Here's the history, taken from John Gorman's article on Portland fountains.
"Early Portland legend and lumber baron Simon Benson— nondrinker himself—realized that local saloons were slaking the thirsts of his parched timber-company employees. Eager to provide an alternative refreshment, he originally paid for the installation of 20 fountains created by noted Benson Hotel designer A.E. Doyle, which he insisted flow 24 hours a day uninterrupted.
Soon thereafter, Benson proudly noted that saloon sales dropped nearly 40%—a trend more likely attributed to the growing temperance movement than to free water fountains. Still, the Bubblers have remained famous, functional Portland landmarks, and on hot summer afternoons they are especially appreciated by all."