According to Wikipedia: "Santa Anita Park is a thoroughbred racetrack in Arcadia, California, United States. It offers some of the prominent racing events in the United States during the winter and in spring. With its backdrop of the San Gabriel Mountains, it is considered by many as the world's most beautiful race track. The track is home to numerous prestigious races including both the Santa Anita Derby and the Santa Anita Handicap as well as hosting the Breeders' Cup in 1986, 1993, 2003, 2008, 2009, and since 2012. In 2010, Santa Anita's ownership was moved to MI Developments Inc. (MID). Trevor Denman is the track announcer."
These photos were submitted by JO, who notes that these "old style troughs [are located at the Los Angeles Turf Club]"