Hairline cracks in the new concrete spillway at Oroville Dam are causing concern. State Officials say the cracks were expected and do not pose a threat. A U.C. Civil Engineering Professor however says cracking in high strength reinforced concrete structures are never expected. Radio Station KQED out of San Francisco says letters show federal regulators asked State Water officials to explain the hairline cracks. They also reportedly asked what steps might be taken to address the issue. State Officials however said the cracks were anticipated.