Diamond Bar

Diamond Bar is the municipal law-enforcement agency for the City of Walnut in Los Angeles County, California, based at 21695 Valley Boulevard. The department serves residents, businesses, and visitors within Walnut limits in Los Angeles County. Its area of responsibility covers patrol and response to calls for service, traffic enforcement, criminal investigations inside the city, and community policing programs that support local neighborhoods and commercial corridors. Walnut sits in a California corridor that mixes residential neighborhoods with local commerce, and the police department is the primary local law-enforcement presence for day-to-day public safety inside the city. Public safety emergencies in Walnut should be reported by dialing 911.

According to the U.S. Census Bureau (ACS 2023), Walnut city, CA has an estimated population of 27,857.