The City of Westlake Village is a master-planned community that is transected diagonally by the Los Angeles/Ventura County line.
The Ventura County side is comprised of 8,544 acres and was annexed into the City of Thousand Oaks in 1968 and 1972. The Los Angeles County side is 3,456 acres and was incorporated as the City of Westlake Village in 1981.
Ah yes, the challenge of distinguishing between the Los Angeles and Ventura County sections of Westlake Village. It truly is a diagonal boundary that stretches from just northeast of Lindero Canyon Road, south of Blackbird Avenue on the north to South Westlake Blvd at Kirsten Lee Drive on the south.
It is impossible to drive, bike or walk the boundary line because it crosses right through the middle of Westlake Lake. Although, you could drive along the border on La Venta Drive southwest from Watergate Road.
Further north, the border cuts diagonally across Westlake Golf Course. In fact, the driving range section of the golf course bordered on the west by Lakeview Canyon Road and on the north by the 101 is located within the City of Thousand Oaks while the rest of the course is in Westlake Village.
Costco Westlake Village and the Four Seasons Westlake Village are solely part of the City of Westlake Village, as is the Las Virgenes Reservoir.
Does it really matter what side you're on? For most, no. But there's one clear financial difference. Sales taxes. As of April 2018, sales taxes in the Thousand Oaks portion of Westlake Village are 7.25%, whereas they are 9.5% in the Los Angeles County based City of Westlake Village.