The Breyman Fountain, donated by Mr. and Mrs. Werner Breyman in 1904, is located at the far west end of Willson Park, west of the Capitol. It was used as a watering trough for horses. There originally was a decorative statue and street lamps on the top. According to the Salem Public Library, the statue has been gone for many decades, but the fountain is believed to be a memorial to the Spanish-American War.
You can see a photo at the above link of the original fountain with the statue, taken in 1905 and with the old Capitol which burned in 1935 in the background.
The fountain is now used as a planter, no longer as a water trough.