Besides the financial penalties by parking in front of a fire hydrant, you are delaying the firefighters from getting water into a burning building. In Oregon City, the fine can be hundreds of dollars.
The Ordinance:
811.550 (16) Within 10 feet of a fire hydrant. Exemptions under ORS 811.560 (Exemptions from prohibitions on stopping, standing and parking) (2) and (4) to (7) are applicable to this subsection.
811.560 (2) When applicable, this subsection exempts vehicles stopped, standing or parked momentarily to pick up or discharge a passenger.
(4) When applicable, this subsection exempts vehicles owned or operated by the state, a county or city when stopping, standing or parking is necessary to perform maintenance or repair work on the roadway.
(7) When applicable, this subsection exempts the driver of a vehicle that is disabled in such manner and to such extent that the driver cannot avoid stopping or temporarily leaving the disabled vehicle in a prohibited position.