Law enforcement’s annual end-of-summer DUI crackdown resulted in 309 arrests throughout Santa Clara County, according to authorities.The arrests, all on suspicion of driving under the influence, were reported by sheriff’s office and police departments from Aug. 16 to the end of Labor Day, Sept. 2, according to Sheriff’s Sgt. Kurtis Stenderup. Some agencies had not yet reported their total DUI arrests for the period as of Wednesday morning. In 2012 during the same time period, local law enforcement agencies reported 390 arrests on suspicion of DUI, Stenderup said. The arrests were part of the annual “Avoid the 13” DUI crackdown, in which police place extra officers and resources on the roads during holiday weekends and other expected high-traffic times. The effort includes sobriety checkpoints, saturation patrols and routine patrol by 13 law enforcement agencies throughout the County. Avoid the 13 is funded by a grant from the California Office of Traffic Safety, through the National Highway Traffic Safety Administration. Police are planning more Avoid the 13 anti-DUI efforts during the upcoming Halloween and Thanksgiving holidays, Stenderup said.