The City of Lake Oswego has an interactive map available to search for information. One of these is a hydrant map that will show the hydrants (Marked in red) and the water lines with sizes.
Click HERE for interactive map.
Fire flow test data provides necessary information for water service planners, fire protection bureaus, and building designers. Here you can find flow information on tested hydrants. Flow information on Hydrants tested with GPM at 20 PSI.