Revving engines and bucking bulls offer year-round thrills at the Perris fairgrounds when it’s not Southern California Fair season. But the owners of Perris Auto Speedway, Toro Wapo Arena Event Center and the Family A Fair Inc. concessions company fear what will happen to the car races, rodeos and live music — and the people whose jobs depend on them — when construction starts on a multi-year project at the Perris Dam. They’ve sued the California Department of Water Resources, which is overseeing the Perris Dam Modernization Project. … In 2005, Water Resources determined the dam was especially vulnerable to major damage from an earthquake. Since then, a three-phase retrofit project has strengthened the dam’s foundation and bolstered its infrastructure.