Why couldn't it just be exactly what they said: catching drunk drivers? The more stops the officers make, the more drunk drivers they'll catch. And if this is a statistically significant time period, then sounds like it might be an intelligent use of resources.
Grant money pays for increased patrols, often times targeting special offenses (Over the Limit, Under Arrest / Click it or ticket / etc).
The language of the OP's article is standard as well. My lovely Commonwealth has 351 towns, so if every town is eligible for the grant, then it's common to say "Over 300 Police Departments will be out this month looking for...."