Willowbrook (also Willow Brook) Dairy or Creamery was an Oakland dairy beginning in 1907 as the Altman Dairy, run by brothers David Joseph Altman and Sam M. Altman.
It's unknown when they switched from the Altman name, but it appears as late as 1918, 4 and Willowbrook as early as 1923. 2 In 1931, they opened a new, modern plant at 2521 San Pablo Ave. It's also unknown when they stopped business or sold, but they're mentioned in an article about a lawsuit against two dairies in 1937. 3 They don't appear in the 1941 directory, and the 1944 streets directory lists Kramm Distributing at the address.
The building still stands, and a metal crest with 'WC' (Willowbrook Creamery) is visible above the door.