Four people were arrested and 13 more were cited during Saturday night's DUI/driver's license checkpoint in the 400 and 500 block of East Lockeford Street in Lodi.
Lodi police screened a total of 336 vehicles.
Officers issued seven field sobriety tests and two drivers were arrested on suspicion of driving under the influence of alcohol during the 5 1/2-hour checkpoint.
Another driver was arrested on suspicion of driving under the influence, and police said he was in possession of three grams of heroin. He also had a suspended license for prior DUI convictions, police said.
Six drivers were cited for operating a vehicle without a license, and seven were cited for operating a vehicle while their license was suspended or revoked.
One driver was arrested for outstanding warrants.
Nine vehicles were towed, and eight of those were impounded.
The checkpoint lowers DUI deaths and injuries, police said. According to the National Highway Traffic Safety Administration, checkpoints have provided the most effective documented results of any of the DUI enforcement strategies, while yielding considerable cost savings of $6 for every $1 spent.
The checkpoint was funded by a grant from the California Office of Traffic Safety, through the National Highway Traffic Safety Administration.
The Lodi Police Department conducted the checkpoint from 7 p.m. Saturday until 12:30 a.m. Sunday, when officers ended the checkpoint due to the thunder and lightning that wreaked havoc in the Lodi area.