The county's anti-drunken driving task force, led by Petaluma police, was out in force for 18 days around Labor Day, arresting 171 drivers on suspicion of DUI.
The campaign, which began Aug. 16 and was meant to deter drunken driving over Labor Day, ended Monday.
The number of arrests was up slightly from years previous, and the number of collisions relating to drunken driving was down to a five-year low. There were three collisions this year, versus 10 last year.
"A 70 percent reduction is a welcome statistic for sure," said Petaluma Sgt. Ken Savano.
One of the three crashes resulted in a fatality this year.
In addition to holding checkpoints, police conducted a county-wide DUI warrant sweep that found 23 DUI offenders with DUI warrants. Court stings targeting drunken drivers were conducted as well.