SACRAMENTO, Calif. — Independent experts looking for the causes of the spillway failures at California’s Oroville Dam identify dozens of possible factors in a preliminary report released Wednesday.

Experts say they will look at a range of possible flaws in the concrete and foundation of the half-century-old main spillway, including whether cracks in the spillway allowed water to tear away at the concrete spillway.

Both spillways at Oroville Dam, the nation’s tallest, gave way in February, forcing evacuation orders for nearly 200,000 people downstream.

The independent experts’ final findings on the causes of the crisis at Oroville Dam are expected to be released next fall. Authorities say the preliminary findings will guide them as they repair the battered spillways.

It’s likely a combination of problems, rather than one single one, caused the damage, the preliminary report noted.

Four state senators from Northern California said Wednesday they want $100 million in the state budget for critical levee repairs after the heavy rains that damaged Oroville Dam. The levees must be repaired this year, the bipartisan group of senators wrote in a letter, adding that the investment would “save lives, protect property, and save the state billions in avoided emergency repairs.”