Most Animal Control Departments are government agencies. As such, they are mandated to provide services within their jurisdiction. These services may include handling and providing care for
sick or injured stay animals, dealing with animal-related complaints, surrender of stray animals, licensing, code enforcement, and quality of life issues.
Each department has different policies in terms of pick-up vs drop-off, hours, and eventual outcomes for surrendered animals (including euthanasia). Most of them also contract with established shelters
to provide the bulk of their services, but excluding those activities that require a degree of enforcement authority (complaints, code enforcement, cruelty seizures/investigations, etc.).
If your city is not listed and you live in Santa Clara County, you may not have an animal control agency. Contact your police non-emergency line for assistance.