keep some information confidential. That means conditions still aren’t being made public for some of the nation’s biggest dams.