report from the NPR. Fish die in ice pools at Roza Dam YAKIMA, Wash. (AP) _ The federal government is investigating the Roza Dam deaths of an estimated 200 young trout and possibly some steelhead listed as threatened under the Endangered Species Act. The deaths were the result of extreme icing conditions at the Yakima River dam before Christmas, as well as the closure of the Roza Canal for repairs to the power plant, said David Murillo, field office manager for the Yakima Irrigation Project. ``We didn't anticipate killing fish,'' he said Tuesday. The water behind the dam had been drained a few days prior to Dec. 26 to a level of about a foot or a foot and a half from the bottom of the pool. Had the canal been open, the flowing water would have reduced the icing, he said. Steps are being taken to avoid a similar situation in the future, he said. The deaths could expose the U.S. Bureau of Reclamation, which operates the dam, to penalties for violating the Endangered Species Act. Steelhead in the mid-Columbia Basin, which includes the Yakima River, are listed as threatened under the act, which prohibits killing the fish or harming their habitat. They are a sea-going species that can spawn more than once. They are already extinct in some rivers, and their numbers have dwindled to the low hundreds in some areas. Recent runs in the Yakima, Walla Walla, Umatilla, John Day and Deschutes rivers combined have averaged about 13,000 fish, down from from a historical run of 100,000 in the Yakima River alone, according to the National Marine Fisheries Service. Brian Gorman, a Fisheries Service spokesman in Seattle, confirmed that the agency was investigating. However, he said, it was policy not to comment on such probes in case they didn't pan out or until enforcement action was taken. The fish, all believed to be less than a year old, died when they were trapped under 5-inch thick ice covering shallow water that remained when the pool behind the dam was drained. The dead fish were found Dec. 26. NMFS will test the fish to determine if any were steelhead. Because the fish were so young, laboratory testing is needed to distinguish steelhead from trout, including the resident rainbow. Murillo said the irrigation project is changing operations to prevent such kills in the future. For example, agitators have been ordered to keep water circulating and prevent ice buildup, he said. The dam is 11 miles north of Yakima, up the Yakima River Canyon.