Riverside -

A countywide crackdown on drunken and drug-impaired motorists netted 129 arrests in the first three days of the operation, authorities said Monday.

The end-of-summer Riverside County Avoid the 30 campaign -- named for the number of police agencies involved -- got underway Friday morning. Between then and Sunday night, saturation patrols and sobriety checkpoints were deployed in a number of locations.

The 129 motorists arrested on suspicion of DUI since Friday compare to 176 arrested during the same phase of last summer's Avoid campaign, according to Riverside police Sgt. Robert Tipre, the Avoid coordinator.

A dozen people were injured in possible alcohol-related collisions over the weekend. This time last year, two people were killed and 12 were seriously injured in similar wrecks, according to Tipre.

The Avoid crackdown, which continues through Labor Day weekend, is part of a national campaign, ``Drive Sober or Get Pulled Over.''

This week, anti-DUI operations are planned in Banning, Beaumont, Desert Hot Springs and Moreno Valley.

The Avoid campaign will coincide with the California Highway Patrol's ``Maximum Enforcement Period,'' set for Aug. 29-Sept. 1. During the MEP, all available CHP officers hit the streets to nab intoxicated motorists, speeders and other traffic violators.

During last summer's two-week Avoid campaign, 695 people were arrested on suspicion of DUI, compared to 710 in 2012.